DECpc 425SE

dwight dkelvey at
Thu Dec 5 08:18:43 CST 2019

With the solder tabs you are not soldering directly to the case, you are soldering to the tab.
If you try to solder to the case, the electrolyte will evaporate causing excess pressure in the case. This will burst the seal. For a lithium coin cell this can mean a fire.
As was mentioned, the solder tabs are usually spot welded to the case. The heat is momentary and little pressure is created in the cell.
From: cctalk <cctalk-bounces at> on behalf of Adrian Graham via cctalk <cctalk at>
Sent: Wednesday, December 4, 2019 5:17 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at>
Subject: Re: DECpc 425SE

>> Many years ago I removed the soldered coin cell from the control board of the Compaq 7000 series and replaced it with a 2032 coin cell holder, worked nicely so I can’t see why it wouldn’t work in this DECivetti monstrosity.
> Well I suppose removing it means unsoldering the two tabs from the motherboard rather than unsoldering the tabs from the cell, so maybe I'll give that a go. Then I could work out what the battery is, get a suitable holder and solder that in.

Yep. I’d never try and fasten tabs to batteries, they’re flash welded rather than soldered. Someone on hackaday reckoned they had a procedure to do it but fitting holders instead is so much easier.

> It would, however, be much more useful if a manual turned up and I could just perform a system reset and get past the password that way!

I wish I could help. I only ever worked on those when they were new.

Adrian Graham
Owner of Binary Dinosaurs, the UK's biggest private home computer collection?
t: @binarydinosaurs    f:

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