In this video from TheRetroChannel, what looked like a simple Commodore 64 repair quickly turned into a marathon of frustration. The patient? A shortboard C64, showing signs of a RAM fault — random memory counts, black screen, and glitchy behavior.
Initial tests ruled out the modern power supply, leaving the motherboard itself as the main suspect. Dead test cartridges revealed all bits bad, but with some odd clues — including a garbled BASIC screen and changing byte counts, suggesting an addressing fault rather than bad RAM.
Piece by piece, the usual suspects were swapped or tested: RAM chips, character ROM, CIA chips (one of which had a broken leg but was repairable), and even the VIC-II video chip — all tested fine or replaced with no improvement.
An unexpected discovery was a missing 4066 IC, cut out by a previous owner. After replacing it, the problem remained. With nearly every possibility exhausted, the attention now turns to the Super PLA — a rare but possible failure.
The repair ends (for now) with the machine still broken, leaving the Super PLA and perhaps the remaining logic chips as the final suspects.
