Uncreative Labs

Joined: 28 Feb 2006 Posts: 127 Location: LI, NY

Hi All,

I've encountered a sudden problem with my 486SX-25 tonight. I was using the computer fine all day (trying out new CF->IDE set up). After I moved my files from my old hard drive to the CF card, I turned off the computer and unplugged it to remove the physical hard drive.

Ever since that power down, I no longer even get a POST screen on start up. The screen never engages and the computer beeps one long time followed by three fast beeps.

I reseated all the RAM (4 chips) to no change. I've even pulled out ever ISA card. When the video card gets removed the beeps change to match the code for a video RAM failure (which I guess would be expected). I tried an untested second video card and there were no beeps but there was also no video and the lights on the keyboard seemed to look as if it was in a boot loop of some sort.

Last thing I tried was just reseating the BIOS chip as well. I popped it out and back in and there was no change.

Here's the BIOS in question: AMI 486 bios za425480

From: http://www.bioscentral.com/beepcodes/amibeep.htm
The code means: "A fault has been detected in memory above 64KB"

Is that the RAM I've reseated or could that be some RAM chip on the mobo decided tonight was the day to die?

Any ideas would be greatly appreciated. Let me know if any more information is needed.

Thanks in advance.

Posted: Thu Sep 19, 2019 4:36 pm

Pull as much RAM out as you can. Swap sticks until you get one that's causing a problem or works.

Joined: 28 Feb 2006 Posts: 127 Location: LI, NY

Thanks. I kept trying more today. I grabbed the RAM out of my 286 which I knew worked and still didn't change anything.

I decided to keep cleaning the connectors with 91% rubbing alcohol and q-tips and it finally worked after a couple of tries! The computer isn't even that dirty inside, it's amazing how little can mess things up.

I must have knocked on of the 'iffy" connected RAM sticks when swapping hard drives (bank 0 is right below the hdd tray).

Interestingly enough, the same error beeps happened when my video card wasn't seated right after the RAM issue was resolved. (Which was different than the video card not plugged in and RAM not connected right...)

Anyway, I was able to boot up again. I went through and cleaned every connector as much as could as I put everything back in.

I'm glad this computer isn't dead yet. It was our family's first "real" computer from back in '92 as well as where I programmed almost all my Qbasic stuff up until late 2006 / early 2007. So it holds a bunch of sentimental value.

Thanks again!