From: Jim Yanik
Subject: Re: cheap IR camera?
Date: Thu, 19 Sep 2002 14:07:17 +0000 (UTC)
Organization: Friends of Lummox
NNTP-Posting-Date: Thu, 19 Sep 2002 14:07:17 +0000 (UTC)
"George Gonzalez" wrote in
> Lately I've been resuscitating a pallet-load of Tek 465 and 475
> Some have easy-to-find problems with the power supply-- dried up
> bad bridge rectifiers.
> Most of the rest have shorted tantalum capacitors from one of the
> power supplies (-8, -15, +5, +15) to ground. These are a bit
> difficult to find, as there are many caps sprinkled around the boards.
> The method I'm using now is to push a few amps into the shorted power
> bus with an external power supply, then feel around for warm or hot
> This isnt a very good method, as it's hard on the series decoupling
> chokes, wound with like #30 wire, they get a lot warmer than optimum.
> Also depending on the severity of the short, the capacitor can get
> anything from just barely warm, to finger-burning HOT.
> Are there any reasonably priced IR sensors, like a small CCD TV
> camera? Last one I saw was 1000's of $, but that was a couple decades
> Any hints appreciated,
The IR cameras you want are very expensive. You could buy a few *NEW* TEK
scopes for what a thermal IR camera goes for. I used to clip a resistor
across the supply's current sense resistor to double the trip point,putting
more current into the rail,using the same or close value of the sense R.
sometimes,the supply would regulate. I've even seen the B-E drop across
those plastic power series-pass xstrs increase,putting the supply into
And I've even seen the tantalums smoke or pop.Sometimes,you can see a tiny
pinhole in the dipped tantalums,I always changed those.
ISTR Texas Instruments developed an 'inexpensive' thermal vision camera for
firefighters,it was an uncooled design based on microminiature bolometer
arrays.Maybe you could try a Google search?
Jim Yanik,NRA member
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