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Help with non booting OPTi-localbus motherboard

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First post, by Vegge

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So I have this motherboard that I really would like to get working. This picture is from when I bought it. I have replaced the missing 7F244N.

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The motherboard has Opti localbus and I would really want to try my NOS et4000ax for that port.
This is how far I've gotten with it;
I have tried different sets of ram in both bank 0, bank 1 and in both.
I have tried 64k, 128k and no cache.
Checked traces with magnifying glass and when in doubt with dmm.
CPU gets warm, it goes veeeery slowly through the post (looking at postcard) and after 1m30s halts at code 00 13 and then starts beeping. 6 long beeps but low pitch and since thats not a known code I suspect it's really 6 short but slowed down a lot. I tested this by removing the RAM and sure enough after 1min30s I get 3 low pitch long beeps. That 6 beep code seems to be "8042 - gate A20 failure".
Different kbc makes no difference regarding error code but with one of the AMI ones I tried the error beeping comes right away instead of after 1m30s.
Replacing the 33mhz oscillator didn't do anything either (its socketed anyway so easy to try).

I don't really know where to go after this. I have had problems with wierd beeping on a S7 board before and that one hade problem with voltage to the cpu but this seems to be fine (reads 5v).So I really don't know. Any thoughts and ideas would be appreciated.

Reply 1 of 5, by Tiido

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That 74F244 socket next to the oscillator will definitely have to be filled, it is normally a clock distribution buffer and I'm surprised you get any results at all in this state.

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Reply 2 of 5, by treeman

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might be totally unrelated but when I was fixing a board that had a few bent pins in the cpu socket I was getting alot of different errors gate a20 error was one of them. Have a good look in the back of the board at the cpu socket solder joints make sure they all look healthy

Reply 3 of 5, by Vegge

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Tiido wrote:

That 74F244 socket next to the oscillator will definitely have to be filled, it is normally a clock distribution buffer and I'm surprised you get any results at all in this state.

The 74F244 got replaced before I even tried booting it. (as mentioned in the original post 😉 )

treeman wrote:

might be totally unrelated but when I was fixing a board that had a few bent pins in the cpu socket I was getting alot of different errors gate a20 error was one of them. Have a good look in the back of the board at the cpu socket solder joints make sure they all look healthy

I have reflowed all dubious joints and all joints for the CPU socket. I had forgotten that. I've had this motherboard for a couple of months and take it out now and then and poke at it and then put it away again to fiddle with other stuff.

I only got sound out of it yesterday. The pc-speaker I usually use when testing old boards had died without my knowledge. So when I noticed that another board I fixed also didn't have any sound I tried with another speaker and voila; sound. That's when I took this board out again.

Reply 4 of 5, by Vegge

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As I'm going through my dead motherboards I came across this one again. I put supersoft in this one and it's painfully slow. From power on it takes right under 4minutes to get an image on screen. And the actual tests take about 10 minutes until it freezes at cpu protected mode. But all tests until then passes.
I had to film it just because how slow it is. The beeps are the HI/low beeps of the supersoft. Beeps for "cannot initialize monitor" But image comes up anyway.
https://youtu.be/JDvRf43tqV4

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