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Old 05-04-2022, 01:37 PM   #1
Join Date: Jan 2022
City & State: Cluj-Napoca
My Country: Romania
Line Voltage: 234.6V 50.0Hz right now
I'm a: Knowledge Seeker
Posts: 24
Default ESR 0.6Ω capacitance -15% absolute must change?

I have one (of 3) hot swap Supermicro/Ablecom PWS-0050 SP382-TS server PSU that is mal functioning. Supermicro IPMI reports it as bad and led is orange on.

I took it apart tested transistors, diodes, capacitor but haven't found the problem. I'm a beginner.

In standby I have 5VSB, but not 12VSB, nor 3.3VSB. Here is the PSU Pinot:

There are 3 x 400V, 100uF capacitors on the primary side.

They measure:

- capacitance 85-86 uF
- ESR around 0.55 - 0.65 Ω (I've subtracted 0.15Ω that I measure when I connect my leads together)

I know it's a good practice to change them. But could this explain the whole problem? Or these are workables ranges?

Based on the physical dimension, the 3 caps are a bit expensive if not ordered from China. That's why I'm avoiding to quickly change them.

What do you think?
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