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JSR03 failure

Started by thommy, May 23, 2014, 01:45:36 PM

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I have had a jsr03 working ok for about 6 months. I removed it from one build and placed into another. On powering up the rectifier started smoking , no lights on the regulator and now when using another rectifier the same thing is occurring. Polarity is connected the right way, but there was one stray strand of the -ve wire that may have touched momentarily the X1 (+ve) connection. This is the only thing I can think of, allowing unregulated approx. 9.5v DC onto the ground plane.

Now it's impossible to perform any measurements on the board as it keeps killing the rectifier diodes, so how can I diagnose which components have failed?

My electronics knowledge is still limited so please refer to component codes on the PCB e.g. T1 rather than "the transistor near the opamp" for example.



OK, you could have had a short circuit anywhere.

Start to check the transistors with diode test.

For the PNP's: 0.6V between base and emitter and base and collector. Should be 0.000 or more than 1 V.

For the D44: as abobve but switch polarity.

Check the LM317 with diode test. If you have a unmounted one you can see what you should get.

Are the LED's OK? Check with diode test. Should be lit, very weak but visible.

Opamp could be fried.

If you have reversed the incoming voltage normally DZ1 LED and T5 will say goodbye and sometimes the opamp.

The destruction will almost instantly in case you don't have any fuse or current limitation.
/Per-Anders Sjöström, owner of this forum

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