NiCd battery replacement in vintage computers
jrr at flippers.com
Sat Feb 6 15:57:47 CST 2016
On 02/06/2016 1:29 PM, Paul Koning wrote:
>> On Feb 6, 2016, at 4:21 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
>> Today I discovered that I hadn't replaced the NiCd battery in time in my Amiga 3000. Pictures:
>> While I begin to figure out how I'd like to perform this repair, I'm curious about what others have decided to do in similar circumstances. Many options come to mind:
>> * Solder in the same kind of NiCd pack to keep things original.
> I haven't yet done this, but I have a device (Fluke 881AB voltmeter) with dead NiCd batteries, and when I get around to replacing them that's what I was thinking of. NiCd batteries are still available.
>> * Solder in a supercap instead.
> That has vastly less capacity, and a very different discharge curve (exponential vs. nearly flat). Depending on the circuit using it, that might work slightly (at 10% capacity, maybe) or not really at all.
>> * Reconfigure the circuit to use a non-rechargeable lithium coin cell in a holder instead. I don't think I've seen one of those leak before.
> It hasn't happened to me, but have heard of one case of a leaking Li primary cell. Not a coin cell, but a C-sized one: I remember a report of one leaking in an automatic parachute opener (AAD), wrecking the parachute. In fairness, that was one left in quite a number of years beyond its expiration date. (Before someone asks the obvious: the problem was found during a required inspection on the ground.)
If you are running batteries in your machines you need to watch out for
battery leakage! These are all alkaline batteries so the only way to
neutralize the leakage is to wash and scrub with a mild acid - white
vinegar mixed 50/50 with pure water works very well.
Next, depending on the RAM device, it may be possible to use a
Ferromagnetic device to replace these - they are good for over 100 years
5101, 6116, 6264, and others are available from several suppliers
(including me). I have no idea what CMOS RAM is used in the Amiga, but
something needs to be done to protect these machines from
self-destruction by battery suicide!
Currently I have not seen a replacement for CMOS RAM that use separate
DI and DO pins such as some users of 5101s, but I am trying to get this
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