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From: Jim Yanik
Subject: Re: maximum reverse voltage allowed on electrolytic caps?
Date: Thu, 14 Nov 2002 16:22:13 +0000 (UTC)
Organization: Friends of Lummox
NNTP-Posting-Date: Thu, 14 Nov 2002 16:22:13 +0000 (UTC)
"Phil Allison" wrote in
> "Frank Bemelman" wrote in message
>> I always assumed that, let's say, a few 100mV reverse voltage
>> doesn't matter, but is this a correct assumption ?
> ** I once had a 300 watt / ch power amp delivered for repair. It
> like it was brand new but was in fact 15 years old and came it its
> original carton. The complaint was "blows fuse". On the variac it
> showed OK up to about 30% of normal AC voltage and it worked - then it
> started to draw high current and was egding itself up so I wound back
> the dial.
> Once opened the problem was soon traced to a 10,000 uF, 80
> filter electro installed in reverse polarity. Not a bodgy repair - as
> done in the factory.
> I simply re-installed it the right way around and then all
> tests were
> fine, even a long soak test.
> Some electros are tough.
> ..................... Phil
I've heard some interesting stories at TEK about poor build of some of
their scopes and other instruments. I've seen scopes that came from the
factory with trigger IC's installed 'upside down' or reversed,where the
trigger could not even work,yet an inspector 'signed off' on the work. That
inspector and a few others lost their jobs as a result. I've even seen an
instrument where a PCB had NO solder,components merely held in place by the
lead crimps from the automated insertion machine.It looked to have missed
the wave soldering step completely! And it had worked for years!
Jim Yanik,NRA member
remove X to contact me
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