In this latest installment of Tim’s Retro Corner, Tim tackles a Commodore 64 exhibiting the classic “black screen” symptom. The computer, a breadbin-style model, arrived from a viewer named Brian who reported it as non-functional. Tim’s first visual inspection revealed typical signs of age and previous repairs, including broken warranty seals and obvious markings on replaced RAM chips.
Choosing safety first, Tim opted to bypass the original, aged power supply, using a reliable modern one instead. Upon initial startup, the infamous black screen appeared—confirming the reported issue. To diagnose further, Tim utilized a dead-test cartridge, revealing possible memory or PLA issues. However, the diagnostic cartridge failed to start, suggesting a problem with the kernel ROM.
Testing this theory, Tim swapped out the suspect ROM with one from another machine, confirming the faulty kernel ROM as the culprit. Following this successful identification, Tim proceeded with additional testing and cleaning of the motherboard, paying special attention to potentially problematic areas such as the user port and VIC chip connections.
After thorough cleaning, re-soldering connections around the VIC chip, and applying fresh thermal paste, the Commodore 64 was stable again. Tim enhanced the longevity of the repaired unit by installing adhesive heat sinks on crucial chips, reducing overheating risks.
Tim didn’t stop there; he also constructed a handy dummy-load tester for Commodore power supplies, crucial for identifying potentially damaging voltage regulator failures. By clearly marking tested components, Tim ensures future users have an accurate history of each piece of equipment.
Viewers interested in detailed retro repair techniques, practical diagnostic methods, or those simply curious about breathing life back into vintage computing gear will find Tim’s Retro Corner both informative and engaging.
