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Suntac 286 hangs a lot

H

Half-Saint

Experienced Member
Joined
Apr 21, 2004
Messages
322
Location
Ljubljana, Slovenia
I picked up this complete system from the dumpster. Something I do pretty regularly and most machines just work but this one is giving me grief. I cleaned everything up and installed a new battery thinking that would be it.

Jumper settings here:
http://stason.org/TULARC/pc/motherboards/U/UNIDENTIFIED-286-SUNTAC-286P.html#.Vd_7WPmqp49

Unfortunately, sometimes it won't POST at all, at other times it boots but hangs while loading DOS. When it successfully loads DOS, it hangs sooner or later. Sometimes it also hangs while in BIOS.

Here's the patient:


What I tried so far with no success:
- replaced the memory with 44C256-80N chips from a different 286 board
- disabled onboard IDE and used a dedicated IDE controller
- removed co-processor
- disabled onboard floppy controller
- turned parity off
- replaced power supply
- replaced video card

Anything else I can do before I bin it?

Cheers

P.S. I noticed memory chips on the motherboard have -80P at the end while the ones I used to replace them are -80N. What's the difference, if any?
 
A wild guess, and probably wont work, but perhaps faster ram? If something is marginal, perhaps the extra speed will help, alternatively cut the system speed down. Sound like something is out of whack, and a signal is not getting someplace in time.
 
Just something to check - I had a similar problem with a 286 motherboard and as odd as it sounds, it turned out it was with the keyboard DIN connector. The battery next to it had corroded the contacts creating a weak/intermittent connection with the keyboard and somehow this caused the computer to not want to boot sometimes. Replacing the DIN socket fixed that.

Are there any really good, thorough, RAM testers for 8088/286 machines?
 
FWIW, I've had several battery episodes like that and the proximity of the keyboard socket has come into play on more than one occasion.

CheckIt v3.0 is excellent for RAM and will run on anything.
 
Just a quick update. I replaced the DIN keyboard connector which indeed had some green stuff on it but the board works (or doesn't) exactly the same as before.
 
I had a 486 system that had similar problems. The pins on the BIOS chip had some weird white stuff growing on them. It appeared to be some kind of corrosion. I lightly filed the pins down to remove the white stuff, and I cleaned the contacts in the socket and that seemed to fix the issue.
 
Half-Saint said:
Just a quick update. I replaced the DIN keyboard connector which indeed had some green stuff on it but the board works (or doesn't) exactly the same as before.
Click to expand...
Once you see 'green stuff' on the board there's no telling where else nearby on the board it's gotten into. It can destroy copper traces so if you see it somewhere you can verify their (the traces) continuity with an ohm meter. If you find a bad one it's possible to bridge it with a piece of thin wire. It (the green corrosion) could also be in between the board's layers in which case there's nothing to be done to rectify this problem. So it's a kind of hit and miss problem.
 
Stone said:
Once you see 'green stuff' on the board there's no telling where else nearby on the board it's gotten into. It can destroy copper traces so if you see it somewhere you can verify their (the traces) continuity with an ohm meter. If you find a bad one it's possible to bridge it with a piece of thin wire. It (the green corrosion) could also be in between the board's layers in which case there's nothing to be done to rectify this problem. So it's a kind of hit and miss problem.
Click to expand...

I'm thinking must be something of the sorts because I just finished reseating all chips near and around the battery and the board hung itself as soon as I entered BIOS.

Thanks everybody for the input but I think I'll be scrapping the board. Can't afford to sink much more time into this as there are other project I need to finish. If BIOS is corrupt, nothing can be done. I'd have better odds at winning the lottery than finding a BIOS image this old.
 
I can see what appears to be about five broken traces to the right of the standoff just above R45. Is that what they are? If so, repairing them, even with a jumper wire, may help.
 
Half-Saint said:
I'm thinking must be something of the sorts because I just finished reseating all chips near and around the battery and the board hung itself as soon as I entered BIOS.

Thanks everybody for the input but I think I'll be scrapping the board. Can't afford to sink much more time into this as there are other project I need to finish. If BIOS is corrupt, nothing can be done. I'd have better odds at winning the lottery than finding a BIOS image this old.
Click to expand...

Rather than scrapping them, I find it better to put them in a box with other faulty boards.
You'll never know when you need a certain chip, OR have more time and feel like giving it another go.
 
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