Discussion Spektrum receiver blinking LED - what it means

[wjbite]

Originally Posted by velojet

This is directly contrary to what village_idiot advises in Post #1: "The only sure fire way is to connect the receiver first, then wait more than 2 seconds for it to start scanning for the TX, then power up the TX."

John V

Well I think that this is ANOTHER sure fire way to avoid a blinking light.
You cycle the Tx power (off then on) before you power the Rx.
This works AND avoids the dreaded possibility of motor starting because the Tx is not on (maybe a function of ESC characteristics).
Like I said, try it, you will like it, eh?
If you try it and it doesn't work please post that result - I think that VI's way is not the ONLY way.

Thanks,
Walt

[vintage1]

I found this thread on account of another person in another forum clearly demonstrating that starting a spark engine near a test rig caused his lights to blink.

Now although a spark is long enough to knock out a frame or two, its not enough to reboot the set..it is enough however if it corrupts the microprocessor, to do things like knock the program counter off the position its executing, erase flash memory, and possibly change RAM values.

Ive invited billydsrc to move his query here.

In the meantime, his video is worth reposting.

Spektrum 2.4 transmitter,RX problems with GAS motor (1 min 50 sec)

[BILLYDSRC]

http://www.youtube.com/billyd44444#p.../4/7pVeijWm-dg

Originally Posted by hrholloway

I have been using a DX7 AR7000 setup in electric planes for about two years now without any issues. Recently I installed the AR7000 RX in a Seagull Edge powered by a 20cc gas motor. Initially I had trouble with the throttle servo that would glitch at idle rpm. Problem went away when I replaced the servo with a digital one. The servo was located about 300mm from the engine and connected via a plastic sleeved metal pushrod with a metal on metal z-bend link at the engine side. (I know metal throttle linkages are bad but hey this is a DX7 and this is what came with the kit).

Fifteen flights later I decided to cyno the pushrod sleeve in place as the throttle control was not precise enough to my liking. I started the motor at home to test the throttle setup and found that the servo glitch had returned with a vengeance. I also noticed that the satellite receiver would start blinking at about 5Hz (5 cycles per second) as soon as the motor was running. At times the LED would go out completely and come on again blinking. The same would also occasionally happen with the primary RX. To my horror I found that if both the primary and the satellite LEDs were off at the same time connectivity would be lost completely and power cycling the RX would be the only way to restore the connection.

After stopping the motor the satellite receiver and sometimes the primary receiver would blink at about 5Hz until power cycled. Both receivers would then display solid until the motor was restarted after which the satellite receiver would immediately start to blink at 5Hz and turn off intermittently. The satellite receiver was further away from the motor by the way.

Replacing the metal pushrod with a plastic one solved the problem completely and after several flights and range checking with motor on both receivers display solid LEDs until switched off.

Although I have not found any documentation from Spektrum to support this my observations would indicate that a slow blink (2Hz) indicates a power dip and a rapid blink (5Hz) radio interference.

The sobering realisation is however that the 2.4Ghz system can suffer from interference to the point that all control is lost. All I had to do to accomplish this was cyno the sleeve of the throttle pushrod. Doing so must have enabled the metal on metal contact to be more consistent. This only happened with the throttle completely closed, as in fail safe mode, from which the receiver would never recover.

My Setup:
Seagull 78" Edge 540
Zenoah 20cc gas motor
16 x 8 prop
RX AR7000 with standard 6 x DS821 servos
2 separate 1500mah nicads for RX and electronic ignition

Radio power sequence:

TX on -> RX on -> fly -> RX off -> TX off

On electrics/gas setups I would suggest observing the RX with the motor off. Start the motor and see if the LEDs start to blink. If they blink you stand to loose your model.

Hope this helps save a model.


Regards,

Ron

[vintage1]

Glad you found the way in here. Billy, it looks like you have a way to reproduce this problem, and could do a whole lot of good if you are prepared to track this issue down once and for all. At least you aren't going crazy. There is a definite problem.

For what its worth, I half agree with the Spektrum people: No way is this due to radio interference at the 2.4Ghz end of things. BUT its happening alright.

So something else is happening. And my best guess its the high voltage pulses are screwing with the computer side of the spektrum.

To other followers of the thread I recommended that a suppressed sparkplug (resistor in it), or an actual resistor, or/and a resistive ignition lead, would be a good place to start, and foil shielding the receiver apart from its antennae, and shielding and ferrite ringing the wires going into it.

[sonicj]

thats crazy!

out of curiosity, i did some reading and found this document relative & informative! i guess 1:1 scale aircraft have the same battle to fight! the book's preview has a lot of good info, might even be worth a trip to the.... library! (*gasp)

[BILLYDSRC]

I know there are all kinds of things to make this happen. But when I called horizon hobby and asked them if this could happen they told me nothing that that motor puts out can interfere with 2.4 spectrum.and I have it on video and they DO NOT have a answer for me??????????? anyway that spitfire is in 1,000,000 pieces now....

[vintage1]

Originally Posted by BILLYDSRC

I know there are all kinds of things to make this happen. But when I called horizon hobby and asked them if this could happen they told me nothing that that motor puts out can interfere with 2.4 spectrum.and I have it on video and they DO NOT have a answer for me??????????? anyway that spitfire is in 1,000,000 pieces now....

Well in a sense, I think they are right. Its probably NOT interfering with the 2.4Ghz bit Billy. I STRONGLY suspect its interfering with the computer bit.

That's probably good news, because it means normal interference suppression techniques will work, as I outlined to you. I.e screen the receiver apart from its antennae, and put chokes on the wires going into it. And of course work on the HT side of the motor to reduce the interference there.

Now if you were ten miles way, not 4000, I'd be out there out of simple curiosity armed with soldering iron and various suppression bits..

[lazy-b]

I've been using a Spectrum 2.4 GHZ on my Gasser Helicopter, and most of my RC Buddies is using a Spectrum 2.4 on their Gasser Plane and Helicopter. Never encounter a single Glitches.

I think Vintage1 is Right, its not interering to 2.4 GHZ, but rather to its Microcontroller inside the Receiver.

I have also encounter a very similar problem with my Microcontroller Project......My Microcontroller Project works perfectly at my Home and Office, but when I put it in an Airport, it do not work properly.


Ellion

[BILLYDSRC]

JUST GOT THE TX BACK FROM HORIZON TODAY AND THIS WAS WHAT I GOT BACK FROM THEM.It was going into range check when I was flying. and there head tech did not catch it???????? and I got a video of it doing it!!!!!

Spectrum DX-7 NOT WORKING RIGHT (0 min 29 sec)

[lazy-b]

BillDSRC, Maybe its just a loose Battery Connection......this happen also to my Futaba Transmitter......I just open up my Futaba Transmitter and notice that the one of the Male/Female Battery connector, The Male Terminal connector is not so clean, it should be as clean as pure Silver, I just scrape it with a Hobby Knife until its clean up.

Its very difficult to Catch an Intermittent problem........I would suggest not to use the Transmitter until you able to Catch the problem.

[BILLYDSRC]

Well I just got off the phone with Horizon. They are replaced the DX-7 and the SPITFIRE with a Saito 100.

[Kambalunga]

"The servo was located about 300mm from the engine and connected via a plastic sleeved metal pushrod with a metal on metal z-bend link at the engine side."
A metall pushrod or a metall clevis direct to metall is a very very dumb thing!

[davensocal]

Regarding some satellites blinking and some not...


I saw this on a new 1222 installation (4 remotes).. During range checking, one satellite would report very high fades, or 999. Sometimes that satellite would also blink its LED.

The satellite was swapped out and the problem went away. Later, all the gear went in, and 2 satellites were found defective..

So, from my limited experience, if you have one satellite flashing only, you should investigate it for damage or bad cable.

[sunderll]

Hello all! I recnetly attempted a maiden flight of a DC-3 which has teo speed 400 motors and a 40 AMP controller for both motors. During assembly I of course operated all the controls many, many times with no problem. However, during the pre-flight check, I found that after arming the controller to gain throttle control and operating the ailerons and elevator numerous times, the light in my AR500 receiver would go out and the servos would no longer move. Also, there was a high pitch humming coming from the receiver. Once I turned everything off and on again, everything was fine until that scenario was repeated. Here are a few factors. Due to the usual cost considerations, I'm using two HS55 servos on the elevator and rudder and two 3104(I think, plane's not with me now) Futaba servos for the ailerons. This failure mode only occurs with the two aieron serovs unplugged from the "Y". If I leave one servo in, the failure still occurs. Is there any reason the Futaba servos wouldn't be compatible with this set up? I've tried many differnt batteries and it does it with the motors stopped, not running. Any help is greatly appreciated..thanks!!

[F-111 John]

Originally Posted by sunderll

This failure mode only occurs with the two aieron serovs unplugged from the "Y". If I leave one servo in, the failure still occurs. Is there any reason the Futaba servos wouldn't be compatible with this set up? I've tried many differnt batteries and it does it with the motors stopped, not running. Any help is greatly appreciated..thanks!!

Sounds to me as if you are running too many servos for your single ESC's BEC. Try using a separate RX battery for troubleshooting purposes. You might need to use a separate UBEC that can supply 5-6V with at least 5 amps.