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Suntac 80286 Mainboards

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Reply 120 of 150, by Predator99

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Deunan wrote:

As for you new mobo, I can see A LOT of corrosion near the ISA slots, the '245, keyboard socket and the RTC. There's no way data signals D0-D7 are still working on this thing.
Considering the 008 chip state as well I'd say this is parts donor board at this point. I mean, it coudl be repaired, but is it really worth rewiring half the PCB?

Hehe, I agree to your observation, but "never give up". I think its not as bad as it looks like. Its powering up reliably, Supersoft is alo running with lots of errors... 😲

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Reply 121 of 150, by MMaximus

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So... I'm having RAM issues while trying to set up another Suntac board. This particular board supports SIPP memory, but since I only have 256kb SIPP modules, I'm trying to make it work with 1Mb SIMM modules in SIMM holders inserted into the SIPP slots.

The DIP switches for memory are set correctly on the mobo and it reports the correct memory size (4Mb). It posts without problem, but when I run a memory test in Checkit, I get lots of errors. I removed the SIMM modules from their holders and put them into a 386 board to test, and Checkit doesn't find any error so I assume the SIMMS are ok.

On the Suntac mobo there are 3 jumpers next to the DIP sockets: RAS, CASL, and CASH. I'm thinking maybe they're set incorrectly and that's why Checkit is finding errors? I've tested the 256kb SIPP modules and the Checkit test runs ok - it only happens with the 1M SIMMs (which are all 9 chip modules).

Any ideas?

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Reply 123 of 150, by MMaximus

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I wasn't aware of the possibility until I stumbled upon this article - which I think was written by a vogons member.

It's true that the contact between the pins and the slots is less secure as there is more movement than when only using SIPPs in the SIPP slots, but I assume that as long as the motherboard sees all the RAM at POST, then this means that all pins are connected to the board...

Reply 127 of 150, by MMaximus

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Predator99 wrote:
OK tahnks! Dont seem to be that expensive. […]
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OK tahnks! Dont seem to be that expensive.

Testx linked here 😉
ISA XMS/EMS Memory Extension / Expansion cards: Now Running without Driver / Documentation :-)
I like it...

Thanks for the link - very handy software for older systems!

I've used it and it looks like CheckIt was right - there are errors when the installed RAM>1Mb. I initially thought it was a problem when using 1M SIPP modules as the 256k ones tested ok, but I've tried with 2Mb RAM in 18 511000 DRAM modules and it gives the same error. So 512k RAM tests OK, 1Mb RAM as well, but 2M = not good.

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Reply 128 of 150, by HanJammer

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My collection of Suntac motherboards... all working perfectly fine. I had to add a small bodge on the backside of one of them because there was some dammage caused by something sharp and one of the traces was broken...

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Last edited by HanJammer on 2019-06-25, 13:42. Edited 1 time in total.

For sale (2019.12.01 - new items!!!): 8088, 286 stuff | 386, 486 stuff | Socket 5-8 stuff | Old HDDs and 5.25" FDDs

Reply 129 of 150, by HanJammer

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Two more...

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For sale (2019.12.01 - new items!!!): 8088, 286 stuff | 386, 486 stuff | Socket 5-8 stuff | Old HDDs and 5.25" FDDs

Reply 130 of 150, by BSA Starfire

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Got this one on the way(sellers pics) also a 20 MHz chips NEAT board. Looking forward to next week when I get to play around with this one.

286 20MHz,1MB RAM,Trident 8900B 1MB, Conner CFA-170A.SB 1350B
386SX 33MHz,ULSI 387,4MB Ram,OAK OTI077 1MB. Seagate ST1144A, MS WSS audio
Amstrad PC 9486i, DX/2 66, 16 MB RAM, Cirrus SVGA,Win 95,SB 16
Cyrix MII 333,128MB,SiS 6326 H0 rev,ESS 1869,Win ME

Reply 132 of 150, by dorkbert

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Got this board a few months ago. Applied power and got no response; power supply fan spins, so there's no dead short on the board.
It didn't come with the processor, so there was a pretty good chance that it was dead to begin with. Have not done anything else with it since.

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Reply 133 of 150, by MMaximus

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Predator99 wrote:

Think we know the seller :-p
Suntac 80286 Mainboards

Indeed 😎

BSA Starfire - Good to hear these boards are going to a fellow Vogoner! Looking forward to reading about them here once you get them 😀

Reply 134 of 150, by Predator99

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dorkbert wrote:

Got this board a few months ago. Applied power and got no response; power supply fan spins, so there's no dead short on the board.
It didn't come with the processor, so there was a pretty good chance that it was dead to begin with. Have not done anything else with it since.

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Nice board, all ICs on socket and spare ROM-sockets. Did you connect a speaker and did you hear anything?

If not, buy a POST-card from China first.

I would also verify the location of the 2 ROMs - maybe ROM0 and ROM2 are not the correct sockets? And most important (difficult to see on your photo): Do they have the correct orientation? Is the notch on the socket on the same side as on the IC?

Reply 136 of 150, by Predator99

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dorkbert wrote:

yes, it looks like EPROMs are inserted backwards. I pulled them and they're reading all zeros. I'll need to see if any of the BIOS would work on this board.

Yes, then you have destroyed the ROMs after powering on. Any image uploaded in this thread should work.

Reply 137 of 150, by BSA Starfire

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MMaximus wrote:
Predator99 wrote:

Think we know the seller :-p
Suntac 80286 Mainboards

Indeed 😎

BSA Starfire - Good to hear these boards are going to a fellow Vogoner! Looking forward to reading about them here once you get them 😀

They both arrived yesterday(Thanks MMaximus), In the process of building the Chips NEAT 286-20 into a case at the moment, but have tested both boards on desk and working a treat 😀

286 20MHz,1MB RAM,Trident 8900B 1MB, Conner CFA-170A.SB 1350B
386SX 33MHz,ULSI 387,4MB Ram,OAK OTI077 1MB. Seagate ST1144A, MS WSS audio
Amstrad PC 9486i, DX/2 66, 16 MB RAM, Cirrus SVGA,Win 95,SB 16
Cyrix MII 333,128MB,SiS 6326 H0 rev,ESS 1869,Win ME

Reply 138 of 150, by dorkbert

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Predator99 wrote:
dorkbert wrote:

yes, it looks like EPROMs are inserted backwards. I pulled them and they're reading all zeros. I'll need to see if any of the BIOS would work on this board.

Yes, then you have destroyed the ROMs after powering on. Any image uploaded in this thread should work.

To be fair, it was probably blown when I got it. That said, I ordered some 27128s and dropped them in after programming them with Award 3.03 (no particular reason, just randomly selected one from many BIOSes posted to this thread) and got some activity on the diagnostic card... but still no video. The bad news is the new diag card has a few dead segments on the LED (do they even test these things before shipping them?) so I am getting some code that I am not sure if they're accurate.

edit: left the thing plugged in for half an hour and now I got video; CMOS is (as expected) dead, but otherwise it looks like it might just work...
Not sure why it didn't come up initially. Power supply issue maybe.

Reply 139 of 150, by HanJammer

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dorkbert wrote:

edit: left the thing plugged in for half an hour and now I got video; CMOS is (as expected) dead, but otherwise it looks like it might just work...
Not sure why it didn't come up initially. Power supply issue maybe.

This or caps... I had tantalum caps on 286 motherboards behave erratic like that and then they blowed right into my face...

For sale (2019.12.01 - new items!!!): 8088, 286 stuff | 386, 486 stuff | Socket 5-8 stuff | Old HDDs and 5.25" FDDs