anetanel wrote:

Hi, I'm new here so please be gentle :) […]
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Hi, I'm new here so please be gentle 😀

I found today a dusty old Packard Bell PB301 computer, (with a 386SX CPU and no additional RAM installed) that was dumped in an abandoned factory for ages.
I was able to boot it without problems, and even captured the 1st boot on video:
https://youtu.be/WR5r7PXDDVo

I fiddled a bit with the BIOS settings and rebooted couple of times successfully, but after a while when trying to save the settings and reboot, the machine froze and refused to boot any more.
When turning it on, the PSU starts and the keyboard blinks once. But the screen stays blank (in sleep mode), and there are no beeps from the speaker.
There is nothing connected except the monitor and the keyboard. No FDD or HDD. I tried without keyboard too, but no cigar.

Could it be that I somehow corrupted the BIOS?
Is there an option to clear the BIOS? I tried disconnecting the power outlet for about 30 minutes, but it didn't help.
I also couldn't find a "clear cmos" jumper on the motherboard.

Any help is appreciated.
Thanks.

Sometimes the clear CMOS function is uninstalled, but still on the board. Try to look near the CMOS RAM for a set of three soldered in holes with two of them connected side by side.

You can also remove the battery or DALLAS style RTC chip.

If the BIOS is corrupted you will need an EPROM burner to burn the BIOS back onto the board. These are unfortunately not cheap, and require a minimal understanding of electrical engineering to operate effectively.

The EEVBlog forum has a lot of people for this if nobody can help you here.

Couldn't find any hints for a reset jumper. Does EPROMs even have rest function?
The battery is soldered, so I'm hesitant to mess with it.
I ordered a bios flasher, just in case. But it will be weeks until it arrives.
And even then, I'm not sure where I could find the correct BIOS file.

Could anyone point me to an appropriate BIOS file?
I was not able to find one on google...

Are you sure the cmos battery hasent leaked, i bought a laptop once from ebay 386 Toshiba, after using for about 2hrs the battery leaked and the laptop never booted again, once i pulled it apart i saw it had leaked onto the motherboard. Also try cleaning it inside first, taking memory out and putting it back in etc.

More than 3 years later, and I decided to give this machine another shot.
I cleaned the board, replaced the PSU with a known good one, but still not able to get it to boot.
I got a POST card in the ISA slot and it says "FF 05", which from all I can gather is actually good?
The one thing I noticed is that the UMC chip is very hot and even a bit discolored. could it be a dead chip that is causing the board to halt?

this seems to be common with this model. I've seen lots of them on ebay that say "powered on once and now it's dead". Hope you figure it out.