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'Sound-check' for glitch causing power supply


Old 06-18-2004, 11:42 AM
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Default 'Sound-check' for glitch causing power supply

If you ever have a model that has a glitching problem and has caused a crash, or a 'lack of faith', I have a very simple and quick check for the power system, which can be the cause.
It involves using a speaker to 'listen' to the power line at the receiver buss for any bad connections, frayed wires, 'iffy' switches or battery packs.

Only 3 items are needed:
1- a good quality new servo plug and wire fitting your receiver
2- a good 6x9 speaker or 6-10" woofer (preferably 8 ohm)
3- some thin speaker wire

Solder the black and red power leads of the servo connector to the speaker using a few feet of speaker wire and insulate them with heat-shrink or tape. (polarity is not important but the quality of the joint is)

Now, with your model fully charged, pull all the servos plugs from the receiver and plug the speaker into a channel.

Now, turn on the switch and 'wiggle and jiggle' all the wires and tap on the batt, switch and receiver to hear a bad connection.
The speaker cone will draw in, (or out depending on polarity) and any bad connection will be heard as scratching in the speaker, worse broken connections will be a 'popping' of the cone in and out. If the connection is clean and unbroken, the cone will stay in/out, but no scratching noise will be heard.
If there is scratching noise, start at the battery and work your way to the receiver, slightly bending and pulling on wires and connections to find the source of noise. Gently bend and twist the battery pack, jiggle the switch at the 'on' position, and wiggle the connectors going into the receiver to find vibration problems that only appear when the engine is running.

Even a wire on the battery pack that is frayed thin, but not yet broken will be identified. It can pin-point dirty or corroded switches, connectors, broken wires pulled in a previous crash, or even a bad solder joint on the receiver buss.

Because it's a 'loaded' test where approximately an amp of current is pulled on the system, it's better than a continuity test which can miss a connection nearing failure and it may find a weak battery too.

Planes that sit for long periods between flights should have the connectors pulled/put together, and the switch flipped back/forth a few dozen times to clean any corrosion before the next flight.

Models that are in the weather (sea-planes, boats, off road cars and trucks), should have silicon or dielectric grease put in the switch and all the connectors to prevent corrosion. If this was skipped and corrosion is already there, replace the wire, connectors or switch.
Corrosion on the receiver pins can be easily scratched clean with an exacto after taking it apart.

Have fun!!! Good luck!!!
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