As part of my ongoing Socket7 quest I got an Epox MVP3C board. I flashed the bios with one from www.steunebrink.info/k6plus.htm (thank you Jan Steunebrink!) and after installing an AMD K6-3+ it ran great for a while then I had a catastrophic kb that killed the CPU and some other stuff. To effect a repair I first replaced the (obviously dead) main FET on the buck converter with an FDB6670AL. There are plenty of better power FETs available these days, I just had one of these handy. The original FET went up in smoke but from other pictures I've seen it may have been a B40NE03L. I tweaked the resitor network on the feedback to lower the base voltage to 1.9v (instead of 2). This worked well with a few sacrificial CPUs then I risked another K6-3+ and it's working well again. I noticed that the inductor was getting quite warm. The controller chip is a US3033. I can't find a datasheet for this chip that is not behind a pile of javascript/paywall/general-dumpster-fire-modern-internet but it looks like the main inductor should be around 4uH. The hot inductor is 11 turns on a blue/green (what looks like a) T50 core. I wound a new inductor that is 9 turns on a red/green T68 core. This is around the same value but runs much cooler.

So in case anyone else is using one of these boards with newer K6 CPUs, learn from my mistake and upgrade your VRM. Mainly, replace Q11 with something newer/better. You can also check the temperatures of other components and make adjustments as needed.