Orig. Jumper T8SG - Channel 4 suddenly dead

Hi experts,

Since so many people here have experience with the Jumper transmitters, I'm asking here although it most certainly is a hardware problem and not Deviation related.

I bought the original T8SG soon after it was released, and it has worked flawlessly ever since. But a few weeks ago, I wanted to fly one of my quads, and find Channel 4 (rudder) not working anymore. I tested with different models on the Channel Monitor, and it is really just Channel 4 that is absolutely dead, not the slightest flicker on the monitor for that.

It did work 3 days earlier, and there was nothing in the meantime that could have caused any damage. The gimbal (mode 2) moves fine, I also opened the radio and couldn't see any physical signs of electrical damage. All wires and plugs are good, the gimbal still visibly moves the potentiometer...

So what on earth is going on here? Any possible cures? Can I replace parts, or the whole gimbal? I have sought the web for recommended replacement gimbals and couldn't find anything.

Btw., I have in the meantime also reflashed (and updated) the DeviationTX firmware, just to be sure it wasn't a software glitch. The update went fine, but the problem is still there. No Channel 4... Also, it does still exist with a completely fresh model. So it must be a hardware fault. Likely the end of this device.

Thank you so much for any insight!

M.

Have you tried creating a completely new model ? Have you tried doing calibration ?

Otherwise get a test meter and start tracing for electrical problems.

Hi, thanks for the reply.
Yes, I tried the completely new model and calibration.
I own a multimeter, but frankly are not very competent in using it with electronics. I have no idea what I should be looking for here...

Where are you based ?

propnut wrote: Where are you based ?

Germany, near Cologne. If you are in Europe I would be happy to ship the thing to you for tinkering around with, if that really is the background of your question?

I think I have excluded the gimbal in the meantime. Opened the case again, dissassembled left hand gimbal, exchanged plugs for rudder and elevator on PCB, and the suspect gimbal 'channel' does something when moved to the other plug. Also ripped off the gimbal wires (they were pretty worn out where they are being bent, it appeared) and resoldered them in the process, but no difference.

In essence, I would need to check the board for a fault, and then have the capacity to mend/replace the faulty parts, which is most probably out of the question for me. Time for a new TX, I'm afraid. Those TXs are still the single most expensive single piece of equipment in the hobby besides the goggles, it seems. I bought a BetaFPV Lite 2 to bridge the gap and it does the job for the moment, but I still want a 'real' TX again...

Yes that is what I was going to suggest but I am in the UK (not really part of Europe anymore )

Can I suggest you consider getting a RadioMaster TX8 from Banggood. They are REALLY cheap at the moment especially if you wait for a voucher. They are exactly like the T8SGv2 Plus only black.

Otherwise get a RadioMaster TX16S. It uses OpenTX which TBH I see having more life and development moving forward as ZERO seems to be happening in Deviation anymore. The Multi-protocol module in OpenTX already supports way more protocols.

Hi - thanks for the suggestions, that is exactly what I was considering myself, so I feel quite reassured now! TX16S is sold out in Germany everywhere ATM, but I'm not in a hurry after the Lite Radio 2 proved to be working okay.
I also wrote a PM about the repair idea.

Thanks for your time and advice!

Normally it is one of the wires, to the pot. From the outside they can look fine but internally the copper can be broken as they are bending when moving stick at the same spot. Exchange/Swap the connector + pot, from other channel to channel 4 and you'll can check if problem moves to the other channel.

Fernandez wrote: Normally it is one of the wires, to the pot. From the outside they can look fine but internally the copper can be broken as they are bending when moving stick at the same spot. Exchange/Swap the connector + pot, from other channel to channel 4 and you'll can check if problem moves to the other channel.

I believe I already did that, but might just try again more systematically, to be completely sure... Thanks for the suggestion, anyway!

To wrap this story up: I again checked that it is better the wires nor the potis, then gave up in frustration, as working on the controller board is beyond my skills.
Then, the Beta FPV Lite Radio 2 I had gotten as replacement started acting up. First, a wire/solder joint broke on the left gimbal. Fixed that, flew again. But only a flew flights later, the same gimbal started acting up with really twitchy yaw movements. Took me forever to grasp that it was not my quads acting up, but actually a problem with the TX. A few hours later of fumbling with that gimbal I found reports on the web about the Lite Radio 2 often being affected by failing potentiometers with the exact same symptoms I had. Sigh.
After another 48 hours without flying it struck me that I could try moving a gimbal or potis from the T8SG to the Beta. And yes, THAT WORKED. I switched over the complete left-hand gimbal assembly, had to move the wires around in the plugs, but was done with the whole thing in about 70 minutes including trial and error.
Still, I also ordered a RadioMaster tx in the meantime. I clearly need a backup radio, I have learnt...