Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

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Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-12 @ 00:52

I recently acquired a unique 386 motherboard. There is absolutely no documentation or model number (other than just 386SI Rev. A printed in one corner and "made in taiwan rev." near the ISA headers. Initially I had the triple beep (no/bad RAM) but eventually figured out bank 0 was in the back rather than the front. However upon adding the ISA VGA card (some sort of oak OTI037C chipset) with one jumper. With this board it doesn't like it and quickly does a very quick double beep and then 8 beeps meaning something about video init failure. This card works in other machines however. In my 386sx-16 with a flat CMOS battery, it's just blank on the first boot and a warm reboot jogs the BIOS or CMOS to display POST messages along with the "CMOS display type mismatch message. On my pentium MMX board that still has a good battery it also works. I even tried moving the one jumper around to no avail. Both of my flatscreen monitors that have VGA throw an unsupported format error. I do not undertand why this one board doesn't want to attempt a different display type. I can't do the saw away and solder on a battery hack on the dallas chip, it's cornered in by the BIOS and keyboard chips. What's a good way to force the VGA mode on this motherboard so I can at least get it to boot to a screen? I would rather avoid trying to modify the BIOS code unless I had to absolutely do so.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby Deksor » 2019-6-12 @ 06:04

Can you please send photos of the board itself just in case ? ^^
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby luckybob » 2019-6-12 @ 06:38

I'm like 10 for 10 on "unidentifiable" boards if memory serves, but I need a halfway decent pic of the board.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby jesolo » 2019-6-12 @ 07:53

There is possibly a jumper on the motherboard to select between mono & color but, as previously stated, a picture of the motherboard will greatly help.

You can also take a look here to see if you can identify your motherboard (look for something unique in terms of the layout of your board): https://arvutimuuseum.ee/th99/#1
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-12 @ 20:06

I've tried that site but to no avail. Here's a picture of the board. The only jumper which is by the power connector does nothing in my experience.

weirdboard.jpg
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby quicknick » 2019-6-12 @ 20:22

Wow, that's one of the best looking 386 boards that I've seen. Love it, so sparsely populated. Regarding your problem, I don't think I can contribute much. Just that you should de-solder the Dallas module before attempting any work on it, then put it back in a socket. I'd do that. Also, try with other VGA cards, if you have them available.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby root42 » 2019-6-12 @ 20:32

I think this is your board: https://stason.org/TULARC/pc/motherboar ... 0S-47.html

Jumper JP1 should be closed for color monitors.

FIRST-INTERNATIONAL-COMPUTER-INC-386-386-25-33-40S-47-1.jpg


EDIT: Did anyone ever back up TULARC? Would be horrible if stason.org goes down at some point in time. Also: Where did the guy get all the information from???
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby jesolo » 2019-6-12 @ 21:26

root42 wrote:EDIT: Did anyone ever back up TULARC? Would be horrible if stason.org goes down at some point in time. Also: Where did the guy get all the information from???

Total Hardware 99 is being mirrored on a couple of sites, including the one I linked to above. I'm pretty sure that by now this has been archived dozens of times on archive.org.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby jesolo » 2019-6-12 @ 21:33

wackoreese wrote:I've tried that site but to no avail. Here's a picture of the board. The only jumper which is by the power connector does nothing in my experience.

One suggestion I can offer is to replace the Dallas RTC module. I recently bought the DS12887A replacement on eBay for a 286 motherboard of mine or, you can go the dremel route.

Also, on very same said 286 motherboard, I experienced the same problem with my VGA card. I really struggled for it to make proper contact in that motherboard, despite working perfectly on other boards. Try perhaps another display card.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby luckybob » 2019-6-12 @ 21:58

jesolo wrote:One suggestion I can offer is to replace the Dallas RTC module. I recently bought the DS12887A replacement on eBay for a 286 motherboard of mine or, you can go the dremel route.


+1

Quite a few early boards get really fucky without a bios battery.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby Deksor » 2019-6-13 @ 00:33

Speaking of TH99, someday I might come with a better solution than it (or should I say an improved one), but I can't unveil it now as it's far from finished. I'll inform you if I ever get it finished.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby Anonymous Coward » 2019-6-13 @ 04:15

Convert the rest of TH99 to VOGONS wiki. I already converted some, but haven't had time to finish the job.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby Deksor » 2019-6-13 @ 06:52

I've seen that, but what I plan will be better (also be careful because there are some misinformation in this such as wrong names, wrong brand, wrong supported CPUs, etc)
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-14 @ 20:48

root42 wrote:I think this is your board: https://stason.org/TULARC/pc/motherboar ... 0S-47.html

Jumper JP1 should be closed for color monitors.

FIRST-INTERNATIONAL-COMPUTER-INC-386-386-25-33-40S-47-1.jpg


EDIT: Did anyone ever back up TULARC? Would be horrible if stason.org goes down at some point in time. Also: Where did the guy get all the information from???


This must be the motherboard since it looks the same and it has a symphony chipset. It does not matter what JP1 is set to though, still the 1 double + 8 beeps. POST diagnostic card also never does anything but display FF (BIOS doesnt write to the port?).
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby root42 » 2019-6-14 @ 21:01

wackoreese wrote:This must be the motherboard since it looks the same and it has a symphony chipset. It does not matter what JP1 is set to though, still the 1 double + 8 beeps. POST diagnostic card also never does anything but display FF (BIOS doesnt write to the port?).


According to this website I would place my bets still on the video adapter:

http://www.bioscentral.com/beepcodes/amibeep.htm

The two beeps confuse me. Did you try some other RAM?
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-14 @ 21:10

What I mean by "double beep" is two very quick back to back beeps like there is a very quick pause between the two, and then the spread out 8 beeps. I don't have any other 4 sticks of the same type, last I tried gave me the 3 beep missing memory error.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby dogchainx » 2019-6-14 @ 21:52

I thought for sure my old 386DX system was dead, but it was three dead VGA cards in a row!
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-14 @ 23:02

The card itself works fine in other boards. However I noticed on ones with bad/dead CMOS I had to warm reboot otherwise the display never woke and it wouldn't post and I'd usually get the display mismatch error. If I had an EPROM programmer I'd probably try and modify the bios to default to a VGA color mod.
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby root42 » 2019-6-15 @ 07:04

I have VGA cards that don't like to work in certain boards. I would test with a different card still. The beeps suggest a problem with the card. You did also test with different ISA slots, right?
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Re: Unidentifiable 386DX motherboard being picky with video (won't POST, 8 beeps)

Postby wackoreese » 2019-6-15 @ 14:37

I did test with multiple slots. I've got a trident 8900 coming in real soon so I'll try that once it arrives.
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