I had a CPC 464 which I that thought I would get round to seeing if I could repair. I had mentioned about this machine in the past and was told it was a faulty AY-3 Chip because of all the characters printing on the screen. My eyes are not to good :( but using a light with magnifying lens I managed(struggled) to remove the faulty chip. I have fitted a socket ready for a replacement chip. On removing the old chip I did damage 2 traces which run to the joystick port but I have repaired them with 2 links(wire). Anyway I thought that I would power it up with the chip removed and it still prints some 2 small lines of characters.
1st line 63RUN"
2nd Line a few numbers then symbols but then this deletes its self just leaving the 63RUN"
Should this be doing this with the Ay chip removed?
I have not tried a different AY chip yet
No, which means that something more than the AY is broken, most likely the 8255 or even the Z80.
Bryce.
I don't think it is the Z80 as I am sure I changed this originally and the 40010 for working known working ones when I did'nt know about the AY chip. I will have another look tonight. So my struggle to remove the Ay was in vain :(