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Rescuing an old 386/486 motherboard – Pa ...

Rescuing an old 386/486 motherboard – Part 1 (2021/12/13)

Dec 13, 2021

This “random” machine has been in my storage area for a long time, I wasn’t even sure if it worked at all. I only knew that it was a 286 or 386 based in the rear I/O and a lonely 5 ¼ drive. Already removed the drive in the picture, but can see a bit of it, I still have to test that drive.

I was afraid of the motherboard being damaged by the battery, so that was my first objective. And as you will see, I was just in time, a bit more of time and the corrosion could have caused some severe damage. Also I was able to confirm that the machine is a 386, with an AMD Am386 DX40 installed.

Since I´m learning to do this kind of restorarions and the corrosion was not so bad, I wanted to test it to see if it was alive before attempting to remove the battery. Luckily it powered on without problems, but a problem appeared as soon as I entered the BIOS: you were unable to set up values like date and time, when you tried to change a value the numbers jumped at random.

So, knowing that the board is alive, time to remove the battery!

Since I still lack some tools, I went for the “manual” route, and gently bended a bit the battery supports until they ended breaking off. With that removed, I was able to survey properly the corrosion. The good news was that it was not so extended, so was I washed the area with a generous dose of white vinegar and Q-tips. After that, time for another generous dose, this time of IPA, which I was able to get in this handy presentation thanks to MAC Lubricantes. You can see the result!

After leaving the board to dry for a day just in case, I went to try it again and… it works perfectly now! The BIOS behaves at it should, allowing a proper configuration even if, of course, is not going to save the configuration after a shutdown. In the future I will install a 2032 battery holder.

So time to connect a 3 ½ drive to do some testing with Check-it!

The IDE controller worked just as intended and was able to run several test with Check-it, benchmarks and some tests. Having 8 Mb of good RAM is great! All the test that I run in this first try worked perfectly, the board seems to be stable and ended running several hours running RAM test without problems. The Cirrus Logic (CL-GD5401-42QC-B) VGA ISA card that came with the machine also works fine, so another win for the retro team!

The computer also has a hard drive, a Quantum ELS170A, that I tested out separately just in case. It appears to be in working order and I already did a copy of its contents just in case. Once of the next things to do is going to be to try out this drive with the 386 to see how it goes. By the contents, looks like this machine was used in a office or something similar.

Additionally I think I will take the opportunity to test out more RAM sticks and a couple of ISA video cards that I have, so stay tune for the next part! Buymeacoffee is droping Paypal as an option for their platform, but is Payoner is not for you, you can still ask me for my paypal!

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