I hit a bit of a snag in my plan. The “known good” VIC-20 main board I had turned out to be not so good. When I plugged it in to test it, the video output was garbled! Fortunately, the original main board turned out to be ok. Just had to adjust the potentiometers controlling the video signal 1E81195F-27D4-4A98-9659-C07BB06EAC39.jpg A204BA44-0975-49AC-BECA-102941D315DC.jpg