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Unusual gear failure

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Martin McIntosh10/08/2018 11:55:09
2874 forum posts
1062 photos

I had a strange type of failure last Sunday, resulting in the loss of a model.

I decided to swap motors between a Dalotel (YS63) and my Jumbo Dancer which was a 1.4x Limbo Dancer (OS91FX) since the former was under powered. The JD tended to be used as a flying test bed and I have a number of Rx`s, mainly FrSky and Orange which need checking out in the air. The Dalo is on an Orange Rx615 with satellite using a JR DSX9, the other one with a similar Rx and JR PCM9X2 with an Orange module, both of which have been in use since they came on the market.

I should have twigged that there was something amiss since I had to re centre the control surface trims even though these had been set to neutral on the bench. A range check seemed to confirm that all was OK but on starting the YS found that the throttle was reversed. Strange. I took it up and as expected it was somewhat tail heavy due to the lighter motor but I calmed it down with some elevator trim and throttled back. Suddenly, from quite a height it put its nose straight down and refused to respond to any controls. The hard baked earth did nothing much good with the Rx knocked out of its case and one of the two LiFe packs squashed flat.

Back on the bench for the autopsy and of course everything worked fine including the squashed pack and Rx. I then noticed that the 9X2 was on the wrong model memory so nothing should be happening. I swapped the Rx for an Orange 6ch without satellite and the model match worked normally.

I then checked the 615Rx in the Dalo with the DSX9 and model match also worked normally so the problem must lie with using an Orange module and a 615Rx. It does not explain why the set up went failsafe though. I have very many Orange Rx`s which have been in use for many years and have never come across this problem before.

Peter Christy10/08/2018 12:33:04
1487 forum posts
From my phone, so brief! Didn't think module used model match. Uses ppm, so no way to transfer required data.

Nigel R10/08/2018 12:48:30
2930 forum posts
470 photos

My first thought is something amiss with the Orange TX module itself. Either and intermittent failure to transmit, or a transmit power problem. As above it cannot do model match if it is hung on the end of the PPM output from the PCM9X2. Pure speculation, but, the module is plugged in, is there a chance of physical damage or poor connection?

The satellite (I presume the big limbo dancer had a satellite?) would seem to reduce the chance of it being a receive side problem.

Did the YS survive?

Peter Christy10/08/2018 13:08:28
1487 forum posts
Also, did you reset failsafe after reversimg throttle?
Peter Christy10/08/2018 13:08:31
1487 forum posts
Also, did you reset failsafe after reversimg throttle?
Martin McIntosh10/08/2018 15:13:45
2874 forum posts
1062 photos

Peter, model match does work with the module on any kind of Orange, Spektrum or JR Rx, except apparently the Rx615.

And you are right, I forgot to re bind it and set the failsafe after reversing the throttle! If I had done so I would have noticed the incorrect memory. Therefore it could not have gone failsafe but the controls just stayed as they were. Still a mystery. Unlikely to have been a power failure since two packs were supplying a Failover switch with two power inputs to the Rx.

Nigel, yes, the YS thankfully only suffered a broken throttle arm.

The Tx module is fairly new and was used to fly another model as well, so no problem there.

My old module failed due to a broken antenna to pcb solder joint, so worth a bit of epoxy here. Not repairable because the lack of a load blew the RF output stage.

Peter Christy10/08/2018 16:46:28
1487 forum posts

OK, sat in front of a proper computer now! (I hate trying to type on a smart-phone!)

You've got me really puzzled now, Martin! I too have an Orange Tx module, which I use in a PCM-9 - the early one, not the -2. On that one, model match most certainly does NOT work. My Orange module is one of the later types, without the dip switches. The PCM-9 communicates with it via PPM, which has no way of communicating which model is selected.

I know that with the Taranis, if you use a Spektrum module out of a genuine Spektrum transmitter on a "bodge board", you can get model match to work, but that's because the Taranis can "speak" DSM-2.

If your PCM-9 is set to PPM to work with the module, it has no way of communicating any model information to the module. It could only possibly work if the transmitter was set to PCM, which is not compatible with DSM-2/X, as far as I am aware. In fact, I'm not sure that the PCM-9 ever had model match when used with its own PCM modules on 35 MHz - its a while since I used it like that! wink

I'd be fascinated to hear how you have the Tx set up!



Martin McIntosh10/08/2018 20:13:51
2874 forum posts
1062 photos

Pete, I am determined to go into this a little further even if only for peace of mind since I cannot get my head round why some Rx`s should respond to model match and others not. Will keep you posted.

What confuses me is that the older Orange 6ch Rx seems to work as expected. Will try some others when I can.

I have not as yet tried the FrSky X series Rx`s on that Tx but the D series definately do not have model match.

Paul Marsh10/08/2018 21:10:10
3648 forum posts
1018 photos

I've lost models with Orange, so that is your culprit. Load of rubbish, all my rx's I put under a hammer and smashed them all.

I give an example. Bought a new P-40 at a Swapmeet, never been flown and came with a Orange 7ch full range with sat. Did range check, but did have a Spektrum AR8000 rx in the bag and was going to use that. I had lost 2 models before with Orange rx's, but this had a sat as well.

Range check, ok. took off and as soon as it took off, lost control and came round and went straight it. I was mad, did range check again and was ok. I was kicking myself, I should've use the Spekky rx, but no, my new P40 was damaged, and bought another one and this time used the AR8000.

I've seen models go in, using Orange and advise against using them, unless shockie fliers at close range.

Martin McIntosh11/08/2018 00:20:51
2874 forum posts
1062 photos

I would not use Orange if I did not trust them. Even my 1/4 scale Stampe has had a 9ch in it from new.

My 72" Spit. inexplicably went in with a £120 JR Rx even after very many previously uneventful flights and my Lanc. went down at Greenacres last year with a similar Rx. (Two other models crashed at the same time). Both are still in use with no further problems.

My point is that it was a combination of Rx615/Orange module/wrong model memory but the reason is still a bit obscure.

The Spit. failure was almost identical in that all controls including full throttle in this case stayed where they were at the point where control was lost.

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