The signal range on the ch.2 (pitch) of my turnigy 9x was dramatically reduce from about 1000-1800 to 1600-1800. While other channels remain at about 1000-1800. Does anybody know what could possibly cause this?

Notes. 

  • Yesterday I opened up the tx to change the mode of the tx from mode 2 to mode 1 which only required the changing the side of the spring.
  • After changing the mode, I recalibrated the radio and the radio seems to work fine.
  • Today I try to fly it but notice that the front motor seems to be spinning faster than other ones, so I try check the escs and motor and all seems to be working fine and later found out that the signal range on the ch2 is only 1600-1800 which probably causes the quad to think that I'm pushing the pitch stick down and so the front motor spins faster. (I'm using + configuration)

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you didnt play with the endpoints at all ?

You could have accidentally done something inside the TX.  Sounds like something is shorted out or the pot or leads on the pot are damaged.  Check if the pot leads are touching.

perhaps the pot physically came apart during the spring change, i would bet the pots are nasty quality in a 9x

sorry, but what is a pot.

http://www.google.co.uk/imgres?num=10&hl=en&biw=1366&bi...

sorry for the long link, but a pic speaks a thousand words , look for something similar in the 9x and make sure it isnt fooooked

I assumed that this is the pot, but I don't see any damage on it.

(And somehow the image is upside down)

there are four of them , two on each gimbal,

do you have a multimeter to check the continuity and resisitance of each pot?

I think I got the wrong one the first time, that one is probably for the horizontal movement. Now this one is for the vertical movement on the stick that I'm having trouble with.

I do, but I don't know how to check.

OK, I have check, and this is the observation I got.

  • I check the voltage between the top and middle or middle and bottom solder joint on the pcb connecting the wire to the pot. The voltage changes as I move the stick, so the pot is working, but the voltage range may be smaller than it should.
  • If I apply pressure to the far end of the pcb ( the end with wires), the signal range is restore to normal, but when the pressure is removed, the problem came back.
  • I assume that the pcb is only there to connect the wire to the pot, so I checked the continuity and all of them is ok.

So, from the observation above, do you have any idea what is causing the problem. I know that if I apply the pressure to the wire end of the pcb, the problem will be solve, but I'm afraid that the problem will come back if the glue is loosen or the pressure is removed.

ok , so you have determined that there is a problem physically inside the handset,

what i would do is check the continuity from the legs on the pot to the furthest end of the wire for each leg, it should beep, or go from 1 to 0

then i would check the voltage change across the pot on all 4 of them, that way you can be sure that there is a problem if one of them is different,

the pressure fixing it seems to make me think there is either a dry joint, or a break on the PCB.  either should show up with a continuity test,

make the cont test, and at the same time apply pressure, and you will probly see varying measurements on the multimeter,

make sure also that the pressure being applied isnt moving some other component in the handset, for example if there is a pot directly beneath the board, or a cap ,

I would guess at a dry joint or broken wire, you have to try and determine which it may be

I have checked the voltage on different pots and have found that normal ones have a range between about 0.2 - 4.7 V, while the faulty one goes from 3.2 - 4.9. However, if I apply pressure to the wire end of the pcb, the faulty one will become normal (0.2-4.9).

Since applying pressure to the wire end of the pcb actually means apply pressure to the joint between the pot and the pcb, I think that the problem is with the joint on the legs of the pot.

If it is a dry joint, how do I fix it? re-solder those joint? Is the pot easily damage by heat from the solder iron?

If it is a pcb problem, is it possible to just directly solder the wire to the pot?

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