Hello!
I recently successfully repaired two Apple PowerMac G4 MDD power supplies by swapping out bad caps, per excellent info found in various threads on this forum - yay!
I was doing testing on one of them, the ACBel API1PC36, with it's case open and had it setup outside of the PowerMac resting on the table with it's power connected to the system (power was also connected to a couple SCSI HDD drives, for a bit extra load). It was working fine, I shut down the system but did not unplug the PS from the power strip (and power strip was left on) so power was going into the PS.
I touched the edge of the PS case (as noted with the red arrow in the photo) while I was going to unplug it, and got quite a decent shock.
I certainly understand the danger of working with a PS with the case open, but of course am not expecting to get a shock from the grounded case. I'd been working with this PS for a bit like this, being extra careful to switch off the power strip it was plugged into before even touching the PS, unplugging it, etc. So now I'm not sure if this was a one off or if it was somehow doing this all along…
I need to figure out how I can tell whether there's live current running through the case/ground somehow. The PS still works completely normal.
It's of course possible that I may have simply accidentally touched something inside the case, especially since the side where I'd touched it is the AC side.
How can I properly tell with a multimeter whether there's some sort of current running through the case?
I measured voltage of the PS case and it's showing 2V when it's plugged in, though of course I had to connect the multimeter ground lead to something else (I connected it to either another PowerMac G4's case or a metal drive enclosure. I also get 2V when doing the same on another PS (a PowerMac G4 Samsung one) that I'm not getting shocked off of so not sure if that's expected.
Just in case, I also confirmed the electrical socket (and power strip) it was plugged into is properly grounded (and correct polarity if that matters).
I'm somewhat of a novice at power supply stuff, so any advice you may have, please be explicit.
Thanks!!
I recently successfully repaired two Apple PowerMac G4 MDD power supplies by swapping out bad caps, per excellent info found in various threads on this forum - yay!
I was doing testing on one of them, the ACBel API1PC36, with it's case open and had it setup outside of the PowerMac resting on the table with it's power connected to the system (power was also connected to a couple SCSI HDD drives, for a bit extra load). It was working fine, I shut down the system but did not unplug the PS from the power strip (and power strip was left on) so power was going into the PS.
I touched the edge of the PS case (as noted with the red arrow in the photo) while I was going to unplug it, and got quite a decent shock.
I certainly understand the danger of working with a PS with the case open, but of course am not expecting to get a shock from the grounded case. I'd been working with this PS for a bit like this, being extra careful to switch off the power strip it was plugged into before even touching the PS, unplugging it, etc. So now I'm not sure if this was a one off or if it was somehow doing this all along…
I need to figure out how I can tell whether there's live current running through the case/ground somehow. The PS still works completely normal.
It's of course possible that I may have simply accidentally touched something inside the case, especially since the side where I'd touched it is the AC side.
How can I properly tell with a multimeter whether there's some sort of current running through the case?
I measured voltage of the PS case and it's showing 2V when it's plugged in, though of course I had to connect the multimeter ground lead to something else (I connected it to either another PowerMac G4's case or a metal drive enclosure. I also get 2V when doing the same on another PS (a PowerMac G4 Samsung one) that I'm not getting shocked off of so not sure if that's expected.
Just in case, I also confirmed the electrical socket (and power strip) it was plugged into is properly grounded (and correct polarity if that matters).
I'm somewhat of a novice at power supply stuff, so any advice you may have, please be explicit.
Thanks!!
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