Spektrum DX5E transmitter problems

[Gareth JonesParticipant @garethjones79649]

[Gareth JonesParticipant @garethjones79649]

In the light of a well known contributor's problems in binding receivers to a transmitter I thought I would enlighten the readership with my own experiences with some Spektrum equipment over the last few weeks.

We have two DX5E transmitters and a DX6i computer set. The DX5Es are now about 8 years old and for completeness, both operate on the DSM2 protocol, although I don't think that is relevant to our experience.

Over the past few years we have had two distinct problems with the DX5E sets. After a period of storage, we often found that the receivers and transmitters failed to link when they were switched on. My assumption had been that for some reason, they had become 'unbound'. Usually, rebinding them would restore operation but often multiple attempts at binding were required. All our receivers are genuine Spektrum items, a mixture of DSM2 and DSMX types but all should be compatible.

The second problem began to emerge when we started to use the MR200 marine receivers which seem to be on a slightly different protocol, neither DSM2 or DSMX but should still be compatible. When the receiver and boat were powered up with the transmitter already on, the motor would run briefly at full throttle in reverse. I was convinced this was something to do with the failsafe system. The instructions were to bind the receiver with the throttle in the required position for the receiver to adopt that as the failsafe and not assume the default of fully back. In an aircraft, fully back would normally be off, but in a typical model boat set up with the throttle spring loaded to mid position, fully back will give full reverse as the failsafe. Despite repeatedly following the instructions and setting the throttle to the mid position when binding, the failsafe always gave me full speed in reverse.

The story will be continued after tea.

Edited By Gareth Jones on 15/07/2017 17:37:35

[Gareth JonesParticipant @garethjones79649]

About a month ago my wife and I began preparing for the Manx MBC Manannan event and for the fun competition, we needed to operate two boats simultaneously and planned to do this with the two DX5E transmitters. We were taking 4 boats bound to one of these transmitters (known as the green one because the tops of the control sticks are painted green) and 1 boat bound to the pink transmitter (because it's sticks are painted pink.) The reason for painting the sticks was that in our club, DX5E transmitters used to be very popular and there were several occasions when members picked up the wrong one and failed to control their own boat, with amusing if not damaging consequences. Hence, along with several other club members we personalised our transmitters.

On practicing for the fun competition the night before we left for the Isle of Man, the receiver in the boat operated by the green transmitter failed to link. After repeated switching on and off and rebinding I eventually got the receiver to link but a short time after putting the boat in the water the failsafe operated and the boat reversed at high speed into the pond side. Fortunately it was a robust model (a Springer tug) and if you have seen the Manx MBC fun competition you would know why a robust model is required. This problem recurred on the next trial but it was too late to do any further investigation. In the Isle of Man the problem recurred after a period of satisfactory operation and, at the end of my entry in the steering competition, my Mountfleet steam drifter embarrassingly set off backwards at full speed and rammed the far side of the pond. Fortunately there was little damage as the boat was to be entered in the scale kit class the following day.

On the second day of the competition I found it was impossible to get my entry in the 'on the water scale' to link to the green transmitter and had to withdraw it. At the end of the day, with a lot of last minute switching and rebinding we got both our entries to work for the fun competition. The frustration these problems caused led me to start a more methodical investigation in our cottage the following day.

Next part, the investigation

[Gareth JonesParticipant @garethjones79649]

By now I was convinced there was a problem with the green transmitter so I brought all four models linked to it, into the cottage. The transmitter was switched on and all 4 models switched on, one after the other. After a bit of messing around I had all four models linked and operating satisfactorily, simultaneously. I wandered around the room, pointing the transmitter aerial in different directions – no problems. I turned each of the models off and back on and they linked, immediately or after a couple of seconds. I repeated this process turning multiple models off and back on – no problems.

I turned the transmitter off, all four models ran at full speed in reverse, the default failsafe was obviously set. I turned the transmitter back on, nothing happened. I repeated this and all four models linked again and worked satisfactorily. I went through this process several times, enough to convince me that the receivers were definitely not becoming 'unbound', just failing to link when the transmitter was turned back on.

I then embarked on a bit of internet research and made the first breakthrough, when I found an old PDF of the transmitter/receiver binding instructions.

Next part the first breakthrough.

[Gareth JonesParticipant @garethjones79649]

I have been using Spektrum equipment for about 8 years, have carried out the binding process, probably hundreds of time, I did not need to read the instructions each time I did it. You fit a bind plug in the receiver, power it up, hold the trainer switch up, turn on the transmitter power, wait till the light is solid in the receiver and then let go of the trainer switch – its bound. You can then remove the bind plug from the receiver. However, on reading this old PDF file I saw a note at the bottom of the binding instructions it said:-

NOTE Continuing to hold the trainer switch during the binding process will prevent failsafe positions being learned by the receiver.

Bloody hell I thought, all these years I have been doing it wrong. As soon as the lights start flashing on the transmitter you should release the trainer switch.

Armed with this knowledge I went back and rebound all four models by the proper process, with the throttle in the mid, off position. I removed the bind plug from the receiver and then turned the transmitter off. In every case the failsafe now worked correctly and the motor stopped. However I still had the problem that when I turned the transmitter back on, the receiver might or might not link. Well at least I had fixed one problem, so, after I had rebound the pink transmitter and its receiver correctly, I started to investigate the failure to link. A bit more internet investigation of this problem gave me a clue as to where the problem might lie.

Next – the ON OFF switch

[Charles OatesParticipant @charlesoates31738]

Blimey,this is more fun than the cxxx on the TV! Keep it coming.

Chas

[Gareth JonesParticipant @garethjones79649]

I found a thread on another well known model boating forum where someone had experienced similar transmitter/receiver linking problems and identified the fault as the main on/off switch for the transmitter. Apparently it could fail in such a way that the transmitter battery indicator lights illuminate but the transmitter itself is not powered up. This seemed plausible so I embarked on another series of tests.

I bound one of the 'green' receivers to the pink transmitter, by the correct process – it powered up and the indicator light in the receiver was solid within a couple of seconds. I then turned the transmitter off and back on – it linked. I repeated this process 25 times holding the transmitter in various attitudes and positions around the room and the receiver never failed to link.

I then rebound the same receiver back to the green transmitter and repeated the exercise, switching that transmitter of and on 25 times. On 9 occasions the receiver failed to link after waiting at least a minute to give it a chance. This seemed to confirm there was a fault in the green transmitter and the switch was a possible cause.

If the fault lay in the switch then maybe the sliding action could give a clue so I switched the transmitter back on several times, until the receiver again failed to link. I then pushed the sliding off/on switch slightly back to the off position and the receiver linked. I repeated this test about 3 or four times and each time it seemed moving the power switch just slightly back from the fully on position seemed to be enough to establish a link. However after that the transmitter did not fail to link when switching it on normally so this test again pointed to the switch being faulty but was not conclusive.

Further testing needed a multimeter and would have to wait till we returned home.

[Gareth JonesParticipant @garethjones79649]

After returning home, emptying the car, doing all the washing, cutting the grass and all the other post holiday jobs I took the back off the green transmitter and had a look inside. On the main circuit board there are three pairs of contacts where the power switch is soldered to the board. Using my trusty multimeter I measured the voltage on each terminal.

With the power switch off, the upper centre and right terminals were at 5.7 volts relative to the black battery earth terminal just below the switch. All the other terminals were at zero volts, as shown on the picture below.

With the switch in the on position the upper left and centre switch terminals were at 5.7 volts and the terminals immediately below these were at 3.2 volts as shown in the picture below.

I thought this might indicate a fault as I would not have expected any voltage drop across the switch terminals, although I am not an expert in wiggly amps. I therefore removed the back of the pink transmitter and did the same measurements on that and got the same results, apart from a slightly lower battery voltage at 5.6 volts. I tried to do the same on the DX6I transmitter but the back of the switch terminals were not accessible.

Using the green transmitter I switched it off and on several times with a receiver bound to it. The voltages on the switch terminals were always the same, even when the receiver failed to link. Pushing the switch slightly back towards the off position also had no effect on the contact voltages. This made me begin to doubt that it was the switch that was faulty so I pondered what to do next. I decided to remove the circuit board from the pink transmitter and remove and reconnect each of the multi pin connectors on the upper side, since the fault seems to be more likely the result of an intermittent connection failure rather than a solid hardware fault such as a burned out component. All the connectors seemed clean and making good contact and after refitting all the connectors the fault was still apparent and the green transmitter did not always link when first switched on. It appears to me that if I switch it off and on multiple times, the fault seems to diminish in frequency but if I leave it for a few hours or a day, the next time I switch it on it fails to link.

What next?

[Gareth JonesParticipant @garethjones79649]

I cant think of any more testing I can do to investigate the problem. I am intrigued why the voltage on the output side of the power switch is lower than on the input so if anyone has any knowledge on this aspect or a circuit diagram for the transmitter I would be interested to hear it.

For the time being, the green transmitter has been put away in the cupboard. It is 8 years old and I am not sure it is worth sending it away to be repaired now. We are pretty well committed to Spektrum since we have a lot of Spektrum receivers so we might well buy a replacement transmitter. Neither the DX5E nor DX6I are available in the from we have them so it will have to be another model with yet another operating protocol which might or might not be compatible with our old receivers.

I plan to write to the Spektrum service department and point them to this story and see whether they have any suggestions. If I have any feedback from them I will pass it on. This has been an interesting but at times frustrating exercise but then fault finding sometimes is. However my confidence in the Spektrum system has been largely restored now that I know the failsafe really does work as they describe, if you set it up properly. I have also learned a valuable lesson – when in doubt read the bloody instructions properly and follow them, not your own version of the process.

Gareth

[Dodgy Geezer 1Participant @dodgygeezer1]

Posted by Gareth Jones on 16/07/2017 07:58:45:

I cant think of any more testing I can do to investigate the problem. I am intrigued why the voltage on the output side of the power switch is lower than on the input so if anyone has any knowledge on this aspect or a circuit diagram for the transmitter I would be interested to hear it….

Without any knowledge of the circuit this must be a wild guess – but 5.7v makes me think of logic circuitry, while 3.2v makes me think of an LED feed. So the switch could be passing power to the main circuit and the LEDs separately? Which would match the story about the LEDs working while the main circuit didn't (if only the 5.7v contact inside the switch were to fail)….

[Paul TParticipant @pault84577]

Hello Gareth

​I'm happier in the knowledge that its not just me as I was really starting to think I was finally loosing my marbles.

As most readers will know I have recently suffered problems with binding a Spektrum DX7 to cloned products, I solved one of the problems with a lump hammer the answer to my other problem arrived yesterday….a brand new Spectrum receiver.

Tomorrow is the big day when I 'do the deed' and try to bind the two together but before I do I will be taking note of all advice given on this subject.

So tomorrow is either a happy day or a big day for a meeting between the DX7 and the hammer.

Paul

[Gareth JonesParticipant @garethjones79649]

As an update to this thread a query was sent to the Spektrum service department in Germany a couple of weeks ago but I have not had any response yet.

Since we are pretty well committed to Spektrum because of the number of receivers we have installed in various yachts and boats I decided to order a new DX6E transmitter, which arrived last weekend. It seems to work well and has a number of useful features in that the controls sticks can be configured to Mode 1 or 2, free moving, ratchet or spring centred without needing to remove the back of the transmitter and mess about trying to fit or remove small springs. It also has a large number of 'spare' switches which can be assigned to different channels. For example you could have the throttle on a switch which gave you two positions, full ahead or stopped. (I think some people sail like that anyway.)

It does have one drawback, which I was aware of before buying it, in that it will only bind to DSMX standard receivers. It will NOT bind to DSM2 or the marine MR200 receivers. Since we have a mixture of all three of these standard receivers I have just been through a major swapping and rebinding exercise to allocate boats and yachts to particular transmitters. Noticeably, since the 'green' transmitter has been excommunicated to the back of a cupboard, every receiver bound quickly to its allocated transmitter at the first attempt. I now hope and pray that my very old DX5E 'pink' transmitter and somewhat younger DX6i keep going or we could be stuck with about a dozen incompatible DSM2 and MR200 receivers.

Paul,

How did the meeting between your DX7 and new receiver pan out?

Gareth

Edited By Gareth Jones on 02/08/2017 21:27:10

[Author]

Posts