Servo Experts

Here's the place to chat about radios, transmitter, receivers, batteries, and everything related to your radio gear.

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Dane McGee
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Servo Experts

Post by Dane McGee »

What makes a servo "go bad" while setting on the shelf?
What part inside the servo "goes bad"?

Lemme explain: I've replaced several servos in planes that have been setting on the rack for 2 or more years that I knew were good the last time the plane was flown. Most will not move at all or they move in one direction only.
I think I can rule out physical damage on most cause the plane was not moved till I got it back out to charge the batt.....I did check for stripped gears.
No matter how or where it is installed: wing, throttle or elevator....no worky.
RH
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Post by RH »

Dane, those servos are mighty chapped off that you haven't flown them for 2 years. They are out to teach you a lesson you won't soon forget....
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Dane McGee
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Post by Dane McGee »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by RH</i>
<br />.................... They are out to teach you a lesson you won't soon forget....
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

.............they succeeded[:D]
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cshepherd
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Post by cshepherd »

no servo expert here, but is there any geartrain grease in the servos? If there is grease perhaps it hardened up?
Vapor
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Post by Vapor »

Take the servo apart and spray contact cleaner into the hole in the bottom of the pot and work the servo while doing.
sgilkey
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Post by sgilkey »

I've even had Rx go bad while sitting on the shelf- plane flies fine, next time out, first flight it's glitching. strange....but I'm with Rick, I'd suspect the pot. I've had servos that could be reconditioned by just manually moving the output arm full throw in both directions a bunch of times, to clean the oxidation (or whatever it is) off the pot wiper. In a bad case I've had to open up the pot and clean the wiper and carbon disc with a pencil eraser. I like Rick's idea of spray cleaner better. I don't even use servo gear grease any more, I got the impression that it's mostly there for noise reduction, not lubrication, so if/when I replace stripped gears I don't bother with it (in the case of plastic gears- metal i'd lube)
crash_out
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Post by crash_out »

Yeah, I'd have thought the pots either go out, or maybe the grease in there gets hard over time/non use. I've had some GWS servos with bad pots-they start doing weird things-not centering, jittering..sometiems they'd stop comepletely until you knocked them around a bit...
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Dane McGee
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Post by Dane McGee »

I disassembled a couple of servos that were giving me trouble. I did notice a small amount of corrosion or oxidation on the outside of the pot. I used spray contact cleaner and sprayed thru the hole in the top of the pot while working the mechanism by hand. Assembled and it worked great.

I don't know how or what caused the the corrosion but apparently it was enough to foul up the works. One servo would not center, or slow to center and buzzed all the time. After cleaning the pot it is rock solid and no buzzing.

Thanks for the help guys!
Lee Liddle
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Post by Lee Liddle »

The combat gods are happy with you again.
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Dane McGee
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Post by Dane McGee »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Lee Liddle</i>
<br />The combat gods are happy with you again.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

[:D][:D]
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