Quoted from Neal_W:Yes.
IMO - First test would be to remove all chips that are in sockets (ROM/RAM/CPU,etc) and see if the 5v is OK.
Bingo. First order of business is to find out what is dragging your 5VDC down.
Any chip on the MPU board could be the culprit.
Start with the easy techniques as Neal_W mentioned by removing socketed chips.
After that, leave the board powered for a while. Place your finger on each chip. Does one of them seem abnormally hot?
After that, you are left with educated guesses, and removing chips one by one.
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Chris Hibler - CARGPB #31
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