Taranis X9D Plus SE Antenna problem

Hardware help and support for the FrSky Taranis
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HowardTheDolphin
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Taranis X9D Plus SE Antenna problem

Post by HowardTheDolphin » Thu Jul 05, 2018 9:22 pm

Hi,

I'm looking for some help/advice with an issue i'm having with my Taranis X9D Plus SE.
I've been searching for a relevant thread and not found anything as yet, so hoping someone might be able to help, or at least point me in the right direction.

I'm not the most savvy with the radio side of things, particularly openTX, so apologies if this query is a bit stupid!
About 2-3 months ago, I built my first FPV freestyle drone and bought the X9D Plus SE. It's currently overkill for what I need, but I figured the additional features might come in handy as i progress in the hobby.

About 2 weeks ago, I decided to open the Tx to remove the ratchet on the throttle, and in the process of opening the case, I unfortunately pulled the antenna connection away from the board. Having previously opened a futaba 14SG with no issues, I wasn't expecting the Antenna to be in such a position as for this to be possible, and really didn't use all that much force when separating the case halves, so was surprised that it came away so easily.

Anyway, I work with people that do circuit board assembly and soldering, so had 1 of my colleagues re-solder the connections, but when I powered up the transmitter I received the "Antenna is Defective" warning.
When we checked it after the warning, we noticed that the ground and signal pads on the internal XJT module had continuity, and are assuming this is the source of the problem.

I have since purchased a replacement backboard, but when my colleague soldered the antenna to it earlier today, again there was continuity between the ground and signal pads. We made sure the battery was disconnected and removed when he performed the soldering of the antenna, so don't think that could be causing any issue.

We've looked for a schematic, but can't find 1 online, and have seen forum posts where people are discussing the lack of such data and that FrSky seem unlikely to provide 1.

Has anyone experienced anything similar to the above, or is knowledgable enough with this radio to understand what might be going on?

My colleague and I are a bit confused as to how the pads can have continuity (a potential short?) on the new board given that we ensured the battery was removed at the time the work was carried out.

Any help or advice would be greatly appreciated.

Thanks for reading if you got this far!

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Kilrah
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Re: Taranis X9D Plus SE Antenna problem

Post by Kilrah » Sat Jul 07, 2018 9:46 am

A DC "short" is normal on many RF circuits. BTW testing for that with a multimeter can be destructive.

If 2 boards do the same and the antenna was properly soldered on both and with good ESD protection measures then maybe it's really the antenna that's faulty. Pulling on the cable can have ripped the core wire inside the insulation for example.

HowardTheDolphin
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Re: Taranis X9D Plus SE Antenna problem

Post by HowardTheDolphin » Sun Jul 08, 2018 7:29 pm

Thanks for the reply Kilrah.

Apologies if I've not followed correctly, but are you saying that having continuity between signal and ground pads on some RF circuits can be normal, implying that the replacement board may actually be functional after all?

Just to confirm, I have not powered the transmitter with the new board installed as we were seeing continuity both when the antenna was installed, and again between the signal and ground pads once the antenna had been de-soldered. I didn't want to potentially cause further issues by powering up the Tx if it wasn't connected properly.

Is there a recommended method for checking functionality of the board without using a multi-meter (if using a DMM may be potentially destructive)?

I tried to find a replacement antenna as well in case it was now faulty, but I'm struggling to find the correct antenna with SMA connector, and when speaking with banggood (whom I purchased it from), they just keep linking me back to the old style antenna which doesn't have the SMA connector, which wouldn't be a correct fit for the X9D plus SE model.

Thanks again for the reply and suggestions. Would be great if I could pick your brains further on this over the coming days.
Really want to get back flying!

All the best

HowardTheDolphin
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Re: Taranis X9D Plus SE Antenna problem

Post by HowardTheDolphin » Tue Jul 10, 2018 9:12 pm

Just updating this thread for anyone that might run into a similar problem.

Much like Kilrah suggested, I've had confirmation from the FrSky EU service centre that the "Short" causing the continuity on the ground and signal pads is due to a built in ESD protection on the circuit.

The original antenna has been soldered onto the replacement backboard, and the Tx is working properly again.

Still don't know why the original backboard that I accidentally pulled the antenna away from doesn't work, and also confused as to why when opening a friends original X9D plus (non-SE version) there was no continuity between the signal and ground (there was and still is on mine even though it now works again).

Thanks for your help Kilrah.

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Kilrah
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Re: Taranis X9D Plus SE Antenna problem

Post by Kilrah » Wed Jul 11, 2018 6:04 am

The ESD protection was not originally there, it was only added at some point after too many people shot their board while adding an SMA pigtail.


athertop
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Re: RE: Re: Taranis X9D Plus SE Antenna problem

Post by athertop » Thu Jul 12, 2018 8:34 am

Kilrah wrote:The ESD protection was not originally there, it was only added at some point after too many people shot their board while adding an SMA pigtail.
That is good to know! Wondering how we could identify a board with esd protection - and if those replacement boards from banggood have this feature.
Incidentally, after having replaced the backboard twice in my original x9d+ because of terrible range after the antenna mod, and still having terrible range, making me retire the Taranis for 2 years after buying a new one, I decided this weekend to replace the sma-rp pigtail with rg316, to cut it to 82mm and to solder direct, and my low swr and decent range has now returned - so my old Taranis is fully functional again - meaning that the latest back board wasn't broken after all. The key here was not the coax or the length even, but the direct soldering and making the exposed conductor as short as possible. Sorry to hog the thread but may be useful to someone.

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bob195558
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Re: Taranis X9D Plus SE Antenna problem

Post by bob195558 » Thu Jul 12, 2018 10:17 am

Could buy the external XJT module and which could fix all your troubles too (https://alofthobbies.com/frsky-xjt-jr-g ... odule.html).

erSky9x firmware (ersky9x for Taranis Plus) works real well too (http://www.er9x.com/).
Last edited by bob195558 on Thu Jul 12, 2018 10:46 am, edited 1 time in total.
ErSky9x on Taranis, Sky9x, 9Xtreme, Er9x on 9x with Smartieparts Programmer with TelemetrEZ Board
3D Printing: (http://openrcforums.com/forum/viewforum.php?f=85)

athertop
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Re: RE: Re: Taranis X9D Plus SE Antenna problem

Post by athertop » Thu Jul 12, 2018 10:26 am


bob195558 wrote:Could buy the external XJT module and this could fix all your troubles too (https://alofthobbies.com/frsky-xjt-jr-g ... odule.html).
I did that also, but initial testing showed range issues with this too, so ended up with a new taranis. I never gave that much time to figure source of range issues. Also built ULRS module and Moxon antenna, which I use with Taranis on fx61. That does 30miles so no range issues there

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bob195558
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Re: Taranis X9D Plus SE Antenna problem

Post by bob195558 » Thu Jul 12, 2018 10:54 am

Most people use the transmitter antenna that comes with there Taranis.

Sometimes range is affected by where you are doing your testing.

You may want to look at the external TBS Crossfire (https://alofthobbies.com/tbs-crossfire- ... undle.html).
ErSky9x on Taranis, Sky9x, 9Xtreme, Er9x on 9x with Smartieparts Programmer with TelemetrEZ Board
3D Printing: (http://openrcforums.com/forum/viewforum.php?f=85)

athertop
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Re: RE: Re: Taranis X9D Plus SE Antenna problem

Post by athertop » Thu Jul 12, 2018 10:59 am


bob195558 wrote:Most people use the transmitter antenna that comes with there Taranis.

Sometimes range is affected by where you are doing your testing.

You may want to look at the external TBS Crossfire (https://alofthobbies.com/tbs-crossfire- ... undle.html).
I'm happy with ULRS thanks with full duplex 19200 telemetry uart. Don't think this is available on XF as of yet - I have considered DL though, the choice purely based on its telemetry capabilities.

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bob195558
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Re: Taranis X9D Plus SE Antenna problem

Post by bob195558 » Thu Jul 12, 2018 11:29 am

Could use two receivers, one with each transmitter using internal for telemetry (opentx).

With ersky9x for Taranis you can choose which transmitter you want to use for telemetry, internal or external.
ErSky9x on Taranis, Sky9x, 9Xtreme, Er9x on 9x with Smartieparts Programmer with TelemetrEZ Board
3D Printing: (http://openrcforums.com/forum/viewforum.php?f=85)

athertop
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Re: RE: Re: Taranis X9D Plus SE Antenna problem

Post by athertop » Thu Jul 12, 2018 12:08 pm

bob195558 wrote:Could use two receivers, one with each transmitter using internal for telemetry (opentx).

With ersky9x for Taranis you can choose which transmitter you want to use for telemetry, internal or external.
But the LRS systems I mentioned allow any serial data through, multiplexed with the rc data, so full mavlink connectivity to the ground with just one tx, one rx, then on the ground BT connectivity to mission planner and frsky pass-through (using teensy converter) to awesome lua telemetry screen (ref: yaapu). It is the best LRS solution I have found to date.

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