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Micronics 386/25 Motherboard POSTS - But I Get No Video

gatewayrepairs1985

gatewayrepairs1985

Experienced Member
Joined
Dec 10, 2021
Messages
104
Location
South Of Boston, MA
Hi all,

I recently acquired one of my dream machines - a Gateway 2000 386 from 1991. I really want to get it working to put it on display. However, the motherboard is giving me some trouble. It is a 386/25 Micronics motherboard, and I originally thought it was dead since I got no video. However, when I put a POST card in the machine I noticed activity - and the board did in fact POST! I even heard two beeps from the PC speaker. However, I still am not getting any video and I'm stuck. I tried another ISA video card to no avail. I tried another monitor to no avail. I need some help from the friendly folks here!

Any help would be greatly appreciated, thanks! Here's a picture of my board I took. Let me know if you have any advice!
 

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bostonvintage1993 said:
Hi all,

I recently acquired one of my dream machines - a Gateway 2000 386 from 1991. I really want to get it working to put it on display. However, the motherboard is giving me some trouble. It is a 386/25 Micronics motherboard, and I originally thought it was dead since I got no video. However, when I put a POST card in the machine I noticed activity - and the board did in fact POST! I even heard two beeps from the PC speaker. However, I still am not getting any video and I'm stuck. I tried another ISA video card to no avail. I tried another monitor to no avail. I need some help from the friendly folks here!

Any help would be greatly appreciated, thanks! Here's a picture of my board I took. Let me know if you have any advice!
Click to expand...
Look for a switch on the motherboard (SW1/6).

stason.org

386/25 Motherboard Settings and Configuration

386/25 motherboard and socket layout, connections, user configurable settings, DRAM configuration, Jumper configuration, floppy drive configuration
stason.org stason.org
 
Thanks for the tip!

Just for the heck of it, I tried changing that switch from on to off. Nothing happened unfortunately.

If you have any other advice, please let me know!
 
Is there not more than one position for the switch? See if you can match your motherboard with one on the STASON.ORG site.
 
Agent Orange said:
Is there not more than one position for the switch? See if you can match your motherboard with one on the STASON.ORG site.
Click to expand...
Hi,

The schematic you provided is my exact motherboard, I’m pretty sure. As you can see in the photo, the switch is red and only has an on/off position for each S/W. Thanks for the advice though. I’m super confused as to why I can’t get any video!
 
bostonvintage1993 said:
Hi,

The schematic you provided is my exact motherboard, I’m pretty sure. As you can see in the photo, the switch is red and only has an on/off position for each S/W. Thanks for the advice though. I’m super confused as to why I can’t get any video!
Click to expand...
That switch is supposed to let you configure which type of monitor that you have; i.e, MDA, CGA, etc. You may need to try different switch position combos.
 
hmm, is one of those EPROMs really not protected by a sticker?
that seems risky if not definitely a problem.

you may have a corrupt "hi" image, and need a newly burned part to get a known good Bios.
 
Twospruces said:
hmm, is one of those EPROMs really not protected by a sticker?
that seems risky if not definitely a problem.

you may have a corrupt "hi" image, and need a newly burned part to get a known good Bios.
Click to expand...
Hi,

The sticker fell off! I found it at the bottom of the case when I first got the machine and opened it up. I happen to have this exact board in another Gateway machine, should I try switching the BIOS chips to see if that helps? Would a faulty "hi" BIOS chip cause the board to still POST but have no video?

Let me know, thanks so much!
 
I would definitely try swapping the pair of ROMs, together.
I think what could have happened is that some corruption in one of the EPROMs could have supported some POST, but maybe not be correct still.
Good luck.
 
Twospruces said:
I would definitely try swapping the pair of ROMs, together.
I think what could have happened is that some corruption in one of the EPROMs could have supported some POST, but maybe not be correct still.
Good luck.
Click to expand...
Thanks for the tip, I appreciate the advice!

I switched them out. The second pair I had were M11’s, while the pair on this motherboard were M10’s. I don’t know if that made a difference, but when I swapped them out I got a beep code. I believe it is 1-1-4. Then I put the old pair back in and the same thing happened. Not sure what happened there. I did a quick search for beep codes for this BIOS and found out that this should mean “BIOS ROM checksum in progress or failure”. Not sure where to go from here. Any other advice you can provide would be super helpful! Thanks!
 
If you have an eprom reader you could always try to get the images and take a look. Partial erasure is pretty easy to see in the bit patterns.
 
What about putting your BIOS chips from the board you are trying to revive, into the other board, which I think you said is in another machine, known good?
(I would disconnect the HDD from that system when you switch the ROMs just to be safe)

This would help you verify that both sets of BIOS chips are good.

Once in the working PC you can get a utility to read out your BIOS, and you could post them as well. But if both sets check out then at least you know that is not the issue.
 
Twospruces said:
What about putting your BIOS chips from the board you are trying to revive, into the other board, which I think you said is in another machine, known good?
(I would disconnect the HDD from that system when you switch the ROMs just to be safe)

This would help you verify that both sets of BIOS chips are good.

Once in the working PC you can get a utility to read out your BIOS, and you could post them as well. But if both sets check out then at least you know that is not the issue.
Click to expand...
Hi,

Thanks for the great suggestion! I did precisely what you asked and the BIOS chips do not seem to be the problem. My working machine posted just fine with both sets of BIOS chips. Now I wonder where I should go from here. Thanks again!
 
Twospruces said:
What about putting your BIOS chips from the board you are trying to revive, into the other board, which I think you said is in another machine, known good?
(I would disconnect the HDD from that system when you switch the ROMs just to be safe)

This would help you verify that both sets of BIOS chips are good.

Once in the working PC you can get a utility to read out your BIOS, and you could post them as well. But if both sets check out then at least you know that is not the issue.
Click to expand...
I put the M10 BIOS chips back in the board and I get some new beeps before the board POSTS. I put in my POST card and I when I get the beeps, the POST card shows "262C". The beeps are as follows - one medium beep, one short beep, one medium beep, one short beep. Then the machine resumes booting and POSTS. I can even use the reset button on the case to reboot the machine. I just get no video, argh! Do you have any other tips? Thanks.
 
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