(Topic ID: 315867)

High voltage on 5v rail on Pinbot

By bcg1976

84 days ago



Topic Stats

  • 4 posts
  • 2 Pinsiders participating
  • Latest reply 83 days ago by Tuukka
  • No one calls this topic a favorite

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#1 84 days ago

Pinbot doesn't boot. Looks like 12v rail is slightly under. -12v rail at -14v and the 5v rail on TP2 on the cpu board at 9v! Can hear an ac hum on the speakers.

Bridge rectifiers shot? What would cause a high 5v rail? Dead resistor?

Thanks,
Brad

#2 84 days ago

Most likely, shorted main transistor Q5 or bad regulator chip IC1 on power supply board.

I'm afraid the 9V has done some damage on the 5V logic

#3 84 days ago
Quoted from Tuukka:

Most likely, shorted main transistor Q5 or bad regulator chip IC1 on power supply board.
I'm afraid the 9V has done some damage on the 5V logic

Yeah, was fearing that. Just have to work through it.

Any tips on testing IC1? Or is it a common.part so just replace?

#4 83 days ago

It is a common part, so replace.

To prevent further damage, test the power supply with output connector removed, measure voltages at the board.

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