9XR XJT module FAIL - Help!

Cant get your radio to work? General Hardware issues?
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Mid7night
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9XR XJT module FAIL - Help!

Post by Mid7night »

I've been having a problem with my new FrSky XJT module not working in my 9XR. It powers on, so I can bind a receiver to it, but the commands don't get through to the receiver. Is there a way to tell if one of the pins isn't connecting enough? How to know which one? Any mods to fix this?

I've verified that the XJT module itself works fine, I put it in an old JR and it works fine, talks to all my receivers and controls everything just great. My problem is definitely somewhere in my 9XR.

I also connected the pins from the 9XR module bay via jumpers to the XJT module, to hopefully rule out a physical connection problem, but it still wouldn't talk to any receiver. Again, it still powered on and bound, but commands don't get through.

I haven't opened the radio yet, but I'm not averse to it, I'm comfortable around screws and wires. I just don't know where to look or what to look for.

How can I determine where the signal is being dropped?

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ShowMaster
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9XR XJT module FAIL - Help!

Post by ShowMaster »

Just thinking.
You didn't mention your firmware version. Is it the provided HK er9x?maybe you've got a mode select issue in the model memory your using?
I'm thinking I'd should be ppm and 22ms. Try + and - shift.
Select a totally new unused model memory just in case the one you're using is messed up.
That happened to me. A new memory and it all worked. I erased the one I was using and started over and it then was ok.
Is this the only module you have for your 9xr? I'm assuming yes.
Others will want your answers to help you out so more when you post them.
A scope would tell all in seconds. It's posable a connector isn't seated and no ppm is getting to the top module pin.
Mid7night
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Re: 9XR XJT module FAIL - Help!

Post by Mid7night »

It is a totally stock 9XR.

I'll try the PPM and shift you suggest. (PPM is default anyway, I believe)

Model-memory-slot shouldn't be an issue, but I'll try a new on as you suggest just to be sure. The reason I say it shouldn't be a problem is because this radio-module combo was previously working when I first received the module.

It IS the only module I have now, unfortunately. I used to have an OrangeRx module, but I sold it to fund buying the XJT. I regret selling it so soon, I should've kept it for troubleshooting.

I don't have a scope, maybe I can borrow one from my local electronics shop... I presume buying one to troubleshoot this would likely be more than just buying a new 9XR. ;)

Thanks SO MUCH for all your questions and suggestions, I really want to figure out how to fix this, I don't want to just throw it out and but a new one. I'm a long-time mechanical-tinkerer, so I want to be able to fix this. :D
Mid7night
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Re: 9XR XJT module FAIL - Help!

Post by Mid7night »

OH. MY. GOOOOOSH.

Tried a new model-slot.....BAZINGA. It worked!

Then I noticed it "jumping" a little, so I gave the radio a few good shakes, and it periodically would cut out. So I switched back to one of my previous model-slots, and held the module firmly in the back, and it worked again! So it wasn't really the model-slot issue.

I feel SO dumb that it was a simple pin-seat problem.

Now off to hack the module to make sure it seats firmly every time.
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ShowMaster
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Re: 9XR XJT module FAIL - Help!

Post by ShowMaster »

If it all was working and the module works in a jr radio it should be something simple with the 9xr.
The PPM output from the 9XR is on the top module connector pin. You have power because the module you say powers up and binds.
This tells me you either have a bad top pin connection or your 9XR isn't outputting a ppm signal.
Good reason to try a new clean model memory.
Does your module seat fully in the 9XR? I can't remember if my case had extra raised plastic around the module make pins when I got it. I know we have to remove it on the newer HK 9x cases to allow the DJT to fit flush.
Is there any raised plastic around you pins?

Maybe push on your module while trying to work a servo in case that makes contact?

The good news is that HK sells the whole electronics boards for $7-8 I think.
If all else fails that's a fix.
As for a scope. There are free PC programs to use your PC as a simple scope. Maybe it's another last thing to try.
Any chance you fly with others that may have a Frsky or other module that fits your 9xr you could try?

Daedalus66
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Re: 9XR XJT module FAIL - Help!

Post by Daedalus66 »

I've had various problems with module contacts in different transmitters, including JR and with modules including the Spektrum DM9. In some cases, the answer was to put a balsa wedge into the space between the tab and the module. In another, it was to bend the pin into a very slight curve. One 9x would never work reliably with the Spektrum module because the pins were slightly too short.
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ShowMaster
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9XR XJT module FAIL - Help!

Post by ShowMaster »

Thanks to a reply from MikeB we already have a ppm tester built into our radios.
Try this to verify the ppm is on pin 1 (top pin) and is correct.

[quote="MikeB"]It's called a TRAINER CABLE. You switch the Tx on, plug the trainer cable in, then hold the tip of the other end of the trainer cable on pin 1 of the module connector.
You get the first 4 PPM channels displayed at the bottom of the trainer menu.

Mike.

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