APRS/Voice HT Interface: Cap Failure

The TinyTrak3 on the Wouxun adapter wasn’t working, showing a dim red Power LED to indicate it wasn’t getting enough juice. A bit of tracing showed my adapter board provided just over 5 V to the poor thing, not the nearly 9 V it should be getting, which led me to believe the transistor switching the supply had failed. A bit more tracing, however, revealed the true problem:

Failed electrolytic cap

Failed electrolytic cap

The schmutz on the black cap matches up with a crater in the rear of the (originally not so) brown cap.

The Little Box o’ SMD Caps revealed two nearly identical sets of 33 μF caps, one with a 6 V rating, the other with 16 V rating. Yup, when I added that cap in the hopes of reducing RFI troubles, I soldered the wrong one onto the PCB: it’s my fault!

The poor thing lasted for over six years with just under 9 V applied to it, so I can’t complain.

I removed the corpse and reassembled the box without the additional cap (and without the terminals contacting the back of the Wouxun, because reasons). If RFI turns out to be a problem, I’ll take another look at the situation.


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