Trying to repair Mark's Amstrad CPC464: Part 1
23Mark dropped his CPC464 board off (MC0002C) on the way from Sydney to Cairns, a roughly 2600km drive.
It's an earlier board with a 40010 gate array. There is no video output.
Checking the RGBS signals out of the 40010 showed nothing.
Checking the clock and some other signals on the Z80 also showed no activity.
So I then checked the clock - I can see the CK16 pin on the 40010 is active, although appears "irregular". Next I checked the outputs on the 74HCU04 (hex inverter) - the first two gates showed output, but the remaining gates show no activity.
I've got a schematic that shows the 40007 but this is slightly different to the 40010. Maybe I'm going down a red herring rabbit hole ... but I'm still wondering why the clock isn't working - I'm assuming we need a valid clock into the Z80 for "something" to happen at least ...
Oh, and I also compare various CPC464 board types ... from the original long board to the final sub-half length board.