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Old Feb 21, 2011, 11:46 AM
Suspended Account
Panorama City, CA
Joined Sep 2004
5,566 Posts
How to repair bad trim on SkyFly/Turnigy/iMAX 9X

9X 송신기의 trim이 자주 고장을 이르킵니다.

그 수리법을 설명했습니다. 영문이지만 해독해주시기 바랍니다.

9X transmitter is known for frequently malfunctioning trim. Trim is stuck and does not move to opposite direction.

Here is how I repaired bad trim. The tiny tactile push button switch is available from allelectronics.com, part No. PB-126, price $0.25

While unsoldering trim switch from pc board, one terminal came off without heating. I realized that the cause lies in bad soldering, not bad switch.

So I soldered the original switch back into its place and tested trim. It worked. One cause of trouble was bad soldering.

I finished elevator trim assembly and tested again. The trouble appeared again. This time, the rocker mechanism failed to depress one switch, the up trim switch. Rocker and switch assembly was misaligned. When I held trim assembly with hand after realignment and tested, it worked.
I then glued the rocker and trim switch pc board with CA while holding it in working position. When glue dried, trim was tested and it was working.

A conclusion was drawn. The trim assembly mechanism need improvement.
Instead of assembling separate rocker and switch board by screw, the entire trim assembly should be made integral part. The rocker and switch board should be glued together and tested before mounting assembly to TX.

Trim assembly is held by two screws to TX body and easily removable.
It consists of two parts - a small pc board with two push button switches soldered in both ends and a rocker switch handle. When trim handle is moved to one direction, one leg of rocker pushes one switch; when trim handle is moved to opposite direction, rocker pushes the other switch.
When rocker and switch pc board are not in perfect alignment, rocker leg fails to push the switch, a cause of frequent trim malfunction.

I don't know how other brands trim mechanism is built but I have had no such trouble with other brands. FlySky should study other designs.
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Last edited by John Kim; Apr 05, 2011 at 11:32 AM.
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Old Jan 19, 2014, 12:09 PM
barryh18's Avatar
United States, CO, Colorado Springs
Joined May 2007
2 Posts
Here's a picture and alternative solutions

On my oldest radio my elevator trim switch (down) quit working. As a result, since the (up) switch was working I ended up with max elevator trim which of course is un-flyable.

At the field I used the trim function in the LIMITS screen to compensate for the full up trim and was able to fly.

When I got home I took the back off the radio and discovered the switch PC board to be easy access. There are two momentary switches associated with each of the four stick trim buttons. They are very modular and soldered to the small PC board shown in the picture. Using an ohmmeter I determined that the down switch simply would not make contact anymore. I tried contact cleaner in the hope that it might get inside and fix the problem but to no avail.

What I did for now (and I consider this a permanent fix) was switch the pc board so that the bad switch ended up on the throttle stick and visa versa. After all I've never used the trim function next to the throttle stick.

Here some other thoughts about how to handle this particular problem:

I could have programmatically enabled the throttle trim switch(s) to trim the elevator by adding 4 lines to the aircraft setup. The problem with this is that I would have to do it for every airplane in the radio. Not too big of a deal BUT why bother?

Replace the failed switch. I have now purchased a few from the site listed in the original post.
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