Hi,
I want to restore one old PSU. I found the main reason to not working. It was small cap (100uF/25V) on the Vdc bus going to the PWM controller. I replaced the cap with 470uF/25V (don't have currently 100uF) and PSU now works, tested under load with old GPU (ATi HD5830) and Furmark software. The replaced cap doesn't have any external signs of malfunction, even with capacitance meter is value is OK. But with it Vdc bus is ~11V and adding a small value like 4.7uF put the bus right, where it should be ~15.5V.
What currently doesn't like is the spikes on 12V and 5V buses. Please see the attache files.
What can be the reason for such spikes? Main big filter cap? It is CapXon 470uF/420V and its value is also OK.
I want to restore one old PSU. I found the main reason to not working. It was small cap (100uF/25V) on the Vdc bus going to the PWM controller. I replaced the cap with 470uF/25V (don't have currently 100uF) and PSU now works, tested under load with old GPU (ATi HD5830) and Furmark software. The replaced cap doesn't have any external signs of malfunction, even with capacitance meter is value is OK. But with it Vdc bus is ~11V and adding a small value like 4.7uF put the bus right, where it should be ~15.5V.
What currently doesn't like is the spikes on 12V and 5V buses. Please see the attache files.
What can be the reason for such spikes? Main big filter cap? It is CapXon 470uF/420V and its value is also OK.
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