First post, by mwiik
I inherited a faulty Socket A system recently. It didn't power on at all, no activity when pressing the power button or otherwise shorting the power pins. When shorting the PS_ON pin directly on the ATX connector on the backside of the board, the fans spun up, but they stopped as soon as I removed the screwdriver. Keeping the pins shorted kept the fans running, but it didn't post (obviously).
There were quite a few bulging caps, so I did a partial recap and replaced them. I replaced all the large caps around the CPU and ATX connector, and a few smaller ones elsewhere. After that, the board powered on and POSTed! Success! Or so I thought. I played around with it for an hour or so with several reboots. Then it just suddenly stopped working again in the exact same manner after a power cut. One thing I did during the power cut was to install a PCI NIC, although I have a feeling that wasn't the cause. The previous owner said that it powered on twice before suddenly dying.
So I replaced the rest of the 1000uF caps, which means I have replaced all 1000uF and up. No luck. Still completely dead. I have tried three different PSUs, all of which work fine on another machine.
This is my first attempt at reviving an old board, so I'm not really sure how to proceed from here. Any tips on what to check next would be very much appreciated. I'm guessing there's something going on with the power circuitry, but I'm not very familiar with the inner workings of the power on sequence. There is 3.5V across the power pins and 5V on the WOL header, so at least there's some standby voltage.
I'm hoping I can introduce my son to some retro gaming during the winter. 😀
Thanks in advance!