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Tuesday, March 12, 2013

Zapping static gremlins

In discussing my recent travails with the electrical gremlins in my HDX500 on Helifreak, Slyster offered up the notion of static discharges being responsible. This makes sense and I had given it some thought the first time I dealt with this a couple of years ago. That's when I started spraying the tail tube with lube. Random electrical parts getting zapped, and often affecting the servos, for the most part this seemed in retrospect to solve the problem. But it still happened though rarely, and as I noted zapped a servo recently. Maybe routinely spraying the tube with silicone is not enough; others have describe sparks despite the lube.
 
So I decided to up the game. I don't want to spend $50 on two G-force static wicks. So I grounded the tail boom, which acts like a van de graaf generator, hence the static problem, to the motor block using descriptions others posted on the web. Now the boom is essentially grounded to the battery (truly grounding it directly to the battery would require another wire to the neg lead of the battery, but for all intents and purposes its grounded).
 
Here you can see the entire grounding run from the screw in the tail boom peeking out on the right to where it snakes under the gyro platform and out the forward side to a bolt, then over to the top bearing block, and then down to the motor block where it ends on the aft motor bolt.
 
The metal boom is painted blocking conduction, and the block on the tail is aluminum, which is conductive. I drilled a small hole in the boom and set a screw just into the metal (avoiding the belt inside). The copper wire is wound around the screw and a dot of solder secures it. The wire runs under the gyro platform.
 
and comes up the other side. The first segment ends here, where I sanded the frame (so it also grounds to the frame) and attached the wire, the screw set into the aluminum head block. If I had planned this better I might have run one wire with spots of insulation removed to expose the wire, but, meh. So I start another wire there and ran another segment under the top bearing block...
 

and down inside the frame to come out and end attached to a motor block bolt, grounding the tail to the motor.
 
 
Hopefully this will cage the gremlins and I won't have to revist the magicla electrical mystery tour with random electrical failures!
 
UPDATE (3/13/13): I realized that I had put the screw on the boom in a place where the belt has made its turn and is in danger of rubbing. Psylence on Helifreak also pointed this out, and it convinced me to move it, so today I moved the tap to the top and out of the way of the belt. Cut a steel servo screw very short.
 
 
 

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