Hi All,
due to several threads in the past and present discussing over-voltage and reversed voltage on a CPC, I thought I'd put a short guide here. This list in only for over-voltage, not reversed voltage.
Raising the voltage slowly:
5V - All is fine.
5.5V - Still pretty much ok, but the 74LSxx, AY, CRTC, Z80 and FDC are starting to feel the pain.
6V - The 74HCTxx are also starting to get hot, but nothing has failed yet.
7V - The 8255 and PAL are at their limit, the parts listed in 5.5V above are starting to fail.
7.5V - The RAM ICs have reached their limit, but most of the parts in the 5.5V list will have already died.
12V - Everything is failing, just the analogue ICs are still holding out.
15V - The LA4140 in the tape deck finally gives up.
30V - There's probably smoke coming out somewhere and even some of the capacitors are starting to pop. The only surviving chip is the LA6324
36V - The LA6324 fails.
Instant Voltage:
Although the list above seems to suggest that the Logic / Z80 / CRTC etc would die before the RAM, this isn't the case if you were to connect 9V to the CPC. Althought they can survive 7.5V and the Logic only manages about 5.5 to 6V, they tend to fail faster. So 9V would probably kill the RAM first and (if you're really lucky) the failed RAM might even protect the other ICs by dropping enough voltage.
Either way, connecting more than 5V to the CPC is generally a bad idea. Reversing the voltage (even at 5V) also isn't advised. This will also kill the ICs pretty quickly, but again, the RAM ICs seem to be most sensitive to this and will most likely fail first.
Bryce.
