A little help?

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A little help?

Postby Floopy » 2017-10-15 @ 02:35

So I know it looks a bit bad to just sign up and start asking questions but here I go...
I recently started changing the Ni-Cad battery on my motherboards. The way I've been doing this is using 1.2V rechargeable batteries (3x) in a battery holder and I have plugged into the external battery connector (setting the jumper along the way.
My issue is that one of my 486 motherboard doesn't retain the bios configuration at all anymore?
There is not jumpers to set anywhere on the board. I've managed to track down the specifications and the board layout.
http://th99.classic-computing.de/src/m/I-L/32196.htm
Anyone have a clue what I'm doing wrong?

I would really appreciate it. It's getting annoying to have to set the bios every time.

And hello to the community
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Re: A little help?

Postby TheMobRules » 2017-10-15 @ 02:45

Normally the external battery connector doesn't recharge your battery, so that could be your problem. You're better off using regular AA batteries when using that connector, in many cases 4.5V (3x) is enough, if that doesn't work you can try 6V (4x or 2xCR2032). I know that's more than the 3.6V of the original battery, but those voltages are not a problem when using the external bat. connector.
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Re: A little help?

Postby Floopy » 2017-10-15 @ 03:46

TheMobRules wrote:Normally the external battery connector doesn't recharge your battery, so that could be your problem. You're better off using regular AA batteries when using that connector, in many cases 4.5V (3x) is enough, if that doesn't work you can try 6V (4x or 2xCR2032). I know that's more than the 3.6V of the original battery, but those voltages are not a problem when using the external bat. connector.

I will try with AA none rechargeable, but let me clarify: I do know you can't recharge the battery through the connector, the reason I used rechargeables is because they give me 3.6V.
Also if there is no jumper it means that the motherboard automatically uses the external when there is one?
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Re: A little help?

Postby TheMobRules » 2017-10-15 @ 09:09

Floopy wrote:Also if there is no jumper it means that the motherboard automatically uses the external when there is one?

Yeah, sometimes putting a jumper accross the second and third pins of the ext. bat. connector tells the motherboard to use the built-in barrel. In order to use an external battery, you need to remove this jumper and plug the 4-pin header into the connector. Other times there's a separate jumper for that, or even just plugging the external battery overrides the barrel one.

Also, I believe the external battery connector has a diode between it and the RTC/CMOS chip, so that may be another reason why 3.6V doesn't work as expected when using that header, since there would be a voltage drop and the chip ends up getting less than 3V.
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Re: A little help?

Postby Floopy » 2017-10-15 @ 15:59

Okay I will try that, thank you very much.
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Re: A little help?

Postby Floopy » 2017-10-22 @ 02:34

So I tried what was previously mentioned, but I'm having no success at all. :angry:
Anyone have any idea??
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Re: A little help?

Postby TheMobRules » 2017-10-22 @ 03:09

Bummer... here's a few things that can help you troubleshoot the issue:

Do all the CMOS settings get cleared as soon as you turn off the machine, or is it just a matter of the clock getting out of sync?

Have you tried both 4.5V and 6V external batteries?

It may sound stupid, but have you checked that you connected the ext. bat. the right way? Meaning, the battery "+" to pin 1 and "-" to pin 4 of the connector.

If you are able to take a picture of the board, we may be able to find something that you could have missed...

As a last resort, I suppose you could get a new rechargeable barrel and solder it to the board (but with some wires to keep it far away in case it leaks).
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Re: A little help?

Postby Jade Falcon » 2017-10-22 @ 04:23

What about soldering the battery pack where the barrel battery goes?
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Re: A little help?

Postby Floopy » 2017-10-22 @ 23:57

Jade Falcon wrote:What about soldering the battery pack where the barrel battery goes?

Well as much as I would like to I'm afraid that the mother board will try to recharge the battery.
And I don't want leaking batteries everywhere because of wrong voltage, unless I'm wrong? am I?
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