Hello all, I'm fairly new to the Amstrad scene never having owned one at the time back in the 80s, I was a ZX Spectrum and then a BBC Micro child!
A friend of mine recently cleared out his garage and unearthed his CPC464 and green screen monitor and has passed it to me to see if I can get it working.
When I got it I was able to strip it down and give it a check over and clean before powering it up and took the chance to replace the two electrolytic caps. Initially, it turned its power LED on and gave no video output. Checking the RAM chips showed two of them were faulty so I got replacements and now I get a dark blue screen when powering on, but no more that that.
I have tried changing the 40007 ULA for a known good 40008 ULA, tried a new ROM and tried a new Z80, but still, the output is just a blue screen.
Can anyone suggest what I should be trying next? I can get it on the bench tomorrow and get the scope and multimeter out, but some hints as to what to start looking at would be appreciated.
Cheers!
Just as a small update, removing the sound chip hasn't helped, but looking at the RESET pin on the Z80 it seems to be held high all the time. Is this correct or should it actually be low? Worth replacing IC110 on suspicion?
The Reset line must remain high since it is active low.
Using a SPST (momentary switch) to briefly make contact with ground will reset the machine.
rpalmer
All fixed now. Turned out that while cleaning my soldering iron I must have flicked a blob of solder onto the board away from where I was working on the two electrolytics. I did a visual inspection of the board this morning and just spotted a tiny bridge between two vias in the video output side of things. Once that was cleared it works nicely and I've even had Chuckie Egg loaded up on the tape deck!
Thanks for the steer on the reset line, will remember that for future.