An Acorn Electron Repair

Now, this is a GOOD post day!
I’ve never owned or ever used an Acorn Electron in my life.
I’ll be flying blind here and will be asking for help along the way.
Thread starts here!

Case was in excellent condition. The only damage I can find anywhere is that power socket. It's a little more yellow than it appears in the pictures, but not terrible.

A pimple! Too long a screw. That's a shame.

Forgot to include the power socket pic.

A quick first peek inside. No case screws…
No socketed chips.
One capacitor looks to not be original. REALLY hoping that ribbon cable for the keyboard is OK

I'll be putting this to one side for a little while, other projects need finishing. I'll use the time to fact find and learn what I'm going to need.
Need a way to load games and programs too.

I'm weak, I know.
To be fair it just needed to be plugged in. I tested the power supply which was putting out close to the required +5 and – 5v.
But on the screen just some lines.
That they're regular might mean a ram problem?

Closeup of the screen. I'll have a quick search to see if this is a recognisable fault.

Doesn't draw a lot of current. I hope that's a good sign.

Here's the blob covered ULA soldered direct to the board. If this is the problem that's going to be painful.

The other side of that ULA is this. There's no other work been done on this board apart from…

This cap. It could be factory, but all the other caps are Unicon branded and this is… Well its a Wang. One for you @CommodoreBlog 😜

I assume this was a vain attempt to repair the Elk. It’s possible they just tried reflowing and then gave up when that didn’t work. Some of the pins barely have any solder. I’ll reflow these but I really doubt it’s an issue.

Went round with braid to quickly remove the old stuff. Lots and lots of flux still on this.

A brush with IPA and that muck is all gone. All the pads look in good condition. Some looked a little suspect, but they just had some of the old solder on them.

Reflowed. Looking shiny and clean.

Urgh.
I didn't think it would be that. Would have been nice if it was.
Incidentally, this is the screen with and without the keyboard connected.
Definitely putting this to one side now. Further work will be appearing in this thread in the future!

So today has been interesting. I bought this knowing it was likely broken. And that it was likely broken in an expensive way.
I've had so much help from everyone here, thank you all, you're amazing and I deeply appreciate how much interaction you give me.

It's only bloody working!

I printed out the relevant section of the schematics and started scoping around the CPU. That seemed to be working as expected. So I headed off south to the RAM

Pins 2 and 14 are D0 and D1. This is the reading on 3 of the ram chips.
It’s not great, but there are normal logic level readings there. Although not as many as you might hope.
But… So many butt’s.

But this is the reading on those same pins on the 4th chip.
Now, I might not have been completely convinced it was a bad RAM chip if this one had been bad in the same way as the others. But this one stuck out.

I wasn’t sure a Spectrum upper ram 4532 would work. But I couldn’t see the harm in trying. So I piggybacked one onto the suspect chip, switched it on, and then spent the next 5 minutes cackling to myself like a demented idiot.

And this is what the D0 line should look like…

It's too late to get the desoldering station out. I think I'll put this aside for now and come back to it when I'm ready to give it my full attention. Could make a decent little video. And who knows, it might have some more surprises up its little beige sleeves! Keyboard anyone?

Socket and new chip installed.
Working as expected!
Next I need to try the ram test program @leelegionsmith recommended.

The space bar on the keyboard is missing some parts that are to keep it straight and stable. I wonder if they can be 3d printed…

Nothing on Thingiverse…
Hmm, might have to design one myself.

Does anyone know if the tabs that insert into either end of the Elk space bar are the same as the ones on the BBC space bar? I have found a model for those.

Printed these and they work great! Keyboard feels fantastic with a working space bar.

Time to type on the memory test program.

OK. I only entered 8 lines and managed to get a memory test result!
Looks like something is still wrong here 🤔

This looks a bit hot. That's a trace of the address lines.

I took all the memory out to test.
And sadly it's all testing fine.
Something else is wrong.

This is the top of a pin on the ula. Looks very scabby. Is it a good idea to reflow these top pins on a blob ula?
Quite a few look like this.

This doesn't happen right away. Possibly failing cap somewhere?

Reflowed the solder on the top joints of the ULA.
Let's try this again!

Going well so far. Last time it had crashed by now.

The memory seems to be fixed. I didn't type in that program, but I do intend to load it when I get some cables to connect it to a TZXDuino.
Anyway! I thought I would replace the power socket. It's the same as the speccy ones so I had a new one handy.

Took the power board out and turned it over to find this!
Must have been bashed in with the PSU cable inserted. Board is broken, but not where it's really important. Obviously been worked on before.

I carefully removed as much of the solder as I could without weakening the area too much.

It's a bit of a mess. But I think it can be rebuilt.

I rescued the pad on the side pin and put it back in place so the solder would have something to flow onto.

Lots of solder under here. Should keep it from falling apart!

Flowed some hot glue around the socket with hot air to give it even more strength. Feels lovely and solid now.

Thank you @RetroCompShack
There's simply no better supplier of retro computer cables. Amazing price. Superb quality. Stunning service.
I ordered these at the weekend.
I don't know how you do it Ian. But, once again, thank you.
Now I can finish recording the Elk video!

I've had this TZXDuino for a while now. It was a little flaky on the Spectrum. Seems it will work with the Elk.
Note the @RetroCompShack cables plugged into ear and remote.

It's working!
Love the click of the relay as it tells the tape to start and stop.

2 things.
This plays very well. The lack of colour doesn't bother me.
I forgot I still don't have a speaker. Whoops!
It's on order. Should be here this week

Originally tweeted by More Fun Making It (Lee) (@ZZleeZZ) on 3 February 2022.