Point taken, but I was pretty sure it was an issue with getting battery power to the IC.
Had a close look this morning, and yes that's it. There's a 47 ohm resistor in the trace which supplies power to the CMOS chip, and it's literally the closest component to the battery on the whole board. There's a very short trace which runs to a via, and it had broken (invisibly). I just drilled out the via, installed a very short length of wire, bent it down to meet the resistor and soldered it. This fixed the problem.
Just had a quick look at IC33, and the outputs do seem to be following the inputs.
Had a close look this morning, and yes that's it. There's a 47 ohm resistor in the trace which supplies power to the CMOS chip, and it's literally the closest component to the battery on the whole board. There's a very short trace which runs to a via, and it had broken (invisibly). I just drilled out the via, installed a very short length of wire, bent it down to meet the resistor and soldered it. This fixed the problem.
Just had a quick look at IC33, and the outputs do seem to be following the inputs.
Statistics: Posted by jms2 — Sat Apr 12, 2025 11:04 am