V911 servo fix - RC Groups
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Jan 26, 2012, 08:53 AM
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V911 servo fix

Myself and a friend of mine had problems with servos sticking, so i'm sure that many others are/will have this problem.
My aileron servo was malfunctioning, while my friend had issues with the elev' servo.
The only way to restore normal servo movement was to either tap the servo casing or move the servo arm.
Within minutes, the servo would malfunction again, however.
The problem, like many cheap servos, boils down to the VR (variable resistor) slider not touching the carbon track within the servo at various points.
You cannot get to this VR unless you remove and desolder the 3 pins that are connected to the RX pcb. You also need to remove the 2 diagonal screws which hold the relevant servo to the pcb.

Once you have carefully desoldered the 3 pins you can then remove the servo gaining access to the VR.

Don't go using a huge automotive soldering iron for this job otherwise you're asking for trouble. The board is double sided too so be careful.

I know this heli' is inferior junk, but before binning it I thought I would try this and it worked.
My friend reports that His v911 servo is still working around 50 flights hence since the repair.
Servo retracted from pcb

Remove silver plate to gain access to VR

Press down on the springy part of the slider where I point the driver, and place a drop of Deoxit on the local area. Work the VR with the servo arm.

The opposite servo needed repair on my friends as can be seen.. The elev' servo removed from pcb.
The final image is the servo re-assembled.
I used the Deoxit faderlube since faders (as in mixer sliders, etc..) use carbon tracks like these VR's.

Cheap switch cleaner (Servisol) might be OK for this task, but I prefer Deoxit.
Deoxit can be found for around 20 ($30) for 4 x 2mL tubes. Although it's quite expensive, a little goes a long way.

Sent from my E10i using Tapatalk
Last edited by Username>; Jan 26, 2012 at 11:18 AM.
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May 14, 2012, 01:38 AM
Brosol's Avatar
Excellent servo repair tips.

I have the same problem with a V911 Rx after dozen flights. The aileron servo sticks and works again for a few minutes after I torque the servo arm. I'm debating to order replacement servos, new Rx or find switch cleaner source to attempt a repair.

Is it easy to remove the silver plate to gain access to VR?
May 14, 2012, 01:57 AM
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I completely forgot about this tutorial.
Is it easy to remove the Silver plate to gain access to the VR?
I can't remember a great deal to be honest, but I managed it with minimal effort, and also put it all back together.
I don't fly my v911 anymore, but my friend does, and He reports that His servo has worked great ever since.
Mine had a good few flights after this fix and also showed no sign of imminent failure.
He announced that the fixed servo has done in excess of 200 flights, so it's worth trying even if you make an Henry Halls of it.

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