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I’m in the incredibly fortunate position to be offered some very generous donations. Part of being a big deal Youtuber with over ten thousand subscribers maybe?
I don’t know how to put this, but. I’m kind of a big deal.
One of these incredible donations came from the lovely Andrew Searle, who contacted me to offer an Amiga 1200 for this years charity fundraising project. (much more on this machine in an upcoming episode! Its going to be very interesting!
Andrew popped over from somewhere on the other side of the country and delivered, in person, a veritable pile of cool stuff.
This mini amiga for instance. Will be in the auctions too! (October 19th, put it in your diary. 12 hour live stream, special guests, charity fundraising to help buy miniature donkeys! Details about the charity event at the end of this video))
As well as the Amiga 1200 Andrew handed over a working Amiga 600.
He also gave me this! Now this was actually for me.
Well as much as I like getting free stuff I already have an Amiga 600 and it would be very greedy of me to accept another one. So this one is going into the charity auctions to raise money to help buy those tiny donkeys for the Befriending Scheme.
As you can see here, it’s quite yellowed. I’ll try to do something about that.
Inside is a fully equipped Amiga 600, with compact flash hard drive storage, a 4mb fast ram expansion sitting on the 68000 CPU, and a 1mb chip ram expansion in the trap door with a battery for presumably the real time clock.
It’s a cracking machine and worthy of a good home. But it also seems to work just fine, so why are we here today?
Well how about a little bit of restoration?
This A600 was donated by Colcuz Colin. The insides were restored by the brilliant Retro Passion, who, by the way, offer a great service if you don’t want to do it yourself, and quality parts if you do fancy having a crack at retro repairs. You can find a link to their website in the description. No affiliation! I just like them.
The outside of this Amiga was restored by Colcuz himself. I believe he used peroxide creme, something I have dabbled with in the past with a Super Nintendo case, but it’s not something I trust completely, having seen mixed results on other youtube channels.
If you compare these cases you can see Colcuz managed to get the case right back to the original off white colour. This other one though is decidedly yellowed. With all the keys being a quite uniform colour.
So what’s the plan here?
Well first of all I’ll strip this keyboard down and give everything a good clean. Then I think I’ll use the submersion method with keys to bring those back to a better shade, and the case I’m going to try just plonking it out in the sun for a couple of days and see what happens. It’s low risk and I think the end result I am going for with this one is just to look a bit better. It doesn’t matter too much to me if it’s still a bit off colour at the end, I’m just looking for improvement here, a bit of patina can also be a good thing.
Keen followers of my content will remember I used the submersion method on the keys from the purple and gold Amiga 500, and had problems with the keys floating. In the comments of that video I was advised by a viewer to put the keys into a plastic bag and get rid of all the air, that would mean they were all immersed and there would be no marking from the puddles on the keys.
Let’s see how that pans out shall we?
After a thorough wash and rinse
I’m ready to pour the peroxide into the bag…
Gloves are essential for this.
And a steady hand!
The plastic tub has hot water inside which I hope will help speed up the process, it’s not too hot but cold water would slow things down. All the air is now out of the bag and its double sealed.
And off it goes out into the bright sunshine, right next to the sunbathing top case.
I left the keys out there for about 6 hours, occasionally giving them a stir. And good thing too! Hydrogen peroxide is an unstable liquid, when heated it breaks down into water and oxygen. The first time I gave the bag a check I found it had blown up like a balloon! This kinda made the bag a bit of a waste of time, but I persevered and deflated the bag each time it inflated throughout the 6 hours. In the end the keys do look marvellous. Probably the best results I’ve had with retrobriting so far.
As you can see, two days in the sun has certainly taken the yellow tone down quite a few levels. It still isn’t even close to the original colour, like the other Colcuz one. But I think it’s good enough for me. If the person that wins it wants to go that extra mile they can do that too!
I will give this a treatment of 303 UV protectant (thank you Life Size Teddy Bear) which will hopefully slow down the inevitable re-yellowing.
The hard drive in here is chock full of software. I’m quite tempted to image this for my own 600. And as you can see it seems to work well.
It does take quite a long time to boot, but that might be the way the hard drive has been set up. I honestly don’t know what exactly has been installed on here at this point. But just in case there is a problem I gave the insides an inspection to make sure everything is as it should be. And at first glance I couldn’t see too much wrong.
With the naked eye there were only a few points around the caps that showed signs of leakage. Nothing was gloopy or burnt so that was a good sign. And then I looked a little closer.
Ah yes, these caps need to be changed.
Now, I must admit, at this stage I switched off the cameras, heated up the soldering iron and just got on with it. I’ve recently recapped an Amiga 600 on camera so I didn’t think it would be a good idea to do it again. It’s just a recap. What could go wrong?
Yeah, that’s what went wrong. Well one of the things.
It seems the caps were hiding a lot of problems. My usual method for removing caps is to use two soldering irons and just lift them off that way. It’s not the easiest thing to do in certain positions on an A600. These ones next to the modulator, or these 2 near the coil are very difficult to get to one side. In the past I have resorted to snipping the ones next to the coil. It’s a little lazy as removing the coil is not beyond my toolset and abilities, but so far I’ve not had an issue removing caps this way. Well. Until now. One of the pads just lifted right off the board. Oh dear I thought to myself! That’s a problem!
OK, let’s not panic. How about going back to the 2 iron method. That’s not going to let me down. Is it?
Now it’s worth mentioning that everyone has an opinion on what the best method is for removing SMD electrolytic capacitors. And everyone is right. Kinda. If you find a way that works for you that’s great. I have even tried twisting caps off, just to see what happened, and it was totally fine. But, for me, I like to use two soldering irons because in most instances I feel it’s the safest way to get the job done without too much risk. And that’s the key here. Whichever way you do this there is risk. Mechanically twisting, no matter how much you push down, is putting force across the pads in a direction where they have little strength. Healthy pads that are well attached to a board will usually be fine with this, especially if the legs have had a nice bath in electrolyte for a few decades to weaken them.
Hot air is great. Many swear by it. But you have the downside of heating not just the component pads you want to melt. And heat is heat. If those pads are damaged they have a good chance of taking the pads off this way too.
Two irons, or tweezers, to me sound like the best compromise. But they’re not perfect. You’re putting a lot of heat into a small area with double the power. It’s easy to slip and damage something else, and hard to judge if one side is melted sometimes. And it’s very easy to rush and push the cap with a bit too much force.
And this is what happened on one of the following caps. Both of these pads just lifted up with the cap. There was little I could do. The damage had already been done.
I then set about experimenting with different methods on the rest of them. Some of the caps were almost falling off the board and I managed to get these two here off just by wiggling them a bit to weaken the legs. And the horror underneath really showed what the problem was. On this side of the board the corrosion was not too bad, it hasn’t affected the pads or surrounding traces and components. I cleaned it up and installed some new caps. Not a problem.
The next area was the reset circuit. This is often an area of concern, so I took the time to remove the ceramic capacitors on either side of the electrolytic, just to be safe. In the event there wasn’t much goo under those components. But it was definitely a good idea to clean under there.
At this point I took a look at the caps adjacent to the audio jacks, which I’d already removed along with the keyboard connector for ease of access. And here, after a clean up, I spotted a problem. I decided I needed to record this and switched on my microscope to take a closer look. Right underneath C334 is a trace that has a complete break. I spent a few minutes with some magnet wire, flux and patience, and this is now a complete circuit again.
I’ve not yet had an excuse to use my new uv curable solder mask and UV light up till now. Again thank you to my super supporter Life Size Teddy Bear who bought these.
With that protected I can get these caps back on the board and then it’s time to try pad replacement. Another new skill to learn!
This area is under the caps right next to the modulator. The solder mask on these traces looks weird. What concerns me here is that the electrolytic cap juice could have worked its way under the solder mask and might be eating into the traces. I’m not sure why else it would only be flaking off on the traces and not on the surrounding areas of the solder mask that doesn’t cover copper? To be safe I am scraping all of it away. I don’t want this to be going bad a year down the line.
The trace running under this large resistor is a worry. It has corroded above and below here, and there’s plenty of corrosion on the solder too. This was in the area where the two pads lifted where the corrosion is worst. I wonder what’s underneath this resistor then? Could it have shielded the trace below? It checks out with continuity, so it’s not broken.
Oh. Well then. That answers that question! Glad I took this off now! Just cleaning the gunk away with IPA and a cotton bud reveals the trace has lost its solder mask. It still seems to be intact, so I just got here in time. I’m running a piece of braid with a small amount of solder on it to give the trace a little more mass. And then covering it up with a thick coat of solder mask. Along with all the other exposed copper. My UV lamp isn’t big enough to cure all of this area at once, so I take advantage of all the free UV outside during the day. Whilst the board is sunbathing the resistor I removed gets a bath and a scrub. And then it’s replaced. The solder doesn’t look very pretty but I tested it and it’s well attached.
I’ve been putting it off, but now it’s time to tackle the missing pads. Another thing I’m still learning about.
I’ve seen other youtubers use all kinds of methods for this job, from pieces of solder braid to bits of wire. My first instinct was to try attaching the cap directly to this nearby via and the leg of the chip below. Which would have worked just fine, but the cap to the right then doesn’t fit. So that idea was scrapped.
My next idea was to use copper tape. This is slug tape and useful for all kinds of repairs, also for discouraging slugs from eating your potted plants. The adhesive on this is not heat resistant, I know it’s possible to buy some that is, and I will try to source some of that, but for now I’m hoping this will do. I just need to get the pads in the right place
Add some flux
Drop the cap in place and solder it to the pads.
Of course it’s not actually attached to anything so now it’s in place and reasonably solid, I can add bodge wires and get it connected that way. That looks good on that side, I’m happy with that. For the other side I need to remove some of the UV solder mask I applied. It’s much harder than I expected!
And I just spotted I’d missed soldering this side of the neighbouring cap. Oops!
Shaping the bodge wire is a strangely satisfying process.
Ok, that’s all attached, how does it feel? Is it stable?
Well that seems good to me. What do you think? I might, once everything is finished and working, add a dab of hot glue to stop it moving about.
This other missing pad is a bit more straightforward. I could just solder to the top side to this scraped off area, but that would look terrible with the cap at an angle. So I’m going with another copper tape replacement pad. This time a bit wider so it reaches the connection on the right side.
Flux
And some solder.
Ah, well it really didn’t stick as well this time. But as long as I can get it flat, attached and stable I think this will still be the way to go.
I’m attaching the bottom side to hold it in place. Yup, I think that’s a decent fix. A little ugly up close but I can live with it. And it looks even better with the caps in the right alignment.
Now I just need to replace all of the other caps. Starting with these ones under the modulator.
For these I’ve switched my soldering iron tip to the witches nose one. It’s a bit better at this kind of work and easier to get into these tight spaces.
And all that’s left now are the through hole caps.
All of these were removed without damage. On the ones with heavy ground planes I preheated the area with hot air first and they desoldered perfectly.
I didn’t show it earlier but I did remove the keyboard connector and the audio jacks. I have an Amiga 1200 to recap in an upcoming episode, and I’ll show in more detail how I got these out without any damage in that video. Soldering this back in I like to move around to different points to stop heat building up too much. You can’t be too careful with plastic parts.
And lastly, after removing the remaining solder from the holes and the parts, the audio jacks are replaced.
It’s time to test.
There we go! Working great.
Just need to put it all back together, connect it back up, and test it out with all the bits inside.
To be thorough I ran through all of the tests in the Amiga test kit, including testing all the onboard and addon memory. All the sound tests. All the video tests. And the joystick and mouse tests. Everything passed with flying colours.
I better play something!
This computer, along with another Amiga 600, lots of Amiga 500’s, and many other computers (at the last count there are around 20 Commodore micros going in the auctions) will be yours to buy on October the 19th. On that day I will be hosting a 12 hour live stream where you can watch me gradually deteriorate into a tired old shell of a man trying to remember how words work. To help me through this marathon I will be joined by special guests from all around the world. This time there will be loads more than last year, with multiple people on during each slot and people coming and going throughout the day.
And all the time the auctions here in the UK and around the world will be ending and we can watch and see if we can get close to the fifteen thousand pounds the Befriending Scheme needs to buy some miniature donkeys. And it won’t just be computers and high ticket items up for sale. I have a stack of other smaller things to suit all budgets. Mugs, books, all kinds of bits and pieces I need to sort through and get ready for October. And if you would just like to make a donation to help us reach that huge and very scary target, you can do so at the just giving page which you can find in the description of this video and pinned as a comment. You’ll also soon be able to find all of the charity event details, including all the items being added to the huge list, on my own website more fun making it .co.uk
Thank you for watching and I will see you in the next one!

Is it possible to turn THIS battery acid destroyed Amiga 500 plus into £1000? For charity.

A while ago my friend Paul Universal retro boss gave me a couple of Amiga 500 plusses that were beyond simple and economical repair. And for quite a while they’ve lived in a plastic box in my workshop waiting for attention. Earlier this year, on a visit to the RMC cave, I ran into Rob “Peepo” Taylor of the Board Folk, and we briefly discussed his Amiga 500++ project. I expressed an interest and Rob offered to sell me a board at a super reasonable price.
When he later learned the Amiga I was going to be building on his board would be sold to raise money for charity, Rob sent me an extra board, and then donated the money I’d paid him to the charity I was raising money for! What a nice guy!
This October 19th will be the final day of this year’s charity fundraising for the amazing Befriending Scheme, you can find details in the description, and I would like to build a special machine to sell on that day. I think with the right parts inside and out this computer could raise a serious amount of money, in fact I think it could raise over a thousand pounds. That’s about $1300 US, or about 3 million Australian Dolleroos.
I’ll be using as many parts as I can from the two donor machines, and scrabbling around for the rest in my workshop, and also receiving some pretty spectacular donations along the way.
So let’s get building!
Both these boards are definitely repairable. I’ve seen the likes of GadgetUK Chris and Glen from CRG bring back boards in far worse condition than this. But the idea here is to make something I can sell for a lot of money. And selling a motherboard covered in bodge wires and nail varnish is not going to get the job done.
There are certainly some good parts on here, but I think all of the sockets will be heading to the bin. Many of them are single wipe, which is no good at all, and it doesn’t help that the Gary socket is missing a few teeth. The battery goop managed to get into all areas inside this machine, but the other one isn’t quite as bad, and I’m hopeful I’ll get one working set of components from both of these.
Today I will be using this beautiful purple and gold board. Long time viewers might remember one of the centrepieces of last year’s auctions was a ZX Spectrum with a purple motherboard and a smoked crystal case. Well this purple motherboard thing has started a bit of a trend! It helps that it looks absolutely stunning. And when I show you the case a bit later I think you will be very pleased to see that what we came up with for this build is not only in keeping with the theme started last year, it’s also drop dead gorgeous.

To maximise the amount of profit I can make when we auction this computer I’ll be salvaging as many components as possible. Right down to some of the passives.
These ceramic caps are axial types of all different values. It’s perfectly possible to buy these new, but that would waste precious charity money, so I’m removing them one at a time from the old board, testing them in my component tester, straightening the legs, and then soldering them into the new board. It doesn’t take too long and it really helps that all of the values for all of the components are printed on the silkscreen of the new 500++ boards. I think that’s a lovely touch.
There are a couple around the damaged area that are too far gone, in those cases I took the correct values from elsewhere on the second donor board.
After the caps I need to move onto the resistors. Now resistors are very cheap, and I should have everything I need in my highly organised stash. These are really not worth taking the time to salvage so I quickly work through the list, ticking them off the interactive bill of materials as I go. It’s slow, methodical work, and I enjoyed every minute of it.
After the resistors I worked my way through all the other components I could salvage, including the so-called Vidiot, or “Video Hybrid” board. I’ve heard this can be difficult to salvage and is easily damaged during removal. But I managed to get both of these removed from the two boards without visible damage.
These are filter capacitors. They were fun to remove, burning my fingers on just about every one of them.
Resistor arrays, ferrite beads, and diodes all followed. Which just left a few transistors to solder in place. And that was all of the passive components installed. I next installed sockets. Everywhere. And due to some of the legs being trimmed very short, where I had stock I installed turned pin type sockets. More on that later… Miscellaneous components like pin headers, the coil and crystal were all safely transplanted.
Interestingly this weird diode configuration here is not needed on the new board. Rob fixed the bodge that these were fixing on his revision. So the new diodes could just be installed as originally intended.
And then all of the connectors along the back edge were removed from the better scrap board and installed on the new one. I took some time to polish any metal parts that needed attention. These RCA audio jacks are looking a bit tired. I might swap them out later if I can find some nicer ones, but again, cost is a ruling factor here. I’m also a bit surprised they are both red! Would it have really cost you that much to put a red and white one in here Commodore? Anyway, it’s now looking almost complete and I’m really happy with how it’s coming along.
The donor board is now looking pretty empty! Just the memory and some logic chips near the battery damage. The 244’s already removed from this position were both destroyed by the battery leak. I have dim hopes for these 373’s. Removing one of them reveals tide marks from the corrosive gloop. I popped the 373’s into my lovely Retro Chip Tester Pro.
Here I am testing all of the memory and logic chips. It’s possible to test logic chips in one of the cheap minipro, tl866 type programmers, but I’ve found those can be unreliable.
I’m hoping the retro chip tester pro does a more thorough bout of tests, and while the interface can be a little bit clunky, compared to typing the chip into a search box, you quickly get used to how it works.
I tested the memory off camera and was very disappointed to discover that every single chip was faulty. Which seemed kind of unlikely. How could all of them be faulty? They weren’t fake too were they?!
And then I remembered! Along this side of the retro chip tester pro are some jumpers that need to be set when testing certain types of memory. I’d recently run into this whilst testing some 4164 drams from a commodore 64. Without the right jumper set the tests were unreliable. I’ll probably continue to forget about this and have the same facepalm moment every time it happens. But that’s definitely user error, the tester is brilliant.
With the jumper in place all the RAM tested good. Once I remembered where I’d stored all the custom chips I got those installed.
It looks great, but I’m not 100 percent happy with the sockets. The chips with short legs are not very securely held in place. The worst of them is this clock chip. I can just lift it out of the socket without any pressure at all. I really don’t want these to work their way loose in the post, so I think once this is tested and working I’ll remove all of the turned pin sockets and solder those chips directly to the board.
It’s time to switch it on and hope for an absence of magic smoke. And would you just look at that! It works!
Well that’s not quite the actual sequence of events.
What actually happened was I turned it on with the original 2.04 kickstart installed and it worked great. Then I upgraded the kickstart to a 3.1 version and it refused to boot. I checked everything. Swapped every custom chip on the board with known working ones, examined every solder joint, and in the end asked for help. I had lots of useful suggestions from the more fun making it discord members, link in the description, but the one that solved the problem was the person I really should have asked first. Rob Taylor recreated this board so he really should know a thing or two about it, and when I told him the symptoms he pointed me to a forum which explained the problem. This isn’t a fault in Rob’s design, it’s actually something missing from the original revision 8a motherboards. Possibly others too.
Over here there are a couple of spaces for resistor arrays marked RP106 and RP107. These pullup resistors for some of the address lines are not populated by default. Using the larger eprom for kickstart 3.1 means these address lines are required and so without these resistor packs the computer wont boot kickstart 3.1
I sourced a couple of these 4k7 packs and installed them, turned it on and it worked flawlessly.
It would be easy to stick this in its original case, give it a wipe down and then sell it on for charity. But that would be boring and a bit too easy. So instead…
I asked for some help from my amazing supporters to buy a few items to make these charity computers really special. There are quite a few of these new shiny things to see over the coming weeks, but the first one that I want to show you is this amazing crystal case bought by the group using my Kofi donations page. During this charity event all of the money donated there will be used to fund the builds. You might remember the crystal ZX Spectrum with purple motherboard from last year’s event. Well my friend Fuzzy Lee suggested we should do the same this year. Without spoiling future videos too much, this won’t be the only computer in these auctions with this colour scheme!
I have a few choices to make about what goes inside this machine. And the first is this metal shield. This one here is way beyond cleaning, probably not even painting could bring it back. But the other one isn’t too bad, and I spent a while polishing it to a shine. There are still splotches where corrosion ate into the surface, but it looks pretty decent. I took it along with me to show off at the Amiga Kickstart event in Nottingham earlier this year and there was quite a lot of interest. But a few people suggested the metal shield would be better off gone. And I have to agree. We want to see what’s inside this machine after all.
Ahh yes, the special edition yellow snow keyboard. As you can see here it works perfectly well. All I need to do is restore the colour with a spot of peroxide retrobriting. The sun is out and its ideal weather here in the UK for this. I don’t very often retrobrite things. For my own collection I don’t really mind if it has a bit of patina. But this machine needs to be good looking so I invested in a big tub of 12% food grade peroxide and decided to try the submersion method.
Now these keys were seriously yellowed and I wasn’t expecting miracles. And this is my first time using this method so I was kind of expecting it to go horribly wrong. And if you look at this picture of the keys in their bleach bath you can see there is an issue. The keys are floating. And if you look at some of them they have a pool of liquid on their surface. If left like that there would be a different colour patch at the end. Fortunately I regularly gave them a good stir with a stick, and managed to avoid catastrophe. But there are one or two slight marks that you can see if you look really close. But given that the keys look a million times better I think this is actually a win if you compare the end result to how they looked before. If I get time I might swap these out with a set of keys from one of my own machines if they’re in better condition.
Another conversation I had at Kickstart was with the lovely Chris “Cathers”. You will be hearing more about him in an upcoming episode as he donated something amazing for a very special project. No spoilers! If you want to see the huge list of amazing machines and other smaller items we will be selling for charity on October the 19th keep an eye on this and my second channel as I will be giving regular updates. Chris and I were chatting about the colour scheme of this Amiga, and especially about the keyboard. Most of this discussion was around the keyboard PCB which as you can see is nasty green, which doesn’t really go well with all the rest of the colour scheme. Chris pointed out that Dominik from The Digital Retro Bay (link in the description) had created a new keyboard controller PCB and that he had one on display in the next room in purple. Of course I rushed right over and was soon enquiring about it. Dominik explained he was still working out the wrinkles and it would be available in a couple of weeks.
And it’s now available and would be perfect for this build.
But part 1
I’ve decided I can’t go with this option. It’s a great board, and even includes built in hard drive activity with the original floppy LED doing double duty. But this is a bespoke item and a bit too expensive for the purposes of raising money for charity. I think something like this is for a money no object type of build.
But part 2
Rob Taylor has come to the rescue. It turns out that another thing Rob has recreated is the original PCB from a Mitsumi type Amiga 500 keyboard. And he just so happens to have one in purple! This is a recent development so if Rob manages to send that over in time I will show it at the end of this video. But all I will need to do is move all the components from this green board to the new one. Simple!
But the third. This is a good one though.
While I was talking to Cathers Chris at Kickstart. Ooh a tongue twister.
An idea formed. This grotty metal plate on the keyboard. I really should do something about that. And what I decided to do was paint it. A few coats of grey primer, and then a bunch of coats of gold.
It looks really good, I’m very happy with the finish so far. I need to give it another couple of coats and then a coat or three of clear to protect it. I also went a bit mad and sprayed the case for the floppy drive too. How cool is that with its crystal button!?
This is now looking amazing. But how can we make it better?
Well one of the big donations I recently received for this charity event was an Amiga 500 Terrible Fire TF536 from friend of the channel Colcuz Colin. Colin sent a whole heap of things including an Amiga 600 and Vic20 to sell in the auctions. You can see the unboxing of a frankly obscene amount of goodies over on my second channel, link up there in the corner. Thank you again Colin.
A TF536 is an Amiga 500 accelerator with a Motorola 68030 clocked at 50mhz. Making this a machine I would have personally traded body parts for back in the late 80’s. It also has 64mb of RAM onboard and an IDE hard drive connector. It’s a marvellous addition to this machine and my only problem with it? It’s green. But that’s ok, you can’t have everything can you?
Or can you.
Well no. You can’t, but you can get some of the way there. Another friend of the channel Andi, over at the Hack Build Restore youtube channel, offered to swap his own TF536 with this green one. Andi’s TF536 is black. Which isn’t purple, but it’s also not green and there are enough black things inside this machine that it doesn’t stand out like a hammered thumb.
So let’s put all of these pieces together now and marvel at what a beautiful machine it turned out to be.
And in a few short weeks you will be able to bid on this special Amiga 500 Plus, and a bunch of other machines, and maybe we can see it go for the £1000 estimate I plucked out of the air at the start.
For more details check for links in the description or my website morefunmakingit.co.uk where you can find the latest details.
Also if you would like to make a donation to the Just Giving page you can find a link to that near the top of the description and a pinned comment.
Thank you to everyone that contributed to this project. I hope this raises a huge amount of money for the Befriending Scheme.

The wonderful Bob Brenchley sent a big box of stuff for the charity event. Including a C64 with 1541 disc drive, a big heap of computer books, and a unique Timex 2068 that has a special story. More will follow on that machine at a later date, but for now enjoy the unboxing!

The ugly duckling of the retro computer world. 

Early in 1992 when I was sporting my beloved, but starting to creak, Amiga 500, Yes, that’s me. Commodore in all their wisdom, decided what the home micro computer market needed was pretty much what we already had, only smaller, and worser. The scorn us 500 owners poured on the new Amiga 600 was shameful, but fully deserved. I mean, it had the worst compatibility of the available machines without any meaningful upgrades to the silicon. All of the fancy expansions you could get for your A500 wouldn’t fit, and the num pad was missing! It felt, at the time, like a big backwards step and I, and everyone I knew, ignored it completely. In fact we went a step further and loathed that little Amiga.

So what about today? Did the ugly duckling turn into a beautiful swan?

Well, no, not really. It’s still a duck, but it’s grown into its face now, and in the right light is quite a handsome little wedge. 

This one here is a very nice specimen. Both on the outside, and on the inside. I was sent this computer by friend of the channel Colcuz, who donated it for the charity event I’m running later this year. You’ll be able to buy it and many other very special Commodore machines (and one lone mystery non-Commodore machine) in a huge auction to be run on the 14th of September. I’ll be live streaming with lots of special guests from all around the world of retro tech and gaming youtube for a marathon (for me) 12 hours. Together we can watch the auctions end and see how much money we can raise for the Befriending Scheme. Last year the final total was over £15k and we’re looking to beat that colossal amount this time around. I don’t want to start up the playground wars again, but can the Commodore fans really let those smelly Speccy oiks win this epic battle? 

Inside this lovely machine you can see it’s been upgraded with a few, er, upgrades. Here is an IDE to Compact Flash adapter taking care of hard drive duties. In the trapdoor is a ram expansion, bringing the onboard Chip Memory up from 1mb to 2mb. And here, clamped over the 68000 CPU is a clever board that adds fast memory to the system. And in the ROM socket is an upgraded kickstart 3.1. 

The expansions are not extravagant, but they do turn this into something much more useful in as much as an Amiga can be useful in the modern world. Basically it’s going to be a lot easier to play games on this than your bog standard A500. 

That older, and much larger, machine can be a bit of a faff to use. You need the right Agnus to allow enough chip memory to let you run games from hard drive. Oh, and connecting a hard drive usually entails purchasing something period correct like an A590 to plug into the side expansion connector. Not cheap or ideal. The alternative there is using a Pistorm and mounting hard drive images with that, which isn’t everyone’s cup of tea, or buying an expensive real hardware accelerator with on board IDE. And whilst it wasn’t a problem back in the late 80’s and early 90’s the A500 takes up a huge amount of desk space now. The 600 just fits nicely. Its cute. 

I would go so far as to say that the 600 is one of the best real Amiga’s to own now, here in the future. 

The other best Amiga to own now is of course the Raspberry Pi. 

Now I’ve had a chance to get to know this little dude I really want one for myself. And luckily, a while back, a very nice man called Neil, or Neildo, sent this one for me to add to my own collection. I like to think of this as a blank canvas. There are no upgrades fitted, it needs a good clean, and best of all its properly broken!

So where do we start?

Well I want to start with replacing all of the leaky electrolytic capacitors in here, and I want to try a new method of removing those pesky things. My preferred method is two soldering irons, but last time I melted the plastic on the audio ports which was quite upsetting. So this time I think to reduce the chance of melting anything I am going to use a combination of hammer and chisel. I have some lovely sharp chisels here in different sizes which should make getting into tight spaces quite easy. And various hammers to give me the perfect amount of control. 

Right. Let’s pop the top off and get the motherboard on the workbench. 

Wait a minute! All the caps have already been removed! Oh That’s a shame. Now we may never know how brilliant this hammer and chisel method could be!

Now we have the motherboard free I can show you the problem with this machine. On the back side there are two ceramic capacitors that have burnt up. Properly burned. The board substrate beneath is blackened and charred. These are decoupling caps which sit across the ground and 5v rails. If these have burned then it’s safe to say something bad happened to this machine. Now it is possible it’s just one of them went short, maybe this one here where all the burning is, and that took out the other one. But what’s really worrying is that there is still a 3 ohm short across ground and the 5v rail. So the likely thing is that more of these caps are damaged and causing the high resistance. Another possibility is that whatever happened with these caps also took out some of the precious chips on the other side. The very burned one, for instance, is directly underneath the 68000 CPU. For now I have to work on the assumption it’s just the caps and and with that in mind I took some resistance readings at various places across the board and compared the results, looking to see which side was more shorted than the other. This pointed to something over here on the right side of the back of the board, near to where the burned caps were. My next idea was to inject some low current, low voltage into the board and see what glowed. I took a spare power supply lead, worked out which wires were the ground and 5v, clipped my bench power supply to those, and then set the supply to 1v and 300mA. 

With my thermal camera ready I switched it on… And just down here this cap started to heat up. Not much, I wasn’t putting much power into it, but enough to show there was some unwanted resistance there. The simplest way to sort this out is to start pulling the decoupling caps off the board one at a time until the short disappears. I started with the caps close to where the resistance readings indicated. Ill hand you over to bench Lee to explain what I found.

Right this is where I’m up to I’ve removed three of these decoupling caps these three are off of the other side of these logic chips u47 u46 and u45 and c47 was a 30 ohm short and c46 was fine c45 was 2.8k this one up here which is behind the ROM C6 was 28 ohms and if I

measure across the rails now between ground and 5 volts I’m getting 61 ohms so my guess is that there’s well there are some more decoupling caps dotted around I reckon they’ve all been damaged so I’m going to take all of them off and replace all of them hopefully I’ve got enough 

Have a shave man. You’re almost as hairy as your mic.

Now, I’m not really used to working on this type of board, and I’m still very much learning how to use my hot air station, and so there follows a bit of a mistake.

You see, I started off with the air set to 350 degrees, as that’s usually enough for most things. But the caps were very reluctant to come off. So I assumed that was because the ground points on these caps were sucking away all the heat. But no, what was happening was the caps were hard to remove because Commodore had glued them to the board during the manufacturing process. This is actually quite common with surface mounted components. And it does make removing them a bit of a gamble. You don’t really want to pull too hard in case it’s not really ready to go and you rip a pad off, but you have to break the glue. 

And in the end I managed to delaminate the area around this cap. I wasn’t very happy with myself. That was the point where I worked out what was happening with the glue. 

After this I started taking the caps off with a soldering iron with a large blade tip. That was far easier, quicker, and safer. You live and learn. Please feel free to beat me up in the comments.

I worked my way through all of the decoupling caps on the front and back of the board, around 30 of them, testing the resistance as I went. And eventually with just about all of them off the board the resistance returned to something more in the expected range of around 130 ohms.

The caps in the middle are all still within spec, the 5 on the right are properly shorted at various resistance values. The pile on the left are still capacitors rather than resistors, but the capacitance is now either too high or too low. With this in mind I decided to replace the lot. After all, if these ones had failed, possibly for no reason other than they’re a bit old and rubbish, then the others were likely to follow suit. I ordered a 100 of them and waited for the postie. It’s possible this board is still beyond my ability to repair. If it suffered an overvoltage from a bad power supply at some point, causing those caps to fail, then it’s likely that overvoltage not only took out the caps, it probably took out some of the silicon also connected to the 5v rail. My best chance is it wasn’t an overvoltage, but maybe just one of the caps failed short and the others were just on their way too. The only way to know for sure is to install all the missing electrolytic caps, replace all the ceramic ones I removed, and switch it on to see what happens. So while I wait for the ceramics to arrive I’ll get these electrolytics fitted.

First job is to clean up all the pads. Neil did the right thing removing all these caps, saving this machine from further damage. There are signs of light electrolyte corrosion in a few places. Especially here around the reset circuit. From experience I will need to remove the 555 timer and these capacitors to clean underneath them.
The postie brought me some new 330nF caps and I set about putting them on the board.

And the moment of truth has arrived. Either this board is toast and good only for spares, or replacing with a raspberry pi, or I got really lucky and the only thing wrong was the caps had all gone bad. 

Woo hoo! It works!
Well. Mostly. There’s some glitching going on here with, it looks like, the red signal disappearing from the RGB image. I will just ignore it for now and hope it’s just a settling in thing. 

Some dyna blaster to test. A firm favourite from my old amiga days when I used to take my own A500 to the pub for multiplayer mayhem with my friends. Happy weird days. 

Next job on the list is to get this machine all cleaned up. It’s in a really bad state and I spent an evening stripping all the keys off the keyboard and giving everything a good scrub in soapy water. And underneath all that filth and dust it turned out there was a fantastic little machine in excellent condition! A few of the keys have slightly yellowed but a day out in the sun, with a leafcutter bee for company, evened that out enough for me. 

Now I have a nice condition, working Amiga 600, I need to put a few of those upgrades we saw earlier in the charity machine in this one to make it usable. 

First up is the trap door expansion. On my discord server I have a channel for swapping PCB’s, and I took Nick up on his offer of an Amiga 600 ram expansion to double the chip memory from 1 to 2mb. He also sent some of the smd passives and the clock chip he had as spares. Cheers Nick!
I still needed to source a connector, the battery holder, and a few resistors. Oh, and some memory. I asked again for help from my discord members and Fuzzy Lee offered me an old PC graphics card with the required memory chips on. Thank you Lee!

Getting the chips off this board shouldn’t be too tricky. And whilst it’s likely this card won’t ever be used again I think it’s sensible to do it non destructively, so I’m taping aluminium foil over the plastic bits to protect them.

It’s not a thick board so just 350 degrees and off they both pop. I’ll leave the other two here for safe keeping.

I’ve never worked with this type of chip before, and I hear they are a pain to solder, so this should be a fun learning experience!

I start off by cleaning the pads with IPA. And then adding some liquid flux. This isn’t a good move. Liquid flux tends to boil away very quickly and as I add some solder to the pads it’s not flowing. 

I replace the liquid flux with some better quality paste from a syringe and try again. This time the solder flows perfectly onto each pad.
Offering the chip up it doesn’t want to sit on the now raised pads. This feels like it might be tricky already. My plan is to reflow the pads with hot air and hope the chip settles in place. After a go with the hot air I can see it’s not going to work that way. And so I return to my trusty chisel tip iron and try a bit of drag soldering instead. It seems to work much better. A quick test with a pair of tweezers to see if any of the legs are moving, and I find there are one or two that are still loose. I think this just wants much more solder than I’m offering. Adding more flux and much more solder I go again.

Ok, that went much better. For the other chip I don’t bother with tinning the pads and just tac it in place and then drag along the legs with plenty of solder. Worked a treat. 

It’s nice and simple to see if the legs are properly connected by just testing for continuity between the pad and the top of the leg. Being careful not to push too hard and get a false positive reading. And I do find one leg that isn’t connected. A quick dab with the iron fixes it and all the others test good. A close look at all those lovely solder joints. No bridges and all perfectly attached.

Now, with the chips in place I can switch to the microscope to fit all the SMD passives. 

First up is this relatively large tantalum capacitor. I’m used to silkscreen markings indicating the orientation of components’ polarity, but there isn’t anything obvious on this board to show me which way round this cap goes. Unless that extra bit on the right side counts? I had to go look it up and I found a video that my pal Glen over at CRG had made building this exact same card. He also had to work out which way round this went. I’m still learning all these things and will probably forget quickly anyway, but thank goodness for youtube and amazing channels like Glens. He also showed which way the LED needed to be installed and saved me having to look that up/
Look! I even get my name on the components! How cool is that?

There were a couple of components not listed on the bill of materials, which meant I needed to examine the schematics to get their values. This resistor here for instance at R6 is a 1k. 

I do like SMD soldering, but that’s all done now. Time to fit the other bits.

Edge connector, battery holder, pin header and clock chip all fitted. Will it work? Lets plug it in and find out!

I recycled an old floppy pirate disc into an Amiga test kit disc and booted from that. 

The image is still a bit flickery. I don’t have time to fix that right now so I will probably look at that in another video. Possible on my second channel. But there is now 2mb of chip ram and it all tests good!

The last thing I need to do is fit the fast ram I purchased for this machine. This uses a plcc type socket press fitted over the 68000 CPU. It’s a bit hit and miss with these as to how well they sit on these chips. And this one just doesn’t go on very securely. This other one inside the charity Amiga 600 looks a much better fit and seems very secure. It also just about fits under the hard drive caddy. It might need a bit of metal filing off to make a better fit though. The other one will not fit under the caddy. I’m not sure I will leave this one inside my own 600. If I can live without the expanded memory I won’t use it. Another problem with these fast ram expansions for the 600 is fitting them means the PCMCIA slot doesn’t work. Which makes transferring files too and from the Amiga a lot less convenient.
The only other thing I need to install is a hard drive solution. I have plenty of these around and my friend Matt from the brilliant Tech Made Easy youtube channel kindly sent me a 4gb Compact flash card I can use with this machine. And I have this compact flash adapter which has been sitting in my spares bin waiting to be used for far too long. 

I can see myself using this amiga far more than my A500, 1200 or A500 plus. It’s just the perfect size to plonk on your desk and have a blast of sensible soccer or dune 2. It’s a cracking little machine. 

Thank you Neildo for sending it to me. I will treasure it forever. 

If you want your own amiga 600 you can bid on this one in September. And if you don’t manage to win, I have another one here you can bid on too!! This one was very recently given to me by Andrew Searle who popped round with a box of amazing donations for the charity and the channel. Andrew said this one was for me if I wanted it, but I said I already had a 600 and if he didn’t mind I would put this extra one in the charity auctions for someone else to own and hopefully raise a big lump of money for the befriending scheme!
This one has the notorious reset problem that happens when the caps leak over the reset circuit. I don’t know if it will make it into a video as I not long ago repaired a very similarly broken 600 in a video you can see in the corner of your screen. But the other thing with this machine is it’s very yellow, and I recently bought a big load of peroxide and I might give retrobrighting a go!  Keep an eye out here and on the second channel for updates about some of the amazing things I will have for sale on September the 14th. Put it in your diary! And if you just want to donate you can do so on the Just Giving page which you will find linked in the description. 

Lots more to come getting all these machines ready for you! See you soon!

It Changes EVERYTHING! (If you have an #AcornElectron with a broken ULA) But seriously, this is an important moment in retro and we should all be really grateful that people like @mogwaay and The Board Folk are giving us these things to keep our systems alive

All your computers are dying!

As we all strive to scratch our nostalgia itch, the effects of time passing on these old machines is a growing problem. Old plastics are breaking down, capacitors are drying out, and components that were never expected to last for more than a few years are spontaneously expiring just when we need them to give us our Jet Set Willy fix. Custom chips can be especially difficult to replace. Popular computers like the commodore 64 and Sinclair ZX Spectrum are well catered for and it’s now possible to build entirely new versions of those micros using brand new parts.

But what about some of the less popular machines?

How about the Acorn Electron? In the UK market this was meant to be the ZX Spectrum killer. And if a young Bilbo Baggins had managed to release it in time for the Christmas rush it might have been a big hit.

For viewers watching from other regions who might not be familiar with the little Elk, this machine was meant to be a cheap, cost reduced version of the BBC Micro.
What’s a BBC Micro? Oh come on America!
Ok, the BBC Micro can be thought of as the British Apple 2. I hope that makes things clear.
Now the thing about the 1981 BBC micro is its one of the few machines, certainly one of the few very successful machines, that you can build from scratch today using all off the shelf parts. Most other machines released after that time were designed with cost in mind, and one good way to reduce the cost of building a computer is to amalgamate as much of the logic as possible into fewer chips. Which is where ULA’s or uncommitted logic arrays enter the picture. The ZX Spectrum ULA combines almost all of these chips here into this single 40 pin package. 

Acorn took a very similar approach when they designed the Electron. A machine meant to compete at the value end of the market, but compatible (partially) with the much more expensive and very popular BBC Micro. 

But is there a risk attached to buying a condition unknown, works the last time I used it in 1986, electron from ebay? If any of the chips inside this machine are broken you don’t need to worry, not at all. All of them are easily replaced, and cheaply too. For example, this LM324N opamp here costs 98p. For ten! The logic is cheap, the ram is cheap, a rom can be replaced with a cheap eprom, and the CPU is a fairly standard 2mhz 6502. Yep. Nothing in here to worry about. What’s that? Oh don’t worry about that. That’s nothing. Just keep looking at all the other cheap chips.
Oh. Ok. Well that would be the infamous Acorn Electron ULA. This chip is, more than any other in here, the beating heart of this little machine. If this goes wrong, and they do, your Elk becomes an ornament. Quite a pretty one I think.

Currently the value of second hand electrons, is there a new value? Is pretty much as low as it will ever be. The last few auctions I can see on ebay sold for around £30. And I think it’s down to this: The risk of buying one with a faulty ULA is reasonably high. And if you have to replace the ULA the current going rate for one of those is around the same £30. Which makes no sense at all. The ULA you buy for £30 could expire almost immediately. It’s a frustrating state of affairs. And something that’s becoming more and more of a problem as they get older.
So what’s the answer?

Well the solution is to recreate the failing old tech, using new tech. As I mentioned at the start, the ZX Spectrum has new chips available, including the notorious ULA in that machine. This was reverse engineered by Chris Smith, and then other clever people such as Don Superfo came along and made a Spectrum that didn’t even need a ULA! There are also, more interestingly for the subject of this video, recreations that drop straight into the same socket. In the spectrums case the VLA82 by Charlie Ingley and the Nebula from Retroleum. But currently there isn’t one for the Acorn Electron.
Well. There wasn’t!
Chris Jaimesson, or Mogway, or Jamsoft, pick a name Chris! Is someone I’ve known through his positive interactions in the retro community, mostly on twitter, and more recently on my discord server. Which you should join. It’s awesome. Chris has come up with something that might be of use in bringing one of these destroyed motherboards back from oblivion. 

Let’s have a chat with him so he can tell us exactly what he’s been building in his techno cupboard. 

Why the Elk?

Well I didn’t have any experience with Electrons growing up we had two BBC’s when I was young and after picking up the nostalgia bug I was like oh I really fancy getting back into the Acorn world. So the first one that you got was it broken? Yes! I picked up one on the infamous Facebook sale where it was on a drive I saw pictures of this driveway covered in electrons and I picked it up and I was thankful the case was in really good condition it was very poorly packed it came in good condition but I had a little peek inside and yes no ULA and then it was Twitter user Scurvy Geek who got back to me and said gave me a little Ray of Hope and said well I think there’s a few people working on ULA Replacements so I kind of thought well could I fill a niche there is there just a bog basic like I just want the elk to be an elk could I just find a bog basic Electron replacement so I thought how hard can it be! But at just at that time I was looking at it I started Eric Schlaepfer who’s known as TubeTime who’s a reverse engineering wunderkind he’s done a lot of great stuff on the PC side of things he released the Graphics Gremlin which was an ISA card which could do CGA and MDA on an FPGA and he open sourced it entirely again and I could basically crib the basic FPGA plumbing from the Graphics Gremlin as my basis to build upon to do my own Spin and add the little bits I needed to get it going on the Electron for ULA so really I’m taking my I’m standing on the shoulders of  giants so I took David Banks’s amazing ULA code and I mixed it with the Graphics Gremlin and stuff and kind of smashed it together and that’s how it came about really.

Thank you Chris. And well done for bringing this project to the community.
Chris has very generously sent me a prototype to build and try out for myself. But before we get into that we need to look at these. 

All four of these boards were very kindly sent to me by Dave Hitchins who some time ago picked up a big score of Electron motherboards and various other parts. These are from a notorious haul of scrapped Acorn Electrons from a Facebook seller not very far from me. In fact my own Electron came from that very same seller. I think the story goes that these are originally  from a repair shop of some sort and many of these boards were scrapped for their parts. Which, looking at the condition of the four boards here, makes sense. When I bought my own machine from that seller it was complete but not working, I made a video about its repair which is probably in the corner of your screen right now. If I remembered. 

To give this new ULA a home I need a board to install it into.

Let’s take a closer look at these boards and try to pick a winner. 

There are three issue 6 and one issue 4 boards. 

The issue 4 board, at first glance, seems to be in the best condition. Only missing its CPU and ROM, IC17, and of course it’s ULA. Although the ULA socket is still here which is a good thing. Meaning there will be less chance of damage in this important area. Unfortunately there is some damage here near the CPU. I think I can resurrect that if I need to. That doesnt look too bad. There’s a missing pad there. I’ve labelled this one board number 1. And so far it seems to be promising. Number 2 is the first of the three issue 6 boards. This one is missing IC19, the ROM, the CPU and the ULA looks to have been ripped from the board. There are bits of metal sticking up and four of the pads are obviously missing. This is low on the list, but not impossible. All of the memory is present, but all of the decoupling caps looked to have been chopped off. I honestly don’t know what’s going on here at the keyboard connector. 

On the other side – well that just looks nasty. A huge glob of molten solder was just dumped here. No idea why. But the back of the ROM and CPU are looking grim and the ULA vias have suspicious bits of leg still hanging on. 

The top of board 3. The keyboard connector is the same grotty mess, the ROM is here! That’s a bonus. The CPU is missing, and at first glance there don’t seem to be any missing or ripped traces. The RAM is all missing but it seems to be neatly done. And the ULA is no longer there, but there seems to be less burning and devastation. And the back? Well this could clean up. There are no obvious missing pads or traces. But that green inner square of the ULA area does look a bit suspect. I wonder if this has delaminated. This one is on the maybe pile.

Board 4 is quite similar to 3. It has no ROM, but it does have all the RAM. Someone really didn’t like ceramic disc caps, did they! Maybe rats ate them. And the other side looks like it could be a winner too. I can’t see any obvious damage, but like all the others I will need to clean up and give all of these a thorough inspection before I decide which one to bring back.
And hopefully we have a candidate for resurrection. 

In the end I narrowed it down to board number 3. Even though it has this delamination it doesn’t seem to be affecting anything important.  the rest of the board looks in very good condition after a bit of cleaning.
I removed all of the chips, testing them all outside the board in my TL866 minipro programmer, which is not a perfect test, but should show up anything totally broken, and replacing the grotty keyboard connector, and then installed sockets in all the places where the chips needed to go. Just in case. 

A few passive components needed to be replaced. I borrowed these along with a set of memory chips from one of the other boards.

In the ULA position I used strips of turned pin headers to create a socket. And to make sure it was the right size and shape I did in fact desolder my own ULA to use as a guide, holding the pin headers in place whilst I soldered.

I switched it on with the original ULA installed and it worked!

So that’s a working board that’s missing a ULA.
Now we get to the interesting bit! Is it possible to build a working ULA using all these parts?

I’m a big fan of SMD soldering, but I have to say I was a little apprehensive to say the least when I saw the size of the components and how close together they are on the board. These are mostly 0402 parts, which means they are 0.04 inches long and 0.02 inches wide. Here is a banana for scale… 

Ok, something more sensible. Here is a normal quarter watt resistor.

Even with eye magnification I can’t reliably see these sized parts well enough, so it’s time for my trusty microscope. I say trusty, I actually lost quite a lot of footage recorded on the scope. Including all of the chip soldering, so not as trusty as I would like, but the work went pretty smoothly overall so you didn’t miss too much on all of the fun stuff. 

The kit Chris sent over comprises of 2 boards. The lower board is the one that has just a few components needing to be installed. I thought it would be a good idea to get my practice in on this board before turning to the top board where there was a lot more to do in a much tighter space. And being aware of the tiny scale of things here I switched to a tip I don’t normally use, hoping it would give me more precise control. I see lots of skilled technicians using these witches’ nose tips, and I just don’t know how they do it. I found it quite frustrating to use. Normally with a chisel tip I can control where the solder will be on the iron, but with this one it just doesn’t like to be near the pointy part of the tip. And being round I couldn’t get it to touch the pad and component at the same time. Before too long I switched back to my chisel tip and found that much easier to use, if a little bulky. In fact with some of the components I found it easier to flow some solder onto the pads first and then just blast it with hot air.

This bottom board carries lots of heavy traces, especially the ground and 5v points. This capacitor here refused to attach at the end close to that via. The solder flowed nicely onto the end of the cap but the iron couldn’t carry the heat into the pad. 

It looks soldered here, but if you look carefully you can’t see any shiny solder on the pad. And heating the other end? It wasn’t attached. I grabbed the heat gun and blasted it with 400 degrees hot air. Something I would need to do quite a few times further into the build.

These castellated resistor arrays were to prove very tricky. There’s just the one on this base  board but you’ll see a few more on the top board. And they gave me quite a few headaches.

I assumed they would be reasonably simple, a bit of drag soldering on both sides and job done. 

But that big heavy plane of copper to the right joining all four of the connections on that side was just sucking the heat right out of my iron. It was all a good learning experience though. 

Let’s try that again!
This time I want to get some solder onto the pads before attaching the part. That can help conduct the heat into the board. Two of them just don’t want to take the solder though, so I have bumped up the heat on the iron to 400 degrees. That’s got another one. And. Oh that looks a bit messy. Yeah, it’s not improving the more I try. Flux will sort this out though. Again with the hot air gun.

You can see the solder flowing and then instantly freezing again as soon as the air is not pointed right at that spot. I’m not sold on this one being attached so here is my multimeter in continuity mode. And testing from the top of the connections on the resistor they are all connected on the tricky side. 

As I said, all of the footage of the chip installations was sadly lost. But you can see the chips in lots of this footage and they are all perfectly installed. I checked each pin was securely attached, and tested between all of them with a multimeter, checking for bridges.

More resistor arrays. I’m getting a better flow going (ho ho). Although that pad under the 5 on RN1 here looks suspect. We might come back to this later!

That’s all the components fitted. 

Chris informed me this version of the board would require a couple of small bodges to work correctly. These have already been fixed in the most recent updated version. I just need a couple of wire links… and a capacitor. And one big chunky resistor over here on the side.

Next I went around every part of the board checking for shorts. I checked all the legs of the chips again, and all of these resistor arrays. I checked between ground and the various power rails and found no problems.

With the soldering completed I moved on to programming the FPGA. A process I’m not familiar with or comfortable explaining in detail here. Rest assured Chris has a comprehensive guide for all of this and more on his repository (link in the description). There are certain types of programmer that you can buy which make this process fairly simple, just a few command line commands and files in the right place to start with. I ordered one of those programmers from Amazon. Amazon delivered something totally different, I think these are stepper motor drivers. Chris said “don’t worry! I will order you the right thing and get it delivered tomorrow” A package arrived the next day from Amazon. Aaaaaand it was the stepper motor thingies again. He’d ordered the same thing I had!

And so we stepped into the murky world of Linux. Or at least that’s how it feels to me. I appreciate it’s a wonderful operating system and can do so many incredible things, is super stable, reliable, mostly free etc, but that doesnt mean I know how to use it.
Chris found a way to program the FPGA using a raspberry pi. Something he then added to his repository to help anyone thinking of building one of these. A proper programmer will be a simpler process, but to help keep costs down you can use just about any pi you have laying around. He actually did the testing on the original Pi 1. I had a few pi’s to choose from but thought having a keyboard already attached would be helpful so I opted for my pi400. 

Using the guides from Chris’ repository I attached the pi to the programming connectors on the ULA board. As I didn’t have the right gendered wires I ran them through a breadboard to the GPIO pins on the back of the pi400.  Then I double checked those connections. Then I checked them again. I installed Raspberry Pi OS and started following the guide Chris had provided. Then I got immediately lost and, close to fake tears, I messaged Chris asking for help. Chris is a brilliant bloke and spent a couple of hours guiding me through the process one command line at a time. And in the end we did it! 

It was finally complete!

Excited, I plugged it carefully into the test board and switched it on. 

My bench power supply immediately complained and went into voltage limiting protection. 

Oh no!

Was it something I did? I switched the FPGA board over to my own issue 4 Electron in which I’d already fitted some pin header strips for the original ULA. And this time it didn’t current limit. But it also didn’t work.

Some hours were spent pouring over both the now broken Electron motherboard, and the sadly non working ULA replacement.

On the issue 6 motherboard it took an embarrassingly long time to work out that a tantalum cap had given up and was shorting out the 5v rail directly to ground. A bit of measuring the relative resistance with a multimeter and finding out which side of the board was more shorted than the other pointed to this cap here. Removing it removed the short, and replacing it brought the electron back to life once more. 

But the ULA was still not working. 

During a very busy few days I went back and forth with Chris during snatched moments of time, with him feeding me clues on what to look for and where. Eventually, after a few red herrings, we found that two of the data lines were missing altogether, and using his excellent schematics I followed these lines from the FPGA, through the level shifter next to it, and into these resistor arrays. That’s not connected. Yep. Those pesky resistor arrays. Checking for continuity with the nearby pins I found one of them was not actually connected. I gave it a careful reflow and checked again. It still didn’t work. Well, chances are if one of them was not connected then others could be the same. I checked every connection from all of the resistor arrays around the board and found that quite a few of the connections were not making it through. There’s probably a better way to make these flow but in the end I got there with my chisel tip iron and hot air station. 

And then?

It’s working!

The case is beautiful it’s such a lovely little machine so I’m really hopeful that some of those can kind of come back to life and give people enjoyment. Secondly I’m also hoping that if an idiot like me can build one of these things then you know there’s hope other folks that might be inspired to give it a go too

So now what?

Well before I get to testing this I want to look at what I have here. This is my Acorn Electron I’ve had for a while now. It works fine, has an original ULA inside, and I don’t need to do anything with it. This Electron I recently bought from Julian from my Discord. It has a lovely case, in good condition, and the best thing about it is it doesnt work. This is going in the repair pile, and Im hoping it wont need a new ULA but if it does, well we know how to fix that now!
These four boards are a problem. I’ve already brought this issue 6 back to life, and the issue 4 should be fixable with a few bodge wires around the CPU area, but what about these other two? This one (number 4) is in pretty decent condition, just missing a load of decoupling capacitors. The board itself is pretty good. But this one…the aptly labelled number 2, has some heavy damage around the ULA area.. Its had a hard life. 

It’s all fixable. But there’s quite a lot of work here and in the end I would need a ULA, a CPU, a ROM, all the RAM, all these caps, and I would still only have a working board without a case to put it into. The case contains the most important part you need when using a computer, which is, of course, the keyboard. But is there another way? 

Well yes, there is! And as a bonus there’s something I can do about that destroyed motherboard too…

This is a PS2 keyboard adapter for the Acorn Electron. Kindly sent over by its creator Ian, who goes by the name GrandOldIan and is one of the brilliant group known as the Board Folk. This turns a bare board without a case into a pretty much fully functioning Acorn Electron. Albeit a bit nude and without a proper power supply. You can run an Electron just using a simple 5v power supply, but for tape functions you need the -5v that the original supply, er, supplies.
Ian also included a bare board so I can make up another one of these. It’s super clever, just slotting over the keyboard pins here. And you can still have an original keyboard connected with this set of pins here. The modulator, which is much less useful than it used to be, needs to be removed and the PS2 connector sits in the space where your RF cable used to plug in. It’s a very neat and clever device.

As well as the PS2 keyboard connector Ian sent this. 

This is an issue 4 recreated motherboard. The Elk. Again, from the marvellous Board Folk. I believe credit is due to Rob Peepo Taylor, who has been involved with many amazing board recreations. This one is an early version they’ve tested and works. It doesn’t include any credits to its creators on the silkscreen, but they kindly allowed me to give it a look over.
I intend on taking the worst board, that last issue 6 we looked at, and transplanting all of its parts over into this board. But that will be for a future video.

Right. Now I have a working ULA replacement in my rescued Acorn Electron, and a clever PS2 keyboard.  What can I actually do with it? Well pretty much everything you can do with a standard Acorn, plus a little bit more!

I don’t have a fancy SD card loading device for the electron, but I can load games via the tape port using my TZXDuino. Here is one of my favourites – Chuckie Egg. You might have seen Adrian playing this classic on his recent Electron video. 

And here is a very interesting one. Zalaga, which might be a clone of a game with a similar name… is a really good looking game by Nick Pelling and I really got into the blastemup action. But there’s something going on here that isn’t quite right. When things get really busy it looks like there are frames being skipped. It’s not really hurting the fun but Chris has come up with a clever fix for this. 

FPGA chips come with something called BRAM, or block ram. Only a tiny amount in modern terms, 8k in fact, on this particular chip. Which happens to be a rather useful amount in the context of a machine with just 32k of usable RAM. So when you press a combination of keys, in this case Ctrl Capslock and 2, turbo mode is activated.
Turbo mode uses that 8k of BRAM on the FPGA and maps it to the first 8k of address space on the Electron. This duplicates the effect of a retro hack from back in the day called the Slogger Turbo. That one did clever trickery to shadow the lower 8k of memory, allowing the CPU to access it at its full 2MHz speed. On top of this the 8k inside the FPGA is a full 8bits wide, unlike the 4bits of the real ram on the motherboard, so even more performance is gained. There are other things involving the way the ULA accesses RAM for display purposes that I really don’t fully understand, but these also give performance boosts. If you really want to know more about this stuff you should watch RetroBytes John’s excellent video on the Electron in which he explains everything about the Elk in his usual brilliant way. “Remember when I said I’d come back to Ram well this is the moment where we’re going to come back to Ram” Or go ask Chris. He will pretend it’s all very simple and be all modest but the man is basically a raving genius. His explanation for my simple brain was “It’s like fast cache ram on PC”

The results of pressing the turbo mode combination keys is quite startling. The game runs slightly faster in general, but when the action starts to get really busy the dropped frames become far less of a problem. They’re still there, but it doesn’t affect the gameplay now. And what a great game! This had me laughing like a loon! It’s made a fun but slightly glitchy game into an insanely fun and still a bit glitchy game.

I’ve tried a bunch of games on this replacement ULA and, for me, it has performed flawlessly. There are bound to be some edge cases that make it fall over but this is a brand new thing and I’m sure others will take it even further. 

It’s been a fantastic project to work on. Thank you Chris for letting me loose with your amazing widget. I had great fun building it and the satisfaction of bringing a scrap computer fully back to life just can’t be beaten. 

I hope you enjoyed the ride as much as I did! Thank you for watching. I’ll see you in the next one! (you are subscribed right?) Bye!