Frsky Taranis Rx lock out - RC Groups
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Sep 04, 2016, 09:05 PM
Registered User
jsparky's Avatar
Alert

Frsky Taranis Rx lock out


Since I could not find another thread dealing with this sort of thing here goes..

The Setup

Great Planes Revolver 70 .. RCG 20cc gasser .. X8R rx

Near the end of of last year I was at the field and doing my usual preflight check.. when the engine suddenly stop and all flight controls stopped responding.. the plane was DOA ... I shut of the plane and transmitter and rebooted everything and all controls came back and the engine started... this happened several times.. ok so this plane doesn't fly today.. At home I started to tear into it.. I changed the Rx the ignition the wires the battery ,, everything... even to the point that I held a Rx in my hand with only a battery attached near the plane and the Rx went into a lock out condition.. and the only way to get it back was to turn it off and back on again..

The only thing I had not changed was the plug.. so I put in a new plug and the problem went away.. put the old plug back in problem came back... Ok so I figured something internal to the plug was creating some kind of stray RF signal that some how locked up my Rx.. Not a good thing to have happen but what are the chances of this happening..

Well this year after about 6 flights or so on that new plug the problem came back again suddenly.. I borrowed a plug from another member and tested it and again everything worked fine..

So it struck me kind of funny that two plugs could fail in the same way as to cause enough RF interferance to lock up my Rx..

So I tore apart everything and I do mean everyting looking to find out why.. I did resistance checks on new plugs compared to the one that I thought had failed.. no damage to the plug in anyway..

But !!! inside the plug cap... there is a spring that is suppose to touch the lead on one end of a 1K resistor that goes to your lead from the ignition module .. First off ... there was little to nothing of that spring inside the plug cap.. and second the was barely anything of the lead from the resistor coming into the cap for the spring to make contact with... examining the leads of the resistor I found high voltage scoring on the lead that is suppose to contact the spring which contacts the plug.. This was the source of the arcing that caused the stray RF signals.. Not the Plug..

Now before someone says that it was bad shielding around the plug cap.. nope... that was checked as well... All shielding was in place and good contact..

Why a new plug would fix things I can only guess that it may have slightly less resistance than even a slightly used one and therefore changing the conditions..

But I have fixed the problems with the ignition leads and re-installed the orginal plug and everything is now working fine..

The ALERT is to the potential problem of a FrSky Taranis Rx going into a lock out condition as a result of stray RF generated by a bad high voltage ignition.. This problem cannot be diagnosed by listening to the engine run as it will not cause any noticeable difference to the engine running..

If your FrSky Rx is showing a slow flashing red light... your in a lock out condition.. and only powering off the Rx will reset it again..
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Sep 04, 2016, 11:12 PM
Sagitta Fanboy
Quote:
Originally Posted by jsparky
The ALERT is to the potential problem of a FrSky Taranis Rx going into a lock out condition as a result of stray RF generated by a bad high voltage ignition.. This problem cannot be diagnosed by listening to the engine run as it will not cause any noticeable difference to the engine running..

If your FrSky Rx is showing a slow flashing red light... your in a lock out condition.. and only powering off the Rx will reset it again..
It's worth noting that spark-gap interference such as you were experiencing is broadband and would cause issues with any 2.4 system (and most likely with any radio system, even FM or AM).
Sep 05, 2016, 02:39 AM
Registered User
Zeeb's Avatar
Oh yea gods.... there is a problem with the Taranis? You'd never believe it from what the fanboys have been saying.....

That said with tongue firmly planted in my cheek...

As mawz said, there isn't a radio system out there that can handle the interference created by loose sparks intended for the sparkplug and no where else.

I'm a bit confused at this point; how come every problem I see for the last couple of years is blamed on the radio??????

Not even "dumb thumb" crashes happen anymore? It's ALWAYS the radio's fault.

Get a grip guys, YOU are responsible for a competent setup of the model. The radio cannot correct everyone of your screw ups.
Sep 05, 2016, 08:36 AM
Registered User
jsparky's Avatar
As Mawz has said .. it is a broadband spectrum ... as to how far these stray RF signals can reach is only guess work without a crap load of fancy equipment and a dozen engineers ...

And yes it can happen to any radio system .. It is not restricted to the Taranis .. the effects could be and most likely be different in each radio brand out there..

And the worst part is .. it may not even come from your own plane..

You could be flying in formation with a buddy and his plane is giving off stray RF...

Give a whole new meaning to the term

" I WAS SHOT DOWN "

Here is a prime example.. buddy of mine got this 50cc plane from someone and decided he would never fly it.. so he traded it to me..and after checking it over... wonders to be found in used airplanes but check the pics... this ignition was installed in an 89 inch 50cc extra 300 and the guy was flying it like this..
Feb 07, 2017, 11:29 AM
Registered User
I'm having an issue with an EDF that sounds similar to you. Once receiver locks out it doesn't come back.

https://www.rcgroups.com/forums/show...ig21-Need-Help
Feb 07, 2017, 07:10 PM
Registered User
jsparky's Avatar
Quote:
Originally Posted by yellowbird2800
I'm having an issue with an EDF that sounds similar to you. Once receiver locks out it doesn't come back.

https://www.rcgroups.com/forums/show...ig21-Need-Help
Oh sh*t ... that is scary.. I never had a problem with the one EDF I have flown.. but not to say you couldn't.. As to the cause of it... would be guess work.. but look for a connection point that may be arcing.. since an electrical arc is the simplest form of RF transmission.. and the most likely cause.. It could be any place from your motor to your battery.. pull all of the connection points apart and look for traces of arcing.. if you have solder joints inside of heat shrink.. it could be in the solder joints.. bad solder joint in the ESC.. many cold solder joints have caused problems in electronics and with the high power of todays electric models it could be a potential point of arcing.. it could even be inside the motor if a winding has come loose and rubbed against the case...

If you find it... Post it here... if it happens to enough people.. then FrSky will have to be notified.. and hopefully fix the software to reboot itself..
Feb 08, 2017, 07:35 AM
Registered User
Jsparky, This edf has a max amp of 98 amps on 6S with an ESC that works fine but probably not highest quality and doesn't really need to be for the price so I'm sure there could RF noise from it. I've added a ferrite ring to see if that stops the lockout. My biggest concern is the total lockout that will cause an uncontrolled crash. To me this is unacceptable and needs to be fixed. Even if this plane appears fixed I will always wonder when an RF issue will cause it to come crashing down. Not the confidence I was looking for when I switched to FrSky.
Last edited by yellowbird2800; Feb 08, 2017 at 09:43 AM.
Feb 08, 2017, 05:33 PM
Registered User
jsparky's Avatar
Quote:
Originally Posted by yellowbird2800
Jsparky, This edf has a max amp of 98 amps on 6S

Not the confidence I was looking for when I switched to FrSky.
6s at 24 volts and 98 amps is a pretty hefty chunk of hydro.. way more than enough to create an arc that could interupt any Rx... This sort of thing is not isolated to FrSky.. maybe just the way the Rx handles the stray RF.. I have heard others say they have had various problems related to this sort of thing .. you just need to find the source of it.. I don't think that even a cheap ESC would generate enough RF to cause a problem unless there was something seriously wrong with it..

I originally had an HK red brick ESC in my habu.. and it would randomly start the fan for a second or two.. and then stop.. not to say but it went the way of the dodo bird..

I too tried the ferrite ring thing... and it did nothing for me.. another thought... but where are your antenna leads in relation to any wiring that carries the high current.. you might also have an inductance problem if they are too close to heavy high current areas..

You know that you can change antenna leads to different types.. up to 60cm long..

Like I said you need to find the source of the RF.. I am still confident in my FrSky equipment
Feb 09, 2017, 03:59 AM
Proud to eat Kraut ;-)
Julez's Avatar
It seems to me a lot of people are missig the point. This thread is not about RF interference. It is about an RX lockout. These are different things.
Intererference just means that RF signals are blocked by another RF source, and although the RX is working fine, it can't hear the RF signals intended for it. This can indeed happen to any radio system.

This thread, however, is about the RX locking out due to an internal error. It should be able to respond to the RF sinals when the source of interference stopped transmitting, when the engine stopped. It did not when there were valid signals and no RF interference any more, and this is the problem.
Good computer systems have a watchdog which resets the sytem when it "hangs" or is stuck in some kind of "loop". As the red LED was reportedly still blinking, this means that pats of the system were still alife, but some not. This is a kind of "zombie state" and indeed a design error.
Feb 09, 2017, 05:07 AM
Registered User
jsparky's Avatar
Quote:
Originally Posted by Julez
It seems to me a lot of people are missig the point.
Nope .. Just.. YOU


It is about RF locking out a RX...
Feb 09, 2017, 05:47 AM
Registered User
Quote:
Originally Posted by jsparky
Nope .. Just.. YOU


It is about RF locking out a RX...
Nope, Julez is right. RF locking out a RX temporarily is normal and nothing new. As soon as the RF source is eliminated the RX should re-connect, and it doesn't. That is the issue.

I have a theory why.... The basic FrSky RX has 2 main components: A STM32 main processor and a CC2500 RF processor. The STM handles outputs, inputs, failsafe, led's ect, basically everything you see working on the RX. The CC2500 is the RF chip and communicates with the TX. Both chips are running software and have a watchdog / reset routine that kicks in when all goes wrong. With the current issue failsafe is working and the red LED blinks indicating no connection to the TX so that means the STM is still working. That means the CC2500 is probably the issue and since it is the RF chip it makes sense that is affected by a strong RF noise. But why does the watchdog not reset it and start it again? It probably does... but that is an issue also. Why? The CC2500 receives configuration data from the STM on startup (like bind data ect) and that data is gone after a reset. If the STM keeps working it does not know a reset has occurred and does not load configuration into the CC2500....

This is how i believe how the system works using my knowledge about electronics. If i am correct a solution would be to check the CC2500 from the STM regularly and if a reset is detected the configuration can be re-loaded.
Feb 09, 2017, 08:01 AM
Registered User
I received an email from FrSky that they are looking into this issue an issue that I really doubt they even knew existed. My personal feeling is that FrSky seems to a be an agile company that will address this as soon as possible.

Hope you are right Tandango, if so than a FW update should fix the problem. Traveling all over southeast going to Flyins I don't see a ton of FrSky. In fact for all the Jet Meets I've attended I've only seen a few other guys flying FrSky not that there aren't a ton out there I just haven't seen them. Also belong to a quad racing group and of course FrSky is the most prevalent brand there. You would think they would have issues with RF but maybe the Flight Controllers has a lot of filtering built into them. With the introduction of the Horus and since it is a premium radio I feel there will be a lot of new guys flying FrSky. Better to find a possible issue like this now, even though I know it as actually only affect a few people, than later.
Feb 09, 2017, 08:23 AM
Registered User
Sorry JSparky I didn't answer your questions.

Yes 98 amps is a fair bit but I've flown big electrics for the last 10 years with systems of 15S and 180 amps. And I've had RF issues before but they were twitching servos, weird throttle arming issues and even a few short lock out issues. I've moved things around with out fixing the issue in this plane. The antennas are as far as possible from any wiring or the power leads. My first concerns was of inductance not pure RF since the power lead is very long. I never like to use a power lead longer than 18 inches from esc to actual lithium battery solder joint unless it has huge caps added. This esc has standard size caps and long power leads. That said I have owned three other Freewing EDFs that are set up in this way with out any issue so that probably has nothing to do with the current RF problem. Have installed a big RF ring, not the little hobby ones we've all seen and will try it at the field.
Feb 09, 2017, 08:24 AM
Registered User
mpjf01's Avatar
It would be interesting to know whether this issue happens with FRSKY receivers other than the X8R.
Feb 09, 2017, 08:32 AM
Registered User
It does with X6R and S6R for me. I have not tried a X8R in this plane.


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