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Stuck mic and dead intercom

erich weaver

Well Known Member
Towards the end of a 2 hour local flight in my -7A today a spontaneous stuck mic condition suddenly occurred. Weird, as I hadn’t even pushed the mic button since takeoff and departing the airport area and was not adjusting anything when it happened. My intercom went dead simultaneously and I lost the sideltone in my headphone. Tried cycling the power on the intercom and radio a couple times to no avail. Gave up, turned the radio off and landed without incident. The intercom remained inoperative even with the radio off.

Havent started troubleshooting yet and not sure what to think. Is it possible that an intercom problem can result in a stuck mic?

SL-40 radio, PS Engineering 1000 II intercom

Not relevant to the problem, but the SL40 actually displays a “Stuck Mic“ message when this happens. Who knew?

Any insights or advice appreciated.
Thanks

Erich
 
First place I’d check is the mic jack - those things are easily shorted, and can take a beating if mounted in a place where you can bump the headset cords getting in and out.
 
Found the culprit this morning. The copilot side stick has a single control on it, a PTT button. The cap containing that button fits over the top of the stick. I had failed to lock the cap in place to prevent it from rotating during the build, instead just relying on the friction against the rubber stick grip. The laziness finally caught up to me. The cap had rotated enough to twist and strain the two PTT wires inside and as a result one wire grounded out and resulted in the stuck mic condition. All back to normal and now I can sleep peacefully again.

Erich
 
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