No activity, T60 (BC238b) is broken (physically snapped). The battery has leaked
and there is some residue on R92, R93, R94, R95, T60 and C41.
First step is to clean up the battery damage and replace T60 (had to use a 237 transistor
which looks similar from data sheet)
OK, power up board, no joy. Try working MPU3 no joy either. Then I realise I’ve plugged
one of the ROMS in backwards on the ROM card. A mistake I will now have to pay for.
PROM 2 is toast!
Test with module from Exchanges Galore and the board boots and runs OK. Can’t test
switches yet, because the switches are stuck with grime and need cleaning.
The 7 segment LED is also not working so that will need replacing or rebuilding.
All PSU fuses are wrong so they have been replaced with the correct values. I’m actually
wondering whether the original fault was a stuck switch and that T60 was eaten through