What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Trim Position Indicator

n74846

Well Known Member
My trim position indicator has been erratic and inaccurate for a while, and now the indicator just sits at the bottom of the scale. Trim operation is fine so power (White wires) are OK. Before I go trouble shooting, my understanding is that if the connection/wires are bad I would see a red X over the scale, which I do not. Any thoughts before I start taking things apart?
 
I had the exact same problem. My problem was caused by a bad connection in the trim motor connector back in the tail cone. I had that thing in and out several times before I finally got it fixed.
 
Trim Indicator Jumping

Steve
What finally fixed your trim indicator erratic problem. I have it to. I'm not sure if my wiring got screwed up or if the trim motor is damaged or if I merely need to clean the connectors. My indicator jumps from full left to full right rather than moving smoothly along its throw.

Can the wht/green, wht/orange, wht/blue wire be mapped to the wrong pin and cause this?

thanks
 
To sglynn,
I think that you are correct about wires being connected wrong.
Try switching the wht/green and wht/blue wires with each other.
 
Wire crimping - -

is the likely issue. I have done mine maybe 3 times in 9 years. Those tiny wires are hard to get perfect crimps. I went against the instructions and soldered mine this year. Works perfect now. Not suggesting, just what I did.
 
I finally gave up trying to track down the issue and fly without the indicator. I visually confirm take off position before each flight, then the rest is feel. At some point I will replace all components.
 
Steve- -

When mine failed last time, it did the same as yours. Indicator went to bottom. If it was working at some point, then you just need better connections at the connector(s). There is enough wire extra, I could cut mine 3 - 4 times and re-solder them if needed. Stop the problem. Make sure the wires have some free movement so they don't pull on the solder connection.
 
Steve -

Getting a good crimp on the tiny pins used for the trim motor's Molex connector can be problematic ... as a review of past VAF posts will reveal. Fortunately, I had tiny jaws for my crimping tool and have not yet had any issues to this point.

However, that said, should the wiring to that tiny connector ever show the slightest hint of trouble, I absolutely would NOT repair the offending pin(s) and reuse that tiny Molex connector. Instead, I would suggest considering converting to male and female pins used in the DB connectors. After crimping the new DB male/female connector pins in place, mate the pins and slide a piece of TIGHT fitting heat shrink tubing over the pins then shrink ... you will end up with a long lasting trouble free connection that can easily be taken apart later should the trim motor need repair. The heat shrink will shrink down tight around the pins and will prevent them from coming apart on their own. Food for thought.

Happy flying,
 
Steve -

Getting a good crimp on the tiny pins used for the trim motor's Molex connector can be problematic ... as a review of past VAF posts will reveal. Fortunately, I had tiny jaws for my crimping tool and have not yet had any issues to this point.

However, that said, should the wiring to that tiny connector ever show the slightest hint of trouble, I absolutely would NOT repair the offending pin(s) and reuse that tiny Molex connector. Instead, I would suggest considering converting to male and female pins used in the DB connectors. After crimping the new DB male/female connector pins in place, mate the pins and slide a piece of TIGHT fitting heat shrink tubing over the pins then shrink ... you will end up with a long lasting trouble free connection that can easily be taken apart later should the trim motor need repair. The heat shrink will shrink down tight around the pins and will prevent them from coming apart on their own. Food for thought.

Happy flying,

Another option is to upgrade to the new servo tray which has an integral mount for a DB9 d-sub connector. This then utilizes the same pins but has the added benefit of easily separating the connection if needed.
 
Trim wires

To sglynn,
I think that you are correct about wires being connected wrong.
Try switching the wht/green and wht/blue wires with each other.

Joe
Yes it appears from testing that ORANGE is the common currently coming from the ACM unit. And I think BLUE is suppose to be common. So I'm going to swap blue and orange and give it a try. I'll see the result. I hope miss placing these two wires didn't damage the trim servo motor. Replacing it is easy enough.

The other ideas on crimping and soldering are welcome, but I'm getting continuity, just not proper function.

PS, the pitch trim works so well, that I know there is hope.
 
The trim motor is a completely separate circuit than the indicator. So no matter how the indicator is wired, it will have no affect on motor operation.
According to Van's schematic:
WHT/ORG is ground.
WHT/BLU is 5 volts.
WHT/GRN is signal.
 
Steve -

Getting a good crimp on the tiny pins used for the trim motor's Molex connector can be problematic ... as a review of past VAF posts will reveal. Fortunately, I had tiny jaws for my crimping tool and have not yet had any issues to this point.

However, that said, should the wiring to that tiny connector ever show the slightest hint of trouble, I absolutely would NOT repair the offending pin(s) and reuse that tiny Molex connector. Instead, I would suggest considering converting to male and female pins used in the DB connectors. After crimping the new DB male/female connector pins in place, mate the pins and slide a piece of TIGHT fitting heat shrink tubing over the pins then shrink ... you will end up with a long lasting trouble free connection that can easily be taken apart later should the trim motor need repair. The heat shrink will shrink down tight around the pins and will prevent them from coming apart on their own. Food for thought.

Happy flying,

I believe the original white colored 5 pin Molex connector is no longer available in the market place.
 
aileron trim indicator

Fixed.

Turns out the erratic aileron trim indicator issue was a setup in SkyView. I discovered this only after completely dismantling my connectors and the trim motor, testing everything, and found everything wired 100% correct.

In SkyView SETUP under HARDWARE > EMS > Aileron there is a calibration for the trim motor. Imagine trim calibration under EMS. geeezzz. It doesn't even plug into the EMS. Anyway, this menu has you move trim all the way right, then all the way left and wallah, it works. Trim indicator now moves smoothly with changing aileron trim.

No onto fuel level calibration with capacitance plates. This should be fun.
 
Auto trim issue

Nope not fixed. Just did a longer test and auto trim is going to far left. When I release the AP the plane rolls left. It is not trimmed.

Next is talk to Dynon more.

Thanks.
 
Back
Top