I had a HP 3326 which had a power supply in foldback. All the modules are inaccessible unless you have a rather rare set of extenders anyway. The voltmeter method quickly led me to the board and a bench supply and meter again to the shorted cap. Very easy. Other times I've borrowed the FLIR camera from work, also taught the new EEs that trick as well. It is a true lifesaver on dense surface mount boards. I haven't tried the liquid crystal sheet but it seems like an interesting idea so long as everything is about the same height.
Peter On Mar 23, 2012, at 11:53 PM, [email protected] wrote: > 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 <[email protected]> > Sender: [email protected] > Date: Fri, 23 Mar 2012 21:07:45 > To: <[email protected]> > Reply-To: [email protected], > Discussion of precise time and frequency measurement > <[email protected]> > 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 > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
