First post, by radiounix
So I'm pretty sure the power supply in my Unisys 486 has failed. Within the span of a day, the machine went from instability in Windows, to locking up in DOS copying files or running a benchmark and sometimes failing to complete the boot, to not posting and not sending out a VGA signal. I've got it stripped down to just 1 hard disk, one stick of RAM, no cache, and had tried setting BIOS to defaults, disabling all onboard hardware and shadowing in BIOS. It was stable before and had passed memtest86 and Spinrite when I got it maybe two weeks ago. This is probably a power supply fault, right?
This machine is a weird, late PCI 486 DX2/66 with no 3.3v regulator onboard and a 1000UF 10v capacitor where I would expect the regulator. It has a third motherboard plug which supplies 3.3 volts, and the OEM power supply has a 14 amp(!) 3.3v rail. I saw posts where people were like, "you don't need the 3.3v" rail, but I think they had regulators onboard still.
I know I should probably just be recapping this, but I don't like the idea of me soldering and messing around on a circuit that will run live AC. What are my other options?