Model:Sunsung "make your life beautiful"
SN-W450 ATX
Sticker: 0604 005 263
Fault: Buzzing heard with the psu powered on without load. Probably still buzzing with load but intake fan too noisy to hear.
Background: Work colleague asked me to take a look at this psu which he has had for a few years, he mentioned the buzzing and the fact it looked quite dusty - this was an understatement.
Testing / observations:
PSU (cheap tester) showed the following rail voltages:
+3.3 = 3.3v
+5 = 5.2v
+12v1 = 12.1v
+12v2 = 12.1v
-12v = 11.6v
5vsb = 5.1
PSG=280ms (not sure what this means)
Once I'd removed a lot of the dust I saw that caps C19 & C20 were bulging. These are JEE caps with a value of 2200UF and 10 volts. Tested values were ESR of 2.2 & 2.3, no capacitance value available - I am assuming it was too low. I still have to measure a few of the other caps (Canicon and Su'Scon)
At this stage I had a sniff and I could smell that burnt plastic smell. I unscrewed the secondary board which sat upside down above the 2 large black caps. This didn't look so good - the pcb was very discoloured around 2 resisters. I need some help trying to work out the values of these resisters as the colour bands are badly burnt. There is also no continuity on either of the resisters.
I will carry on testing the remaining resisters that I can work the values out on. The general layout on this psu seems quite poor and everything seems very tightly squeezed in. Add copious amounts of dust and this can't make for a long service life.
Photo's to follow shortly.

Sticker: 0604 005 263
Fault: Buzzing heard with the psu powered on without load. Probably still buzzing with load but intake fan too noisy to hear.
Background: Work colleague asked me to take a look at this psu which he has had for a few years, he mentioned the buzzing and the fact it looked quite dusty - this was an understatement.
Testing / observations:
PSU (cheap tester) showed the following rail voltages:
+3.3 = 3.3v
+5 = 5.2v
+12v1 = 12.1v
+12v2 = 12.1v
-12v = 11.6v
5vsb = 5.1
PSG=280ms (not sure what this means)
Once I'd removed a lot of the dust I saw that caps C19 & C20 were bulging. These are JEE caps with a value of 2200UF and 10 volts. Tested values were ESR of 2.2 & 2.3, no capacitance value available - I am assuming it was too low. I still have to measure a few of the other caps (Canicon and Su'Scon)
At this stage I had a sniff and I could smell that burnt plastic smell. I unscrewed the secondary board which sat upside down above the 2 large black caps. This didn't look so good - the pcb was very discoloured around 2 resisters. I need some help trying to work out the values of these resisters as the colour bands are badly burnt. There is also no continuity on either of the resisters.
I will carry on testing the remaining resisters that I can work the values out on. The general layout on this psu seems quite poor and everything seems very tightly squeezed in. Add copious amounts of dust and this can't make for a long service life.
Photo's to follow shortly.
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