The famous grey screen black frame issue.

[eto]

If Amstrad diagnostics reports the same ICs you should check the connections of all RAM IC pins and all the MUX IC pins.

I once soldered sockets and bent one of the socket pins inwards. I didn't see that and had that one IC reporting issues. 

The same could happen if you accidentally removed a pad. Also happened once to me and the IC then was reported dead. Thankfully that could be fixed easily with a wire.

Have you soldered your 2nd RAM bank also? If not it could make sense to easily force the 6128 to use the 2nd RAM bank as the primary bank and see if the error is still present. 

[oyshals]

If Amstrad diagnostics reports the same ICs you should check the connections of all RAM IC pins and all the MUX IC pins.

I once soldered sockets and bent one of the socket pins inwards. I didn't see that and had that one IC reporting issues.

The same could happen if you accidentally removed a pad. Also happened once to me and the IC then was reported dead. Thankfully that could be fixed easily with a wire.

Have you soldered your 2nd RAM bank also? If not it could make sense to easily force the 6128 to use the 2nd RAM bank as the primary bank and see if the error is still present.

Thanks! Making some small progress. Replaced one of the sockets for the MUX today, cleaned the pads more thoroughly this time. No broken pads. Will take my time with this, babysteps.

Looking through my workshop to find wires thin enough to make the "fal-socket".

The screen issue i 90% certain to be the video connector or cable. Will try to reflow the solderings on this one later.

[oyshals]

Been checking traces, and have replaced the MUX chips and sockets. No damage found. Having some trouble starting it, almost like it has to "warm up", will post pictures of this later. Always same result when running diagnostic, ram chip 1 and 3 working, none of the other even when swapping. Been looking in the schematics to see if there is something special with those two.

Might be a power issue though, I seem to have worn out the new power socket already, so will try to replace it again.

I'm also thinking that the disc controller caused the boot to crash, but something else corrupted the disc controller, thereby causing the crash. Thinking of maybe removing a few more of the IC's on the disc part of the board. In that case, would I still be able to initialize the diagnostic's rom?

[Rabs]

Have you traced data out pin 14 from each RAM IC to the buffer latch IC114?

Still looks like you just have some bad traces on the data lines associated the RAM.

[oyshals]

Will double check tomorrow, hopefully I will find something. At least I have two to compare with now 👍

[oyshals]

Haven't given up, just taken a longer break. Will start checking capacitators when I resume, due to the "start up delay" varying voltages, and lack of broken tracks. 

Will probably be a few months yet, as I've taken on a few easier projects, restoring a few PC's I found in my parents garage. Will update when I resume work on the CPC 😊