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computers / comp.sys.ibm.ps2.hardware / Re: CD6 and CD4

CD6 External Battery jumper on 4755

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From: ohland@charter.net (Louis Ohland)
Newsgroups: comp.sys.ibm.ps2.hardware
Subject: CD6 External Battery jumper on 4755
Date: Wed, 19 Oct 2022 08:22:28 -0500
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by: Louis Ohland - Wed, 19 Oct 2022 13:22 UTC

Re: CD6 and CD4

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From: slavotinek@gmail.com (Tomas Slavotinek)
Newsgroups: comp.sys.ibm.ps2.hardware
Subject: Re: CD6 and CD4
Date: Wed, 19 Oct 2022 22:12:44 +0200
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by: Tomas Slavotinek - Wed, 19 Oct 2022 20:12 UTC

On 19.10.2022 15:22, Louis Ohland wrote:
> "CD6 External Battery Currently ignored; but a jumper MUST be installed."
>
> Wonder if this means that CD6 is where the external battery is
> connected. Y'know, positive and negative leads?

Yep, pretty sure that's where it goes.

And regarding the CD4 jumper... Looks like the negative terminal of BT1
isn't tied directly to the internal ground plane as it normally would.
Instead it goes to the CD4 header *AND* the MCA edge connector. Without
the CD4 jumper installed the battery is probably grounded only through
the MCA connector/planar ground plane. So, if you remove the adapter
from the machine, the ground connection is severed and the contents of
the RAM destroyed. CD4 grounds the battery locally, disabling the feature.

That's my SWAG anyway...

Subject	Author
CD6 External Battery jumper on 4755	Louis Ohland
Re: CD6 and CD4	Tomas Slavotinek