[mdlug] [Fwd: Re: bios battery]

Raymond McLaughlin driveray at ameritech.net
Tue Jan 16 20:12:23 EST 2007


Garry Stahl wrote:
> Wojtak, Greg wrote:
>> If you are just going to pitch it, what's the harm in attempting a fix?
>>
>> * Gets ready to draw his soldering gun at ten paces... *
>>
>>   
> 
> Depending on the availability and cost of the caps I'll give my wife a
> try at it.  She can handle a soldering gun.  Getting the bloody things
> is likely the issue.

I'm in the same boat with a machine I have (several actually). The main
one is the old MDLUG server, which died of bad caps *three week* after I
swapped in a different machine. (I'm thinking of writing a detailed
history of MDLUG's servers on the
<http://mdlug.org/contacts/serveradmin/> page.)

My local Radio Shack did'nt have the exact ones, but if they did they
would be in the $1-$2 each range. I'm sure there are electronics stores
around that have them. Right now I'm keeping an eye out to maybe salvage
some out of some other device.

It's generally not cost effective to pay a technician to fix these, but
the parts cost could be worth it if you have a bit of time and the
skill. The entertainment/satisfaction value are harder to calculate.

One word of warning, in case any one was unaware, with electrolytic
capacitor *POSITIVE AND NEGATIVE MATTER!* There might be silk screened
markings on the mother board, but don't count on it. Make a note of the
polarity of the old ones before you remove them.

Also, one question for anyone who might know: The caps I'm looking at
are marked 1500 mfd, 6.3V, 105 deg C. How much lee way do I have on any
of these?

OK, the temp is obviously a maximum not a minimum, I just included it
for completeness.

I'm pretty sure the voltage is more of a maximum rating than a rigid
spec, so a little higher should be OK, I think.

What about the capacitance? My understanding is that these capacitors
serve as "power smoothers" i.e. by holding a charge, at an applied
voltage (not likely to be exactly 6.3V), on a DC power circuit, they
compensate for microsecond dips in the supplied voltage as power usage
fluctuates among the components. If this is the case then you should be
able to get away with a little over capacitance, but not under.

No doubt an exact match if probably best, and these are probably not
that hard to find if you really look, so I'm just wondering.

Raymond Mclaughlin



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