A blown fuse was only the beginning of Adrian Black’s attempt to revive a Commodore 1702 monitor. In a new 87-minute repair video, Adrian’s Digital Basement traces a stubborn fault through the CRT’s power and horizontal-deflection circuits, showing why a seemingly straightforward fuse replacement can turn into a much longer diagnosis.
Black first isolates the 125-volt B+ supply and tests it under a lamp load. A very low resistance on the deflection board leads him to a failed horizontal-output transistor, but replacing that part does not settle the matter: the monitor still behaves unpredictably and the replacement transistor fails too. He then compares parts and waveforms with a working 1702, before removing the flyback transformer and finding its ferrite core broken in several places. The video does not establish that the damaged core alone caused every failure; Black explicitly leaves that question open.
The useful lesson here is the diagnostic process, not a tidy “one bad part” ending. The repair also exposes a separate open resistor and an unresolved sync issue. For anyone maintaining original 8-bit computer displays, it is a detailed look at how interacting faults can mislead even careful testing. The video was published on 10 October 2026; watch the original on YouTube.
