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| Macintosh SE PSU voltages out of specs |
Posted by: nvdeynde on 2019-02-13 04:17:26
I have several Mac SE PSU's where the voltages are far out of specs. All of them are recapped.
When measuring on the logic board FDD connector I get +4.75v and +12,75v with the voltage pot wide open in the PSU.
When testing the bare PSU with the analog board disconnected, I get +4.35 Volts and +11.80 volts.
What can be the cause of this ? Would it be the optocoupler or something else ?
The voltages remain stable from cold start but are way too low. I'm not comfortable with the voltage pot wide open as the +12v line is way too high and even then it can't reach 5 volts on it's +5v output.
The machine is a standard Mac SE with 4MB ram, no expansion boards or mods. Disconnecting the HDD and FDD doesn't make any difference.
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Posted by: OsvaL on 2020-06-21 03:58:19
Hi @nvdeynde did you find the solution to this issue?
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Posted by: nvdeynde on 2020-08-06 19:40:02
Hi @OsvaL No I didn't find the cause of the problem. It's weird that nobody else replied as I can't image I'm the only one with this problem.
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