C128 Diagnostic Instruction and Troubleshooting Manual is Commodore’s service manual for using the C128 diagnostic cartridge and test harness. It explains setup, diagnostic startup, memory/ROM/I/O/sound tests, error meanings, and step-by-step troubleshooting for power, reset, clocks, video, RAM, CPUs, PLA, MMU, VIC, VDC, and CIA chips.

Commodore 128 Troubleshooting & Repair is a repair guide for diagnosing and fixing Commodore 128 hardware problems. It explains the C128’s main subsystems, basic electronics, troubleshooting tools, symptom-based repair procedures, video/keyboard/I/O problems, preventive maintenance, and reference appendices with pinouts, board layouts, ports, specs, and keyboard codes.

Troubleshooting and Repairing Your Commodore 128 by Art Margolis is a detailed hardware repair manual for the Commodore 128. It explains how to diagnose problems by symptoms, disassemble the computer, locate and replace chips, test logic circuits, troubleshoot memory, video, sound, I/O, clock, bus, and power-supply issues, and use test-point charts and schematics to track faults.