486 Board with external battery \ VOGONS

486 Board with external battery

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First post, by Kouwes

Posted on 2023-10-29, 14:24

Kouwes Offline

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I have this FIC 486-GIO-VT board without cmos battery so I figured I‘ll just grab an external 3 x AAA battery holder…
Turns out the board has a jumper for internal/external battery. Too bad you can‘t set the jumper to 1-2 because there‘s a cap blocking it.
Any ideas how to bridge pin 1-2 without crazy bending and soldering?
It‘s J3, jumper is set to Internal Battery 2-3.
Looks like the original coin cell holder was removed at some point, there‘s some solder tin left in the holes.
I wonder why. But I do have a CR2032 holder from some scrap board which I could use.

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Reply 1 of 9, by DrSwizz

Posted on 2023-10-29, 15:57

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Remove the plastic "case" on the jumper and bend the cap slightly and queeze in the jumper in there?

Reply 2 of 9, by majestyk

Posted on 2023-10-29, 16:03

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Just bend the two tantalum capactors to the left - gently.
I have a couple of GIO-VTs and there was always enough space for the jumper.

Reply 3 of 9, by analog_programmer

Posted on 2023-10-29, 19:18

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Hmmm, isn't J1 4-pin header for 4.5V external battery connection?

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Reply 4 of 9, by pan069

Posted on 2023-10-29, 19:47

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analog_programmer wrote on 2023-10-29, 19:18:

Hmmm, isn't J1 4-pin header for 4.5V external battery connection?

Yes, but to enable external battery he need to enable it on the board with JP3, the 3 pin jumper block next to it.

Reply 5 of 9, by analog_programmer

Posted on 2023-10-29, 19:52

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pan069 wrote on 2023-10-29, 19:47:

Yes, but to enable external battery he need to enable it on the board with JP3, the 3 pin jumper block next to it.

JP3 or J3? I can't see JP3. And what is the problem if (probably) J3 has to be removed?

Reply 6 of 9, by Kouwes

Posted on 2023-10-29, 21:07

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It‘s J3, a 3 pin header currently set to pin 2-3. You can clearly that there is no room for a jumper between the tantalum cap and pin 1. Bending the cap is no option, it won‘t move at all because the legs are too short.
I‘ll try stripping a jumper .

Reply 7 of 9, by analog_programmer

Posted on 2023-10-29, 21:13

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Kouwes wrote on 2023-10-29, 21:07:

It‘s J3, a 3 pin header currently set to pin 2-3. You can clearly that there is no room for a jumper between the tantalum cap and pin 1. Bending the cap is no option, it won‘t move at all because the legs are too short.
I‘ll try stripping a jumper .

I didn't saw the third pin on J3, sorry. Just bend slightly the two tantalum caps to the side so the jumper will fit or bend the pins 1 and 2 of J3.

But I think there's a chance that position 1-2 on J3 is just a "holder" for the jumper and pins 2 and 3 on J3 are in parallel with pins 2 an 3 on the J1. Check the schematic with multimeter in continuation mode.

Reply 8 of 9, by majestyk

Posted on 2023-10-30, 08:14

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Kouwes wrote on 2023-10-29, 21:07:

Bending the cap is no option, it won‘t move at all because the legs are too short.

This would be true for larger cylindric electrolytics. Tantalums become narrower at the bottom end, so they can be bent easily. I have done that hundreds of times.

Reply 9 of 9, by Kouwes

Posted on 2023-10-30, 09:07

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Yes you are right. I was too cautious I guess because that wouldn’t be the first cap I break off a board. The jumper now sits on 1-2 so all good!
Thanks for your input.
Now I can finish this build: 486DX2-66, 16MB FPM, Tseng ET4000 and an AWE32.
I might go and look for a nice VLB card though.

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