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

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.

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?

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