Re: Retired Texas TI99/4A engineer needs help please.
On a home 'console style' computer of that era I would think it would draw somewhere between 0.5A and 1A from the 5V rail alone. It's a shame you don't still have the computer, you could have tried running it up on a twin bench PSU (if you have one available) and that would have shown you that (a) the computer really was working and (b) how much current the machine really takes from each rail. The computer itself may also have its power requirements from each rail marked on a label, maybe ask the owner.
Ordinarily the majority of the current drawn should pass through the transistor, so when the transistor failed the load tried to draw what it wanted through the resistor alone.
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