[time-nuts] Anyone familiar with SR-620 repair?

[lists at lazygranch.com]

Prior to emission or IR microscope technology, liquid crystals was how you found hotspots on ICs. I've done this with a goop that you dispense with a syringe. 

One trick to make this more sensitive is you bring a soldering iron close to the  liquid crystals. Not so close as to cause a change, but you get them closer to the phase change point. 

  
-----Original Message-----
From: Skip Withrow <skip.withrow at gmail.com>
Sender: time-nuts-bounces at febo.com
Date: Fri, 23 Mar 2012 21:07:45 
To: <time-nuts at febo.com>
Reply-To: swithrow at alum.mit.edu,
	Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: [time-nuts] Anyone familiar with SR-620 repair?

You don't need expensive test equipment to find this kind of problem.  What
I use is a sheet of liquid crystal film with a transition temperature just
slightly above your room temperature.  Just lay it on the circuit board and
you can find where the power is being dissipated (even if pretty small) by
watching the colors change.

I think Omega Engineering sells a 8.5" x 11" sheet for about $18 if memory
serves me.  I have used this trick many times and it works great to find
shorted (bypass) caps.  No disconnecting anything, no milliohm meters, no 4
or 5 digit voltmeters.

Regards,
Skip Withrow
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