Your issues definitely look like heat-related... even if there's no thermal shutdown device.
Just a thought: maybe there's some metallic piece (or solder joint) which dilates on heat and ends up shorting some power lines, forcing shutdown? The problem could reside on the power push-button at the back of the computer...
A somewhat unrelated note: my Dad's 7500 was experiencing some random power-UPs, from a few seconds after shutdown, to hours or even days later, even in the middle of the night -- crazy! I tried everything described here to solve the issue, to no avail -- even the "defibrillation" procedure 8-o
...eventually, I solved the problem by replacing the ADB keyboard -- seems like it shorted the power-on signal randomly xx(
Just a thought: maybe there's some metallic piece (or solder joint) which dilates on heat and ends up shorting some power lines, forcing shutdown? The problem could reside on the power push-button at the back of the computer...
A somewhat unrelated note: my Dad's 7500 was experiencing some random power-UPs, from a few seconds after shutdown, to hours or even days later, even in the middle of the night -- crazy! I tried everything described here to solve the issue, to no avail -- even the "defibrillation" procedure 8-o
...eventually, I solved the problem by replacing the ADB keyboard -- seems like it shorted the power-on signal randomly xx(