Espritmodel.com Telemetry Radio
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Old Nov 06, 2013, 12:12 PM
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advice needed

Any one able to help? My DH6i transmitter suddenly went funny today. It simply wont work on elevator control. I have checked all connections and cleaned them up, checked the potentiometer, etc but nothing. The best I can get is to make the elevator servo jitter.
When placed in "monitor" mode, the screen clearly shows that the servo is not working but all other controls show normal. I have tried various servos but the same result, dead as a doornail on elevator.

Any ideas as its the only Transmitter I own. I suppose I can count myself lucky in that it happened on switch on and not during a flight this morning! Thanks,

Colin,
South Africa.
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Old Nov 06, 2013, 01:21 PM
Splat
United States, FL, Palm Harbor
Joined Jul 2007
399 Posts
Have you tried a different receiver to be sure that the problem is the TX? Also, if you tested the potentiometer on the elevator to see that the voltage at the center pin varies with stick position, then I would double check the wires connecting the Potentiometer to the board.
If the screen on the transmitter does not show activity when the control is moved it almost has to be a wiring issue. also check for solder shorts. Especially if you have been inside the TX doing mods, etc.
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Old Nov 07, 2013, 12:07 AM
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Quote:
Originally Posted by PLC77 View Post
Have you tried a different receiver to be sure that the problem is the TX? Also, if you tested the potentiometer on the elevator to see that the voltage at the center pin varies with stick position, then I would double check the wires connecting the Potentiometer to the board.
If the screen on the transmitter does not show activity when the control is moved it almost has to be a wiring issue. also check for solder shorts. Especially if you have been inside the TX doing mods, etc.
Thanks for the advice as above. It all sounds good.
Yes I have tried a different receiver but with the same result. First thing today I managed to carefully pry the plugs from the sticks out of the board sockets and did some swopping around.

I found that the problem followed the same stick assembly no matter whether it was plugged into the elevator or throttle plug on the board. However, when I tested the wiring and the individual potentiometers on the board, they all gave the same readings !!!! Odd... I am now looking for another old stick assembly so as to do a swop and see if that can solve the mystery. Not easy when the nearest hobby shop to me is over a 100 miles away. I will persevere and once again, thank you for your help, always welcome.
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Old Nov 07, 2013, 02:42 PM
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Bruce Abbott's Avatar
Hastings, New Zealand
Joined Jan 2001
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Quote:
Originally Posted by Very old timer View Post
I found that the problem followed the same stick assembly no matter whether it was plugged into the elevator or throttle plug on the board. However, when I tested the wiring and the individual potentiometers on the board, they all gave the same readings !!!!
If the elevator is stuck in the center then the pot wiper must be disconnected. Check the plug, wiring, and connections on the pot. If they are all OK then measure resistances between the 3 pot terminals. With the stick centered you should get ~5k Ohms between the two outside terminals, and ~2.5k from the center to either end.

If both center-to-end measurements add up to a lot more than 5k then there is a problem inside the pot - which could be dirt on the track, a cracked track, or a bad connection from the track to one terminal. You can fix cracks and bad connections with conductive silver paint.
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Old Nov 07, 2013, 05:28 PM
York Electronics
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Dallas Tx USA
Joined Apr 1999
2,505 Posts
I've had the same problem with the DX5i. It was a bad POT.

Long story short, I gave up on finding a new one and fixed the one in the transmitter.

The problem revolves around the "rivet lugs" on the pins of the POT. The "tightness" of the lugs was the issue - they were not connecting to the pads well enough.

I removed the POT and used a center-punch to re-tighten the rivets. This was done with MUCH caution. Applying to much of a strike force to the rivets could have broken the base PCB. I got lucky and not only didn't break the POT, but it fixed it too!

Also, mine was intermittent and for a while. I was convinced it was a dirty POT, but the problem kept returning. I must have took the transmitter apart and measured the POTs 10 times before I figured it out.
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Old Nov 08, 2013, 07:18 AM
Dave the Rave
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Joined Jun 2007
870 Posts
When the Spektrum radios were first introduced, there were a lot of pilots in a lot of places who were experiencing unexplainable crashes and problems with the new systems. A lot of guys wanted to blame the technology, but Spektrum correctly argued that the technology was sound, and had actually beeen around for a long time. Nevertheless, a lot of planes were lost before the problems seems to fade away. I have always believed, based on my experience with some of the guys in my club who had the radios, that the problem was due to lack of quality in the radios themselves, not a problem with the way they were supposed to work. Bad pots are a perfect example of a problem that could happen only for a split-second, yet cause you to lose a plane. I'd recommend replacing BOTH pots, maybe even order some better ones from somewhere. Hope you get it fixed!

David
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