BBC Master 128 repair - part 3
So the current state of play is that IC42 (which was a VC2069) has been replaced with a VC2023 borrowed from a model B. They’re pin compatible (and I believe functionally compatible). I now have: pin 8 – 16Mhz in pin 7 – 8MHz out pin 6 – 4MHz out pin 5 – 2MHz out pin 4 – 1MHz out BUT, the 2MHz out, while it makes it to IC34 pin 2, doesn’t make it to IC28 pin 3, which results in no 1MHZE signal being generated – and that’s used by the VIA’s, they keyboard, and in various other places....