From: STeve Andre' (andres_at_msu.edu)
Date: Tue Feb 06 2001 - 11:03:24 EST
I can understand your confusion (or aggravation) over stuff like this.
It *is* the case that the smaller power supply should not be used,
but it's also the case that everything these days has a safety-factor
built into it. *Usually*, you can use the smaller supply, but there
can be some costs with it.
First, I have seen laptops (not yet ThinkPads, so this may or may not
apply to them) where an insufficient amount of current going to the
charging circuit results in the battery not being properly charged. If
a supply is rated for 1.1amps and the unit is pulling say 1.6A, there
is likely to be a voltage drop which is going to effect the unit. I know
of an older Sony laptop whose owner used an older Sony supply
when the right one died, and he thought it was OK 'till he discovered
that the battery never charged right. Getting the right supply made
everything work again.
The other problem is that the lifespan of the littler supply may be
diminished. Everything inside is going to be hotter, and anything
like an electrolytic capacitor is going to die earlier, by drying out.
If the unit gets hot enough, some of the solid-state components
are going to go earlier, too.
So, I'd use the smaller supply while keeping a keen eye on it, and
look for another supply thats bigger. If I was worried about the heat
I think I'd get some heat sink compound (like a white grease; Radio
Shack has it in the US), and put it on top of some large flat piece of
metal and make a heat sink for it.
--STeve Andre'
At 02:11 AM 2/6/01 +0200, Dominique Pivard wrote:
>Here you see! This is exactly what I meant when I talked about
>contradictory statements on the question: for every scientifically
>argumented explanation (I happened to receive a private answer from a
>physicist that made much sense to me) that one shouldn't use an AC adapter
>with a lower wattage than what the device is rated for, there always seem
>to be someone for whom it empirically works ...
>
>So what may be the consequences for Bruce's 56W adapter and/or T20, if he
>continues to use them together? Perhaps it's like smoking on your health,
>you don't see the results until later on ...
>
>Thanks, Dominique
>
>On Mon, 05 Feb 2001 at 06:57 PM you, "Bruce Markowitz"
><scosgt_at_worldnet.att.net>, said:
>
> >Baloney! I'm using one right now!
> >With IBM, generally if the plug fits, the adaptor is OK
>
> >----- Original Message -----
> >From: Tom Franklin <tom_at_franklin.to>
> >To: <domi_at_kenavo.fi>
> >Cc: <THINKPAD_at_cs.utk.edu>
> >Sent: Monday, February 05, 2001 6:10 PM
> >Subject: Re: 56W vs. 72W A/C adapter
>
> >> Your statements below are correct. 72 watts of power is fine for any of
> >those machines, but you couldn't use the 56 watt model for the T2x. >
> >> BTW: What price did you find for the power supply?
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