First post, by obcbeatle
Hello ... while I wait for some jumper wire I just ordered ... I thought I’d start another project.
I have a power supply unit (PSU) that when I turn on the PSU power switch ... the PSU fan momentary spins (with no noise .. it spins so briefly) and then stops spinning. This is when the PSU is not connected to the motherboard (mobo). I removed the PSU case and blew air through the PSU to clean out the dust, etc and inspected. Nothing jumped out at me visually. So I used a paper clip on a black ground wire and the green wire and the fan spins normally. I then checked the voltages of all the pins on the ATX 20 pin connector that connects to the mobo. ... all pins were within voltage tolerances. I also checked the separate ATX 4 pin connector pins that are on this PSU ... and that I believe is normally connected to the mobo for the CPU or a graphics card. All voltags were within tolerances. There is no 4 pin ATX connection on this mobo ... an ASUS A7V333-X ... (or on the original graphics card ... an AGP card). So I’m not sure why that seperate 4 pin ATX connector was included on the PSU for this mobo ... unless that was just normal for PSU’s back in the day. When I connect the PSU to the mobo to put a load on it the PSU behaves exactly the same way as when not connected to the mobo (very brief fan spin when powered on ... then the fan stops). I added the some RAM, a FDD, a HDD, keyboard, etc to give the PSU more load ... and still the same behaivor. In fact ... the CPU fan mimics the PSU fan when I turn the PSU power switch on (very brief spin ... then stops). The mobo LED light glows (and remains on) when the PSU power is on. The PSU is original to this mobo ... and this PC used to work a few years go.
So I think there is a problem with the PSU. What would you do next to try to verify or isolate the PSU problem? Any tips or suggestions appreciated. Thank you.