Schule04 wrote on 2021-04-22, 21:39:

is it really necessary to seal the traces? Isn't tinning them not enough?

tinning them makes'm thicker and gives'm a coating so the copper doesn't corrode.
sealing the traces makes'm not susceptible to short circuits due to loose screws . 😀

I would be very careful with sealing. You could regret it, when a second repair is necessary or if components have to be replaced in the future.

It also depends on how you repair the trace.
If you scrape back some trace that's oxidized from a varta battery leak... and you attach a copper wire along the trace line, you can tin that entire section, but sealing it sure is cleaner and less likely to short.

But yeah, if you tin the entire area, I suppose you don't NEED to seal it. With traces, I'd rather seal them up though. I don't see re-repairing a trace line as much as component replacement. I wouldn't seal component solder points.

Super Mario wrote on 2021-04-22, 21:01:

If I don't get the motherboard working, can I connect the hard disk to any 486 and access the files, run programs etc on DOS and windows or should I use the exact same motherboard / components?

Main reason why I try to get the PC working is to copy stuff I made in the 90's to my new PC, but I would also like to check windows and run the programs I used back then.

if it's a typical IDE drive and you have another computer that can read it, say an old win 98 or win xp machine with IDE, the you could mount it as a 2nd drive and copy all the files over somewhere safe

majestyk wrote on 2021-04-23, 05:52:

I would be very careful with sealing. You could regret it, when a second repair is necessary or if components have to be replaced in the future.

A bit of acetone on a cotton swab removes the nail polish easily, you can wipe the residue off with IPA..

Why is there a sticker on my cpu 😁

Super Mario wrote on 2021-04-23, 10:54:

Why is there a sticker on my cpu 😁

It’s where I hid the combination to locker #3 at the Newark Greyhound station. 😉

What temperature and how long should I bake the motherboard in the oven after cleaning it?

You shouldn't really need to - as long as you get rid of most of the vinegar, then rinsing it off with IPA should mean that the alchohol will evaporate within a few minutes (as long as it isn't dripping wet).

You could use a hair drier if you wanted to speed up the drying, but I don't think it's really necessary.

The keyboard started working after I soldered L3 and L4 with wires. I got the same errors as before, but not the keyboard error. I pressed F1 to enter setup, but after that the keyboard stopped working. I restarted the computer and got an error "parity error, system halted". I restarted the PC again and now there is no picture on the monitor. The power and turbo lights are off now too.

Tough to say whether that's a ram issue or just more signs that the contacts aren't clean or the board corrosion needs further attention

ThisOldTech wrote on 2021-04-23, 17:56:

Tough to say whether that's a ram issue or just more signs that the contacts aren't clean or the board corrosion needs further attention

I have three sticks, but I'm not sure which way they should be installed. They seem to go in both ways.

ThisOldTech wrote on 2021-04-23, 17:56:

Tough to say whether that's a ram issue or just more signs that the contacts aren't clean or the board corrosion needs further attention

I'm going to go with, the board corrosion needs further attention. 😀

Super Mario wrote on 2021-04-23, 18:04:

ThisOldTech wrote on 2021-04-23, 17:56:

Tough to say whether that's a ram issue or just more signs that the contacts aren't clean or the board corrosion needs further attention

I have three sticks, but I'm not sure which way they should be installed. They seem to go in both ways.

The RAM is almost certainly not the problem - you've still got corrosion on your board and either failed components from the battery leak, or at least one (probably more) traces have been eaten through.

I don't know of any kind of PC memory module that can be inserted fully when flipped 180 degrees. Both 30pin and 72pin modules that 386/486 boards use have notches on one end only, so that the retention mechanism of the socket can only be engaged when the module is inserted correctly.

I removed the sound card and one of the memory sticks that looked different and now it works again. I get a message on the startup that I must enter setup. Setup menu, keyboard and mouse all work normally but it looks like that my computer doesn't recognize the hard disk. There's many different options to choose from in the hard disk menu. Automatic detection didn't find it either. The jumper is on the master position. Anyone know how to proceed?

Super Mario wrote on 2021-04-23, 19:21:

There's many different options to choose from in the hard disk menu. Automatic detection didn't find it either. The jumper is on the master position. Anyone know how to proceed?

Just going to ask if you've got the hard drive ribbon in the proper position pin 1 on the end where the red line is and the hdd at the end of the two connector hdd cable.
Weird to suggest but sometimes trying cable select (CS) can work on weird drives... is the hard drive spinning up at all? If it's an older drive are there other jumper options to look up or just the CS/SLAVE/Master?

If everything's connected properly and the drive is spinning up, only other option is to try a different drive and try that drive on a different computer... or check your I/O card (if it's not built into the board) to see if the IRQ is set to the proper one for primary IDE...

ThisOldTech wrote on 2021-04-23, 20:26:

Just going to ask if you've got the hard drive ribbon in the proper position pin 1 on the end where the red line is and the hdd at the end of the two connector hdd cable.
Weird to suggest but sometimes trying cable select (CS) can work on weird drives... is the hard drive spinning up at all? If it's an older drive are there other jumper options to look up or just the CS/SLAVE/Master?

If everything's connected properly and the drive is spinning up, only other option is to try a different drive and try that drive on a different computer... or check your I/O card (if it's not built into the board) to see if the IRQ is set to the proper one for primary IDE...

I added images where you can see how the cable is connected. The hard disk spins normally. Only cs, slave and master. Switching to cs didn't work either.

Mouse is also connected to the same card as the hard disk and the mouse works, so the card should be ok?

How do I check the IRQ?

Update. I ran the "detect C" utility in bios again and this time it gave me the properties seen in the image below. I accepted them and after reboot I got an error message "HDD controller failure.

The values detected by the BIOS are correct, as they are the same as those printed on the hard drive. If at this point you are getting that disk controller failure, either the drive or the controller is faulty IMO. One of them is flaky.

I removed the jumper from the hard disk and now both dos and windows work 🙂

Only problem is that the mouse didn't work in dos or windows. If I try to run a program that requires mouse in dos, I get a message "did not find a mouse driver". So I guess I have to install the mouse driver next.