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486 build with a problem

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First post, by Kouwes

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I building a 486 machine for DOS games only, and then only games that have gravis ultrasound support.
The mainboard is from soyo, with a 5x86 -133 cpu.
It has a 2.1GB connor harddisk with NO bad sectors and a tseng ET4000/W32P video card. I‘m not sure if I should swap with a 4MB S3 Virge.
The FDD was bad, I guess a disintegrated belt, so I replaced it with a working drive. The power supply is a brand new Athena 300W from ebay, works very well and has 2 FDD power connectors in case you want to use a CF/IDE drive.
Well the machine posts fine: 32MB RAM, drives found but then it complains with a keyboard error: no KB found.
I tried known working 5-pin DIN and PS2 keyboards: same error.
But if you look a the pictures, you‘ll notice the gap between the board KB connector and the case. Now, when I bridge this gap (I used a screwdriver) the keyboard is found!
Problem is, I need a solution to bridge this gap with something that doesn’t fall out at some point - and maybe causes a nice short on my board!
I could cram some aluminum foil in there, and secure it with some glue…
Any better ideas?

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Reply 1 of 7, by nuno14272

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Sounds like a grounding problem... The gap is to be like that. .

Just reflow the solder on the connctor.. if you have a multimeter check the pinout online and see if the two ground pins are ok.

1| 386DX40
2| P200mmx, Voodoo 1
3| PIII-450, Voodoo 3 3000

Reply 2 of 7, by Doornkaat

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The S3 Virge is an overall better DOS graphics chip than any Tseng ET4000 imho. I'd just swap it.
Concerning the keyboard connector gap: do you believe this is a mechanical problem or an electrical one?
Did you try putting a screw in with above the keyboard connector? It appears to be missing in one picture.
If you believe the problem to be electrical try connecting a wire between the contacts at the screw hole and the metal spring at the connector.

Reply 3 of 7, by Kouwes

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The screw is missing because the hole is off center. Seems the case wasn‘t made very accurately. When I got this board there were those plastic pins in it so it hasn’t been screwed to the case in it’s earlier life. At least not using the upper left hole.

Reply 5 of 7, by CoffeeOne

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Kouwes wrote on 2023-05-08, 07:52:

.....
But if you look a the pictures, you‘ll notice the gap between the board KB connector and the case. Now, when I bridge this gap (I used a screwdriver) the keyboard is found!
.....

I do not understand that. 😁

What do you bridge???
So the keyboard connector does not go in fully?
Maybe just get another case, which is less weird?

EDIT: When you run the board outside the case, everything is fine?

Reply 6 of 7, by Kouwes

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@coffeeone: I put a screwdriver between the connector on the board and the case. The connector from the keyboard goes in fully and with the screwdriver in place it works very well.

I’m going to check if it works with board out of the case after work. Getting a nice AT case isn’t so easy these days 🙂.

@Doornkaat: no, the board doesn’t move at all, it’s secured with 4 screws.

I seem to remember that I did test this board like a year ago but I’m not quite sure. Whatever, I’ll try the board out of the case.

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