Hello everyone,
PSU is made in late 2019 and seems barely used judging by the lack of dust on its innards.
+5Vsb is all right, grounding PS_on results in a relay clicking and nothing more, all outputs dead without even a flinch.
Checked inside, at first glance all seemed ok but then noticed something on the primary heatsink, which I promptly removed along with all its attached devices - there were clear signs of insulation breakdown above the C3D04060 diode. The device was overtightened from factory and the tab squished the sil-pad, it all was a matter of time, I guess.
When the discharge(s) occured, they were across the main caps - heatsink is connected to their negative terminals, and diode pin 1/tab (cathode) goes to their positive terminals. Since the caps were charged to more than 290V when I opened the PSU, it's clear that there wasn't a permanent short-circuit between the diode and heatsink (also confirmed this with my multimeter).
All the devices on the heatsink seem to be still functional - the two bridge rectifiers check out ok, the four mosfets aren't shorted but after charging their gates with the multimeter they only become slightly conductive (around .7 reading on the diode scale). The diode also reads about .8 (I'm guessing this is the forward voltage drop?) but this also might be ok given it's a high voltage diode. I'll check it tomorrow with 12 volts and a lightbulb, looking for advice for further testing the mosfets, and also where to further look for the culprit? Other than what I've described, everything looks perfect on the board.
PSU is made in late 2019 and seems barely used judging by the lack of dust on its innards.
+5Vsb is all right, grounding PS_on results in a relay clicking and nothing more, all outputs dead without even a flinch.
Checked inside, at first glance all seemed ok but then noticed something on the primary heatsink, which I promptly removed along with all its attached devices - there were clear signs of insulation breakdown above the C3D04060 diode. The device was overtightened from factory and the tab squished the sil-pad, it all was a matter of time, I guess.
When the discharge(s) occured, they were across the main caps - heatsink is connected to their negative terminals, and diode pin 1/tab (cathode) goes to their positive terminals. Since the caps were charged to more than 290V when I opened the PSU, it's clear that there wasn't a permanent short-circuit between the diode and heatsink (also confirmed this with my multimeter).
All the devices on the heatsink seem to be still functional - the two bridge rectifiers check out ok, the four mosfets aren't shorted but after charging their gates with the multimeter they only become slightly conductive (around .7 reading on the diode scale). The diode also reads about .8 (I'm guessing this is the forward voltage drop?) but this also might be ok given it's a high voltage diode. I'll check it tomorrow with 12 volts and a lightbulb, looking for advice for further testing the mosfets, and also where to further look for the culprit? Other than what I've described, everything looks perfect on the board.
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