286 CMOS error and VGA exploding caps! \ VOGONS

286 CMOS error and VGA exploding caps!

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First post, by Half-Saint

Posted on 2014-12-22, 10:14

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I picked up a 286-16 PC from the dumpster and wanted to test it. First thing I noticed was battery corrosion so I desoldered the battery and cleaned everything up as good as possible.

I connect everyhing, turn it on and BANG!, an explosion, sparks flying around and the smell of burnt electronics. Holy shit! After inspecting the motherboard and finding nothing wrong with it, I look at the video card. Turns out one of the yellow capacitors exploded. I'm not sure why or if it's repairable...

Anyway, I tried the mobo with a different video card and it gives me an "CMOS INOPERATIONAL SYSTEM HALTED" error. Is this because there's no battery? I found a similar thread from 2011 here but it didn't help.

Cheers

Reply 1 of 12, by ReeseRiverson

Posted on 2014-12-22, 13:50

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Usually the battery shouldn't prevent the system from actually booting. All it does is keep the settings saved, and the time/date current.

I wonder if the GPU exploding like that could have caused some damage, since I only can see shorted capacitors doing that.

Reply 2 of 12, by Half-Saint

Posted on 2014-12-22, 13:52

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Yeah, that's what I thought too... I hooked up an external battery pack and it didn't help.

Maybe it was just that capacitor that was bad... don't know...

Reply 3 of 12, by ReeseRiverson

Posted on 2014-12-22, 14:10

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Have you checked the power supply to ensure it's feeding stable voltages?

Reply 4 of 12, by carlostex

Posted on 2014-12-22, 15:41

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Looks more like a corrupt BIOS. Does the CMOS error happen immediately after turning the machine?

Reply 5 of 12, by smeezekitty

Posted on 2014-12-22, 18:06

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The "bang" was just a shorted tantalum cap. Not that uncommon.

I will bet the "CMOS INOPERATIONAL" message is either because of no battery or because of corrosion damage

Reply 6 of 12, by Half-Saint

Posted on 2014-12-22, 19:13

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carlostex wrote:
Looks more like a corrupt BIOS. Does the CMOS error happen immediately after turning the machine?

The first thing I see is 512K Trident blah blah... next screen "CMOS INOPERATIONAL..." 😀

Reply 7 of 12, by carlostex

Posted on 2014-12-22, 22:41

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Half-Saint wrote:

The first thing I see is 512K Trident blah blah... next screen "CMOS INOPERATIONAL..." 😀

Yep looks like board doesn't even POST. I'm not sure if 286 BIOS'es had a small 4k or 8k boot block, like 486's have. Looks like what you need is to burn a new BIOS into an EPROM. Or a pin compatible EEPROM for that matter, which IMHO make much more sense these days.

Reply 8 of 12, by Half-Saint

Posted on 2014-12-23, 09:31

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Hey I see that you're a Dream Theater fan 😁

Reply 9 of 12, by carlostex

Posted on 2014-12-23, 13:14

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Half-Saint wrote:
Hey I see that you're a Dream Theater fan 😁

Oh yess... 😎

Reply 10 of 12, by Half-Saint

Posted on 2015-02-03, 10:53

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UPDATE:
Desoldered the cap that exploded and it looks like the card works just fine without it.

I'm gonna sell the motherboard to somebody with more time to try and fix it. I think carlostex's solution would probably work.

Reply 11 of 12, by Robin4

Posted on 2015-02-03, 12:43

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Always check the power supply first before connection it working to the motherboard.. If the PSU fails. I wont kill other components..

Stupid thing is power the system on for sake, and hope that it actually would work.. You could have save you to much trouble here.

Half-Saint wrote:
UPDATE:
Desoldered the cap that exploded and it looks like the card works just fine without it.

I'm gonna sell the motherboard to somebody with more time to try and fix it. I think carlostex's solution would probably work.

I would replace that capicator if its possible, maybe its for stabilise the voltages on that card..

~ At least it can do black and white~

Reply 12 of 12, by Half-Saint

Posted on 2015-02-03, 15:32

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I use two power supplies that I know are good for testing components.

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