This Commodore 64 main board had so many things wrong with it, it was a fun challenge to get it working again. Previous owner(s) had caused damage to the board by removing chips, which adds an extra layer of difficulty to troubleshooting. It all starts with the dead test cartridge doing nothing. In this video, I show my techniques for troubleshooting and fixing all of the problems. --- Video Links Special thanks to IZ8DWF who has given me great advice on repairs: https://www.youtube.com/channel/UCgwkF_tMMsury1DeszD4Ohg C64 main board schematics: http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/index.html Diode Symbols: https://www.rapidtables.com/electric/Diode_Symbols.html --- Tools Deoxit D5: https://amzn.to/2VvOKy1 http://store.caig.com/s.nl/it.A/id.1602/.f Jonard Tools EX-2 Chip Extractor: https://amzn.to/2VazxDS https://www.jonard.com/Products/EX-2-DIP-IC-Extractor-24-40-Pins Wiha Chip Lifter: https://amzn.to/3a9ftWw https://www.wihatools.com/precision-chip-lifter O-Ring Pick Set: (I use these to lift chips off boards) https://amzn.to/3a9x54J Elenco Electronics LP-560 Logic Probe: https://amzn.to/2VrT5lW Hakko FR301 Desoldering Iron: https://amzn.to/2ye6xC0 Rigol DS1054Z Four Channel Oscilloscope: https://www.rigolna.com/products/digital-oscilloscopes/1000z/ Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier: https://amzn.to/3adRbuy TL866II Plus Chip Tester and EPROM programmer: (The MiniPro) https://amzn.to/2wG4tlP https://www.aliexpress.com/item/33000308958.html TS100 Soldering Iron: https://amzn.to/2K36dJ5 https://www.ebay.com/itm/TS100-65W-MINI-Digital-OLED-Programmable-Soldering-Iron-Anti-static-Structure/113382669853 EEVBlog 121GW Multimeter: https://www.eevblog.com/product/121gw/ DSLogic Basic Logic Analyzer: https://amzn.to/2RDSDQw https://www.ebay.com/itm/USB-Logic-DSLogic-Basic-Analyzer-16Ch-100MHz-4Ch-400MHz-Xilinx-Spartan-6-FPGA/202543965672 Magnetic Screw Holder: https://amzn.to/3b8LOhG https://www.harborfreight.com/4-inch-magnetic-parts-tray-90566.html Universal ZIP sockets: (clones, used on my ZIF-64 test machine) https://www.ebay.com/itm/14-16-18-20-24-28-32-40-pin-IC-Test-Universal-ZIF-Socket-Fs/303206721971 RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI) http://www.retrotink.com/ Plato (Clone) Side Cutters: (order five) https://www.ebay.com/itm/1-2-5-10PCS-Micro-Scissor-125mm-PLATO-170-Electronics-Cutter-Side-Cutting-Pliers/163458746184 Heat Sinks: https://www.aliexpress.com/item/32537183709.html Little squeezy bottles: (available elsewhere too) https://amzn.to/3b8LOOI --- Links My GitHub repository: https://github.com/misterblack1?tab=repositories Commodore Computer Club (of Portland, Oregon and Vancouver, Washington) https://www.commodorecomputerclub.com/ Tivoo Pixel Art Display seen in my videos: https://www.amazon.com/Divoom-Tivoo-red-Tivoo-Bluetooth-Speaker/dp/B07CVGYPTV --- C64 Stuff JaffyDOS: http://blog.worldofjani.com/?p=3544 C64 Test Harness I use: https://www.youtube.com/watch?v=szSzA6T4Kdw C64 Homebrew cartridge PCB: (used for the DeadTest / Diag Cart I use) https://www.ebay.com/itm/Commodore-64-C64-C128-NEW-bare-HomeBrew-DEVelopment-cartridge-board-8-32k-2019/162430154398 EasyFlash 3 Multi-Cart: http://store.go4retro.com/easyflash-3/ --- Instructional videos My video on damage-free chip removal: https://www.youtube.com/watch?v=XQVjwPsVFd8 --- Music Intro music by: Nathan Divino @itsnathandivino Outro Music: Abyss by | e s c p | https://escp-music.bandcamp.com/ Music promoted by https://www.free-stock-music.com/ Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/ --- Image Credits None