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In this episode of More Fun Fixing It, I take on a Commodore 64 with a classic black screen fault and some concerning internal corrosion. After a quick physical fix for a missing keyboard spring, I dig into the diagnostics using the C64 analyzer cartridge. The repair quickly escalates as I discover a bad PLA, a faulty 6510 CPU, and multiple failing 4164 RAM chips. Watch as I work through the logic to determine if this “genuine teak” plastic-covered C64 is still a rescuable machine or destined to be a parts donor.

In this episode of More Fun Fixing It, I take a look at some game-changing diagnostic tools for the Commodore 64. I explore the new Commodore Repair Toolbox by Dennis (HovKlan), a comprehensive resource for board layouts, schematics, and oscilloscope traces. I also test the C64 Analyzer Cartridge V2 from uni64.com, putting it to work on several faulty machines to see if it can truly pinpoint dead PLAs and bad RAM. Check out the Commodore Repair Toolbox: https://github.com/HovKlan-DH/Commodore-Repair-Toolbox C64 Analyzer Cartridge: https://www.uni64.com/ Join our amazing community in the Retro Hardware Discord here: https://discord.gg/5fmPMzU

In this bonus video, I’m doing an AliExpress unbagging focused on tools and supplies for retro tech repairs. From USB-C Power Delivery decoys and flux dispensers to some interesting steel mesh for case repairs, I’m stocking up the workbench for future projects. Also a few random items, including a 72-hour router reset timer and some black hot melt glue. Links to items – some of these are affiliate links. Items featured: – USB-C PD Decoy triggers (9V, 12V, 20V) https://www.aliexpress.com/item/1005006400496390.html https://s.click.aliexpress.com/e/_c4t9u5cX – Liquid electrical tape https://s.click.aliexpress.com/e/_c4UdwtCf – Heat shrink solder sleeves https://s.click.aliexpress.com/e/_c3tR8GZH – Steel mesh for plastic repairs https://s.click.aliexpress.com/e/_c2RSKiOX – Copper wool tip cleaners https://www.aliexpress.com/item/1005007565625529.html – Silicone USB-C cables https://s.click.aliexpress.com/e/_c3xqVfwb – Black hot melt glue https://s.click.aliexpress.com/e/_c41L2k8F – SMD resistor sample book 0805 https://s.click.aliexpress.com/e/_c3giMlgn – UV Resin https://s.click.aliexpress.com/e/_c3giMlgn – Breadboard https://s.click.aliexpress.com/e/_c4P2LY9H – Flux extruder https://www.aliexpress.com/item/1005009236159113.html – Wifi router resetter https://s.click.aliexpress.com/e/_c3Q8uA55 – Cleaning brush https://www.aliexpress.com/item/1005010518106662.html -Terrible magnetic cable tidies https://www.aliexpress.com/item/1005008565155083.html – Heat shrink tubing https://www.aliexpress.com/item/1005008895688869.html

After a year of putting the Hakko FR-301 through its paces, it’s time for a rematch. I’ve assembled seven different desoldering tools—from the legendary (and expensive) Hakko to a suspiciously cheap £17 “fire hazard”—to see which one is the true king of vintage PCB repair. In this episode, I’m put these tools through the “Desoldering Hunger Games.” I’m testing heat-up times, maintenance requirements, and a brutal, unscientific desoldering test on a sacrificial Issue 2 ZX Spectrum board. On test: The costly Hakko FR-301 (and the Japanese import “hack”) The modded ZD-915 (Is the “Moo Gun” still the value king?) The surprisingly quiet Yihua 948 The Gaojie S-993A and the terrifying 845 Plus manual options like the Engineer SS-02 and the Yihua 929D WARNING! Working on vintage hardware requires care. Please don’t treat your working boards the way I treat this sacrificial Spectrum!

In this episode of More Fun Fixing It, we dive into the meticulous process of restoring Commodore 64 keyboards. Dealing with a batch of six keyboards spawned from five restored cases, I test each one to identify non-responsive keys and common issues like flaky space bars and sticky home keys. Watch as I demonstrate a full teardown, including the removal of the shift lock wires and those tiny brass screws that are the bane of every restorer’s life. This project also serves as the perfect field test for the WorkPro 3.7V electric precision screwdriver, which helps speed up the tedious process of removing dozens of fasteners. Key highlights include: – A “destructive” experiment to prove that C64 rubber pads are graphite-impregnated all the way through, meaning they can be safely cleaned with abrasives like sandpaper. – cleaning gold contact PCBs using isopropyl alcohol and nano sponges. – Tips on checking solder joints and reassembling the keyboard. Keyboard testing software: CRL Joystick and Keyboard Test and Diagnostics [2021]

In this episode, I’m repairing a ZX Spectrum Issue 3B that came from a batch of computers previously worked on by another technician. While it initially seemed like a straightforward fix, it turned into a deep dive into the data bus. After ruling out the ULA and CPU, I discovered that the signals on data lines 5 and 6 weren’t reaching a logic high. The culprit? Two partially failed RAM chips (IC20 and IC21) that were dragging the bus down. It’s a great example of why modern chip testers can’t always be trusted—both chips passed several external tests but failed immediately when put to work in the actual machine. Key moments in this repair: * Initial Triage: Identifying previous “bodges” and a poor composite mod. * Power Rail Checks: Testing for shorts and verifying the voltage regulator. * Diagnostics: Using the Steam Card Pro to pin down IC11 as a failure point. * Advanced Troubleshooting: Using an oscilloscope to identify weak data line signals. * The Solution: Testing pull-up resistor values and replacing the faulty lower RAM.

In this video, I’m returning to the topic of UV resins to share how my repair process for Commodore 64 cases has evolved. Thanks to feedback from the community, I’ve refined the techniques to be much faster and more effective than my previous methods. I walk through a step-by-step repair of a “wood grain” C64, demonstrating: * Case Clip Restoration: Using blue tack and UV resin to quickly replace missing or broken clips. * 3D Printed Screw Posts: A new method using 3D printed PETG sleeves to recreate broken case posts without the frustration of molds. * Motherboard Post Repair: Replacing snapped internal supports by anchoring new 3D printed posts with UV resin. Safety Note: Please remember that UV resin is toxic and an irritant. While I move quickly in this demonstration, you should always work in a well-ventilated area and wear protective gloves. You can find the 3D files for the replacement posts on Printables via the links below. Post sleeve STL: https://www.printables.com/model/1579158-commodore-c64-post-sleeve Motherboard standoff STL: https://www.printables.com/model/1579144-commodore-c64-motherboard-standoff-mount Resin Link (original out of stock – I have not tried this one myself)(Affiliate link): https://amzn.to/4qVw7kP The “Death Ray” UV Lamp I use: https://www.aliexpress.com/item/1005002859730199.html Safety First: Protective UV Glasses: (Affiliate link) https://amzn.to/3YNp0ON

It’s part two! I honestly gave up trying to fix this machine multiple times. But something just kept making me come back for more. Rest assured there are hours of footage I edited it off this, with a huge amount of work performed off camera too. And this one was supposed to be easy!

In this video, I build a dedicated Z80 CPU tester to help diagnose failed processors found during recent ZX81 and Spectrum repairs. This project focuses on identifying original NMOS versus later CMOS variants, which differ in power consumption, heat production, and undocumented behaviour. The build uses a red PCB from PCBWay and includes an SMD resistor modification to fit a specific footprint. After assembly, I test various Z80s from my parts bins, identifying several dead chips and units with simple bent pins. Important Note on the Current Jumper: The current jumper must be installed by default for the tester to function. While the instructions suggest removing it to measure current with a multimeter, the device will not run or show test activity without the jumper in place. Tester Limitations: This tool primarily exercises address lines using a small test program. Some complex faults, such as issues with the HALT line or other specific inputs/outputs, still require advanced diagnostic tools like the Backbit Chip Tester Pro

How far should you go when repairing a “reluctant” computer? We are about to find out! This ZX Spectrum, from the pile of computers that Paul Universal Retro Boss supplied for repair content, is very poorly. Black and white bars on the screen are not a great clue and diagnostics doesn’t help much either. So join me as I start the deep dive into this sick example of a ZX Spectrum 48k.