Commodore 64 Black Screen Triple Challenge (Part 2) - YouTube
Commodore 64: how to repair it, step by step
Some more Commodore 64 board repairs, this time the later shortboard (ASSY 250469) - there's eight in this article (serial/cassette/user port faults, black screen, shimmering colours, random crashes, etc), I hope it's
C64 Black Screen Repair - Part One - YouTube
Commodore Plus /4 - Black Screen Repair and Testing - YouTube
RetroTInk 2x Pro & Commodore 64 – white line left hand side of image – VideoGamePerfection.com