So I recently picked up an Epson Equity III+ 286 from Marketplace, and I had the owner POST test it. I basically got it for the monitor it came with, an NEC Multisync II, in good working order.

I decided today I will live stream me opening up the machine to see what's inside (I hadn't previously) and...

(in case you're curious)
https://www.youtube.com/watch?v=aRCpee3g3NQ

... the computer did and does work, I used it for many hours and left it on overnight to do a burn test. Amazingly what I found inside was functional:

This exploded and burned. The pin header plastic is melted in a few spots

It gets worse:

It looks like it took a s**t on the motherboard as well (original location of expansion card):

Soot, soot everywhere!

The charred remains of the culprit:

So, I have two questions to the community - What do these even do (I understand they smooth out dirty current, essentially) and what could the value of the capacitors (uF) be? My plan is to clean this up and redo the traces, as well as replace the caps. Computer works perfectly in this state!