Re: #manual #manual

TrueBlue
 

On Sun, May 13, 2018 at 05:05 pm, Al Sines wrote:
I recall your advice in the manual that components rarely fail
Interesting that you should mention that! 

"Rarely" is not the same as "never."  Just yesterday I did some troubleshooting on a U3S that had died after about a year's service.  All the programmed functions were OK and my nearby receiver was picking up a weak, but correct, signal coming off the synth board, but that was all.  Transistor was getting warm, so I figured I was getting power and I looked at every connection on the board to see what  was bad and found nothing imperfect, but I reflowed the solder through all the connections at that end and those in the LPF  Still nothing.  So I hooked up the dummy load and discovered that the measured voltage was so chaotic the DMM couldn't even get a fix on a single digit of the readout.  Looked like it had to be a bad BS170...and it was.  I replaced the original no-name BS170 transistor with a Fairchild and the U3S was instantly back in business.  These Fairchilds seem to produce a measurably stronger output as well.

I'm not sure I've ever seen this happen before.  I assume it was just a casualty of too many thermal flux cycles. [shrug]

I'm happy to hear you're back in business!

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