The flying monkeys got me...

Helis and fixed wing

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Saturday, March 31, 2012

HDX 500se Gremlins

I have been chasing one gremlin after another on the HDX 500se heli. Grinding main gear teeth, unexplained brown outs, frying servos, a dead BEC, a failed gyro (the Algin GP750 gyro wires wore out... and I had to replace it with the Align GP790). Its original equipment is aging. Other than the gyro, Occam's razor has an answer.

The issue has been brown outs. In flight these were a nightmare as the heli would change to default pitch. I could not figure out what was wrong. I suspected the BEC... I think the BEC was actually fine, though I fried a bad replacement, and now have a new 5A BEC on it that works fine. Today, having installed the new BEC, the brown out issue continued. I decided the only thing I haven't looked at was the reciever and its satellite. I changed out the reciever and the problem resolved. I reinstalled the original reciever, without the satellite, and it was fine. I installed the satellite and it browned out. I installed another satellite and cable and it browned out. Ah, ha! The old AR6200 works fine, but its satellite port shorts out. I powered up with a fresh battery and she remained bound for 10 minutes. The brown outs were probably causing surges as this process burnt out two servos. It doesn't take much to fry these Hitec HS 81mg servos, which is probably why they were discontinued, so I am replacing them with the improved 82mgs.

This took longer than it should have and I went through more parts than I should have. Here's hoping I have killed all the gremlins.

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