VOGONS


First post, by pshipkov

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Didn't find anything relevant online.
Asking here.

386 motherboard suddenly started refusing to enter into the BIOS screen.
Pauses after counting memory but before displaying the resources table.
Keyboard is alive - pressing CTRL ALD DEL soft-resets.
Holding onto a key produces keyboard buffer full sounds.
Tried changing EEPROMs.
Tried different EEPROM/BIOS from different motherboard.
Same symptoms all the time.

Really unfortunate because it is one of those very rare boards that can actually works with BL3 upgrade module. 😖

Any hints ?

retro bits and bytes

Reply 1 of 15, by weedeewee

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no hint, just a suggestion. Clear CMOS ?

Right to repair is fundamental. You own it, you're allowed to fix it.
How To Ask Questions The Smart Way
Do not ask Why !

Reply 3 of 15, by GigAHerZ

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Yeah, i would suggest to deliberately "mess something up" - disconnect FDD or HDD or something like that so that the bios would whine about it. And then check, is the keyboard properly registered on that alert? (It probably asks you to either continue or enter bios)

"640K ought to be enough for anybody." - And i intend to get every last bit out of it even after loading every damn driver!

Reply 5 of 15, by TheMobRules

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Can you provide more details about the motherboard? Does it use a Dallas RTC? A picture or two could be useful, especially around the area of the chip where CMOS settings are stored (i.e. 82C206).

From your first post I understand that it used to work and suddenly stopped behaving this way? I would try following the traces that come out of the BIOS chip and see if there's any breaks.

Reply 6 of 15, by pshipkov

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Here is a pic that i think is good enough.
The board is in pretty good condition.
Inspected traces - everything checks out.
It feels like component(s) are starting to act.

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retro bits and bytes

Reply 7 of 15, by TheMobRules

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The empty 24 pin socket below the keyboard controller seems to be where an RTC should go, probably one with an internal battery such as the Dallas 12887 as I don't see any barrel or external battery connector. Do you install something in that socket when using the board? I don't think it would work properly without an RTC, unless it's not a discrete chip but is integrated in one of the Symphony chips, not really familiar with those.

Also, have you tested continuity on the two thick traces between the top ISA slots? They look corroded.

Reply 8 of 15, by pshipkov

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yes, i plug in the empty socket a dallas module.
added the socket a while ago sine the original module was surface mounted.

you have a good point about the 2 corroded traces. i didnt check them since the no bios issue surfaced.
thanks for the reminder.

retro bits and bytes

Reply 9 of 15, by TheMobRules

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Regarding the Dallas RTC, I noticed some strange behavior when trying to use an Intel board when the battery is either flat or new: it just hangs when attempting to enter the BIOS, because the CMOS settings are in an unexpected/invalid state. But I can still boot off a floppy and run a program called GSETUP to initialize the CMOS with acceptable values. Not sure if these symptoms are similar to yours but it may be worth a try, there should be some thread about this on the forum.

Reply 10 of 15, by majestyk

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I had the same issue with my 486SC-P (same chipset):

How can I safely transplant a 160-pin QFP chip?

Depending on the temperature of the 82C362 sometimes the system wouldn´t start at all, someteimes I could not enter BIOS, sometimes I could but the first BIOS screen would freeze accompanied by all possible beep codes imaginable.

These FIC mainboards are very reliable and durable otherwise.

Reply 11 of 15, by pshipkov

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Ouch.
Is this the death of Symphony Haydn season or what ?
Saying this because 3 weeks ago another Symphony board went silent on me.
It was a weak mobo so i didn't feel anything but the one in question here actually works with BL3 IODATA module which is very rare.
Will check those traces tomorrow.
Slap a Peltier element on the big chip - noticed that it gets quite hot quick.
The Peltier will chill it for good.

retro bits and bytes

Reply 12 of 15, by majestyk

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The 82C461 gets quite hot during operation - this is normal behaviour, the 82C362 however stays very cool. Try freezing it with some good coolant spray before turning on the system.
The 82C362 is absolutely crucial for the system since it controls all the periphery! When it fails anything is possible.
Still hope there´s some other culprit in your case...