I'm working on an FSP250-50GUB FlexATX\1U style PSU from a DVR.
I don't know the history, only that it had seen rain, and I don't know for how long. I dried it out before powering it up and it seemed OK. But while the voltages seemed to be in spec, the system did not boot.
With another, standard ATX PSU, the system worked fine.
The capacitors were all OST, except a Rubycon, which looked like it may have been corroded\leaking. I replaced the lot.
However, testing it soon revealed another problem. An intermittent arcing noise from the primary side. I haven't managed to track down the exact component, but it seems to come from the PFC section.
I have checked the PSU in darkness and have been unable to see any spark or such.
Waving my scope probe over the PSU shows bursts of random noise across what are otherwise clean switching waveforms. My current theory is that the arcing component is dumping noise into the power supply so much so that it is propagating to the outputs, and I guess that the output voltages are so noisy that the system won't run.
I was going to try running the PSU without PFC, but the PWM and PFC controller are integrated into the same IC. Of course.
Does anyone have an idea of how to track down the source of the noise and fault? Visually everything seems fine, so far.
I don't know the history, only that it had seen rain, and I don't know for how long. I dried it out before powering it up and it seemed OK. But while the voltages seemed to be in spec, the system did not boot.
With another, standard ATX PSU, the system worked fine.
The capacitors were all OST, except a Rubycon, which looked like it may have been corroded\leaking. I replaced the lot.
However, testing it soon revealed another problem. An intermittent arcing noise from the primary side. I haven't managed to track down the exact component, but it seems to come from the PFC section.
I have checked the PSU in darkness and have been unable to see any spark or such.
Waving my scope probe over the PSU shows bursts of random noise across what are otherwise clean switching waveforms. My current theory is that the arcing component is dumping noise into the power supply so much so that it is propagating to the outputs, and I guess that the output voltages are so noisy that the system won't run.
I was going to try running the PSU without PFC, but the PWM and PFC controller are integrated into the same IC. Of course.
Does anyone have an idea of how to track down the source of the noise and fault? Visually everything seems fine, so far.
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