DX8 (old model) won't calibrate

[miniplane]

Hi,

We are looking for some help... we have some trouble with our DX8 (old model):

As soon as we power it on the throttle alarm starts. Alarm happens for all the plane models.

When checking the monitoring screen we see the throttle minimum at -50 instead of -129.

If we try to calibrate the sticks, the throttle stick won't calibrate. Right stick and the knob calibrates.

Has anybody any suggestion ?

Thanks,
Adrian & Alexis.

[Sempai-mj]

Good question , I can't help as I'm a Futaba guy.

[drgilo1973]

the throttle stick must be down also the flaps and gear must be up then turn on ur transmitter and tell me what happened after

[miniplane]

Thank you for your ideas. They reassured me that I didn't miss anything in the configuration . I got also Ted's (Shop)feedback to my problem description: ship to repair. No feedback from Horizon Hobby support....

I opened the transmitter believing the variable resistor (pot) of the throttle was bad. Once opened, I saw that one of its soldering was a cold solder (not as shinny as the others). I measured the total resistance of the pot and it was unstable(it should be around 4.4KOhms). I soldered again all the pot's connections and then, I soldered the others gimbals pots.

After closing the transmitter the calibration went smooth and the throttle noise at lower position of the throttle disappeared. My son tested it yesterday with his planes.

I would share some observations (the DX8 was bought 2 years ago):
- the opening requires removing partially the rubbers: only one corner for the back rubbers and only one half for the side rubbers.
(check this video to identify location of screws and the parts that need to be removed https://www.youtube.com/watch?v=r7Klo-avfog)
- Initial glue on rubbers is still sticky and after it is assembled back it is like new.
- Don't tight too much the front screws, gimbals may become stuck.
- Tighten also all your switches since it is opened.
- Removing the throttle gimbals requires to loosen all the screws of the main PCB. No need to remove the PCB. You need to remove a small PCB keeping the switches connections.
- the pots do not resemble with the pictures/videos on youtube: they have a small, square and black plastic case.

I've made photos during the repair. If you have to do same repair, I will share them.

Thanks,
Adrian