I have an M520 that had a bad solder joint on one end of the keyboard fuse. Likely it was never a good solder connection, but it probably worked until it was put in storage and years of dampness caused corrosion. The AT port itself also had cracked solder joints, but the fuse's connection was the real culprit.

Repo Man11 wrote on 2022-10-24, 14:00:

I have an M520 that had a bad solder joint on one end of the keyboard fuse. Likely it was never a good solder connection, but it probably worked until it was put in storage and years of dampness caused corrosion. The AT port itself also had cracked solder joints, but the fuse's connection was the real culprit.

Thanks!

To do:
1) solder joints
2) fuse joints

I have to look for the fuse 😀

Edit: Vcc goes under the connector, will have to desolder it. Ok, nice Necroware wave here.
I'll look out for bridges though 😀

Ok, I did a Necroware, i.e. I skipped the most obvious thing to realize it was the first thing to do. 😀

If you are in the chess world, "motherboard speaks for itself".

100% back to normal.
Forgot to take a picture, but it's just some copper wires and solder mask.

PCChips is a source for entertainment.
No idea how this could have happened. There was some grime underneath.

Nexxen wrote on 2022-10-24, 17:42:

No idea how this could have happened. There was some grime underneath.

Was there even a fuse in that trace? Looks like there was a short circuit and that trace literally turned into an electric heater, that soldermask looks cooked.

adalbert wrote on 2022-10-24, 19:51:

Nexxen wrote on 2022-10-24, 17:42:

No idea how this could have happened. There was some grime underneath.

Was there even a fuse in that trace? Looks like there was a short circuit and that trace literally turned into an electric heater, that soldermask looks cooked.

No fuse.
I thought about it and my best explanation is this,
some days ago I did some soldering, I had the case open because I removed the Voodoo 2 that was inside.
Some solder scrap actually got on the board and I thought I had cleaned it, probably some got stuck and may have caused some sort of "something". There's enough space as the pins have a round stop mark and can't go in more than a certain spot.
The something I guess is the same that happens when you have some metallic object that makes a trace burn. I had that with a hard drive and a pci card.
The copper trace wasn't thin at all, quite sturdy. The bottom of the AT connector showed signs of heat. I got freakin' lucky.

Can't go further down the guessing game.

Well, I also bought this motherboard secondhand, could have been to its knees before I gave it the last blow 😀