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  #1  
Old 02-19-2017, 02:32 PM
n74846 n74846 is offline
 
Join Date: Sep 2015
Location: Boca Raton, FL BCT
Posts: 105
Default Trim Position Indicator

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?
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  #2  
Old 02-19-2017, 03:03 PM
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tomkk tomkk is offline
 
Join Date: Apr 2014
Location: Port Orange, Fl
Posts: 765
Default

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.
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RV-12 N121TK ELSA #120845; first flight 06/10/2015
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  #3  
Old 02-19-2017, 06:12 PM
n74846 n74846 is offline
 
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Location: Boca Raton, FL BCT
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So your connectors were still the culprit. That's where I'll start then.
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  #4  
Old 09-05-2018, 05:03 PM
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sglynn sglynn is offline
 
Join Date: Mar 2008
Location: Anacortes, WA
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Default 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
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  #5  
Old 09-05-2018, 07:09 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
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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.
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  #6  
Old 09-05-2018, 08:40 PM
JBPILOT JBPILOT is offline
 
Join Date: Nov 2007
Location: Jesup, Iowa
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Default 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.
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  #7  
Old 09-05-2018, 08:43 PM
n74846 n74846 is offline
 
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Location: Boca Raton, FL BCT
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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.
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  #8  
Old 09-06-2018, 06:27 AM
JBPILOT JBPILOT is offline
 
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Location: Jesup, Iowa
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Default 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.
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  #9  
Old 09-06-2018, 06:58 AM
John-G John-G is offline
 
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 519
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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,
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  #10  
Old 09-06-2018, 08:48 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,714
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Quote:
Originally Posted by John-G View Post
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.
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