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Trainer ports (DSC) and the plugs that use them.

Wayne

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Have you ever used the trainer port on your FrSky radio and had some issues? Maybe it worked great, or maybe it occasionally worked, or worse yet, refused to work. Well, it turns out the issue may be the plug you are using. Seems that these plugs "standard" is a bit out of whack, and differences have popped up over the last many decades that these little plugs have been with us. Take a look:
trainer plugs.jpg


Here is a quote from the Jake that took this picture and sharted his findings over on the OpenTX board:

I learned way more about mono/stereo connector variability than I ever wanted to know in the last several days. I bought a stereo -> Mono adapter (on left) which I tried with the stereo connector coming from my headset with little improvement in connectivity from just using the stereo jack. I also bought an actual trainer cord, which is just a mono male - male extender, that is on the right. The center is of course the original stereo jack originally on the headset. Look how similar the trainer and stereo jacks are, and how dissimilar the mono converter jack is. Much wider insulator area. I also bought a mono jack that I could solder onto my headset cable to replace the stereo one, which I tried and got inconsistent connectivity. That jack is not in the picture, but looks identical to the mono jack on the left which also does not work. I am getting around this in my case by connecting both the bottom and center conductors in the stereo jack to the gnd connection from the headset and just the tip to the signal from the headset. I my case this seems to be reliable.. We are getting burned by these manufacturers not following standards. FrSky should not be using a stereo connector in their radios. I am sure this was long ago spec'd as a mono connector. They are little used these days and I bet FrSky can get stereo connectors for 2 cents less than specifying mono. The headset guys are doing the same thing, not following a standard in place for many years, And the manufacturers of the jacks seem all over the place as to what the mechanics of a mono jack are supposed to be. Your mileage will vary with these connections. Not to bitch too hard at FrSky, I bet most of the radio manufacturers have this randomly implemented.

This style trainer port has been used by many manufacturers in the hobby for decades, and I suspect we have all run into this issue on and off over the years. My hat is off to Jake for spotting this issue and calling it to our attention.

We recently had a customer that was trying to get the head tracking on his goggles working, once he changed the connector for the correct style all was perfect. Hope this will help others!
 

P.I.Engineer

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i'm having this issue currently. I'm not sure from the above post on how to fix the issue.

what type of plug is needed? the stereo?
 

Alois

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Standard is mono as I recall.
But with my x9lite-S also stereo works.
Can you tell me what radio and what OpenTx version you have.
There is also a problem with some radios (x9lite and qx7-Access) with the Opentx version 2.3.12 till 2.3.14
In this case master/jack is not working (when calibrating you see that the radio as Master does not see the slave)
X9D-2019 had the same problem (was already fixed in 2.3.13)
Problem is to be fixed with 2.3.15 for x9Lite and Qx7-Access.
 
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