JR 9x 2.4 failsafe Question
03-24-2015, 07:28 PM
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JR 9x 2.4 failsafe Question
I have a JR 9x 2.4 radio, had it for several years, never had the slightest problem, until the other day, I was flying a model with Retracts, had been up for 5mins or so, straight and level at the time, then the retracts cycled, they came down then went straight back up, I didnt notice anything else, it was a bit windy, I turned the model around and landed, everything worked fine,
when I thought about it, the wheels coming down could have meant it had gone into failsafe, my thoughts are most likely the Transmitter at fault, as of yet I have not given it another range test, I have flown the model several times previously, no problems noticed,
could it be a receiver problem, if it lost a signal, I have been in the game for quite a while, the Rx is a JR 921, it is soft mounted (Velcro) around the back of the wing, gas engine, electronic unit right up front, remote Rx is pointing at right angles to the main Rx. 2 battery packs for the Rx, 2 switches.
I have since used the Tx again, with a MUCH cheaper model, not a glitch. I have been using JR gear for over 20 years, I have about 10 of the JR 921ś so I am not in a position to buy a new JR transmitter now they have changed their system, very disapointed about that, so if I buy another Tx it will have to be a Spectrum,
any thoughts on the problem, I am not too keen on using this Tx with my good models, after all, $500+ for a new Tx compared to several thousand $$ for a model.
thanks, Oldtimer.
when I thought about it, the wheels coming down could have meant it had gone into failsafe, my thoughts are most likely the Transmitter at fault, as of yet I have not given it another range test, I have flown the model several times previously, no problems noticed,
could it be a receiver problem, if it lost a signal, I have been in the game for quite a while, the Rx is a JR 921, it is soft mounted (Velcro) around the back of the wing, gas engine, electronic unit right up front, remote Rx is pointing at right angles to the main Rx. 2 battery packs for the Rx, 2 switches.
I have since used the Tx again, with a MUCH cheaper model, not a glitch. I have been using JR gear for over 20 years, I have about 10 of the JR 921ś so I am not in a position to buy a new JR transmitter now they have changed their system, very disapointed about that, so if I buy another Tx it will have to be a Spectrum,
any thoughts on the problem, I am not too keen on using this Tx with my good models, after all, $500+ for a new Tx compared to several thousand $$ for a model.
thanks, Oldtimer.
03-25-2015, 07:53 AM
#2
Any flashing lights on the rx when you landed? Assuming and I REALLY hate doing that, your bind was done with the gear down which would mean that on a power cycle the rx would return all servos to the position they were in when bound to the tx. Then as the rx links with the tx, the servos would go to the position dictated by the tx e.g. power to rx goes off, when power comes back on the gear would extend, when the rx links back up with the tx, the gear would retract again.
This is especially possible if you do not have the upgraded rx's with the "Quick Connect" feature.
Now if the Quick Connect is not present in the rx's firmware, you wouldn't get the flashing light power brownout indication. IF these are updated or newer rx's with that feature and you had no flashing lights on landing, it would seem to be an RF failure causing the rx to go into it's failsafe mode as you speculated.
This is especially possible if you do not have the upgraded rx's with the "Quick Connect" feature.
Now if the Quick Connect is not present in the rx's firmware, you wouldn't get the flashing light power brownout indication. IF these are updated or newer rx's with that feature and you had no flashing lights on landing, it would seem to be an RF failure causing the rx to go into it's failsafe mode as you speculated.
03-25-2015, 11:18 AM
#3
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You didn’t mention what type of retracts you were using, electric or mechanical/servo-driven. If it is servo driven, which servo? Nor did you mention what type of failsafe you were using. Here is my take if using a servo with normal failsafe.
On the DSM equipment, the failsafe is a function set by the receiver and not the transmitter. The 921 receiver has two types of failsafe. The normal Smart failsafe is where the binding connector is left in while pressing the bind button on the transmitter. The Preset failsafe occurs when the binding connector is removed before pressing the transmitter bind button. With Smart failsafe all channels are hold last position except the throttle which goes to the preset position.
So if you weren’t using the Preset failsafe, the gear wouldn’t have come down due to lost of RF signal. A power interruption may have caused it. If the servo is a JR retract NES703, a power interruption would cause the servo (assuming it was in the extended position at the time of binding) to extend briefly when power is restored. The movement is so small you probably wouldn’t have noticed it. However if you are using a standard servo, it can go to full extended position, hold it briefly and then retract. This is not the same as failsafe. If the RF rather than the power is interrupted when using Smart failsafe, there is no movement.
Examine your airborne power system first.
However, if you are using the Preset failsafe, then we're back to the possibility of an RF link failure.
Allan
On the DSM equipment, the failsafe is a function set by the receiver and not the transmitter. The 921 receiver has two types of failsafe. The normal Smart failsafe is where the binding connector is left in while pressing the bind button on the transmitter. The Preset failsafe occurs when the binding connector is removed before pressing the transmitter bind button. With Smart failsafe all channels are hold last position except the throttle which goes to the preset position.
So if you weren’t using the Preset failsafe, the gear wouldn’t have come down due to lost of RF signal. A power interruption may have caused it. If the servo is a JR retract NES703, a power interruption would cause the servo (assuming it was in the extended position at the time of binding) to extend briefly when power is restored. The movement is so small you probably wouldn’t have noticed it. However if you are using a standard servo, it can go to full extended position, hold it briefly and then retract. This is not the same as failsafe. If the RF rather than the power is interrupted when using Smart failsafe, there is no movement.
Examine your airborne power system first.
However, if you are using the Preset failsafe, then we're back to the possibility of an RF link failure.
Allan
Last edited by AWorrest; 03-25-2015 at 04:51 PM. Reason: Added last sentence
03-25-2015, 09:17 PM
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hello, thanks for the replies,
I didnt realise how much I didnt know about just binding a radio. have been doing a lot of reading up today,
it turns out I havent been doing a Preset Failsafe, I normally just leave the bind plug in and have the sticks and switches set then do the bind bit.
the model is an ESM Spitfire, petrol engine, air retracts, I have always bound my models with the wheels down, throttle at idle, with the bind plug in for the bind process.
this particular JR 921x Rx has always been a bit funny to bind, I have to hold the Tx very close to the Rx to get it to bind. I have done range checks but I cant remember when, I know everything worked,
this flight in question I did not check to see if the lights were flashing after I landed, It wasnt until later that I started to think about what it might have been. I am running 2 battery packs, both 5 cell Nimh, one into the battery port, the other into the Bind port, seperate switches of course, a seperate battery and switch for the engine.
the plan is to remove the Rx and have a good look at it and all the leads and connections will be pulled out and refitted. then pack the Rx in foam. then do a Preset Failsafe bind.
thanks, Oldtimer
I didnt realise how much I didnt know about just binding a radio. have been doing a lot of reading up today,
it turns out I havent been doing a Preset Failsafe, I normally just leave the bind plug in and have the sticks and switches set then do the bind bit.
the model is an ESM Spitfire, petrol engine, air retracts, I have always bound my models with the wheels down, throttle at idle, with the bind plug in for the bind process.
this particular JR 921x Rx has always been a bit funny to bind, I have to hold the Tx very close to the Rx to get it to bind. I have done range checks but I cant remember when, I know everything worked,
this flight in question I did not check to see if the lights were flashing after I landed, It wasnt until later that I started to think about what it might have been. I am running 2 battery packs, both 5 cell Nimh, one into the battery port, the other into the Bind port, seperate switches of course, a seperate battery and switch for the engine.
the plan is to remove the Rx and have a good look at it and all the leads and connections will be pulled out and refitted. then pack the Rx in foam. then do a Preset Failsafe bind.
thanks, Oldtimer
03-26-2015, 10:31 AM
#5
My Feedback: (5)
For normal powered planes, the Smart Failsafe you have been using is preferable to Preset. When you are approaching the limits of you radio’s range, the signal strength will fluctuate. This will cause a blip in the motor/engine, letting you know you getting too far away without causing a major change in the aircraft flight path.
Preset failsafe is more applicable for sailplanes. They are designed to fly hands-off with no motor. If they have a motor, the JR programming places it on some channel other than the first where Smart Failsafe has its only preset setting. Smart failsafe on these aircraft will not give you a recognizable warning and when the failsafe kicks in solidly, the plane becomes a flyaway.
It is difficult to explain how you may have had a power interruption when using dual batteries and switches. Yet with bench testing that is the only way I could cause the retracts to extend unintentionally when using Smart failsafe. The problem could be with the retracts. If you had a range problem using Smart failsafe, the engine should have gone to its preset position and all the control surfaces as well as the retracts should have froze in place momentarily.
Allan
Preset failsafe is more applicable for sailplanes. They are designed to fly hands-off with no motor. If they have a motor, the JR programming places it on some channel other than the first where Smart Failsafe has its only preset setting. Smart failsafe on these aircraft will not give you a recognizable warning and when the failsafe kicks in solidly, the plane becomes a flyaway.
It is difficult to explain how you may have had a power interruption when using dual batteries and switches. Yet with bench testing that is the only way I could cause the retracts to extend unintentionally when using Smart failsafe. The problem could be with the retracts. If you had a range problem using Smart failsafe, the engine should have gone to its preset position and all the control surfaces as well as the retracts should have froze in place momentarily.
Allan
Last edited by AWorrest; 03-26-2015 at 10:46 AM.
03-26-2015, 11:58 PM
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hello Allan,
many thanks for the info, today I have removed the Rx, pulled it apart and gave it a light blow out with compressed air, had a good look over it with a magnifiying glass, put it all back together, plugged all the leads back in, refitted the Rx, I did a slight mod to the model, (cut a slot just behind the pilot) now I can see the lights on the Rx, same with the remote, have also fitted some air line over the antennas, to keep them reasonably straight. I have given it another Smart Failsafe Bind, (left the Bind Plug in) then I had a good play with it, turned off the Tx, turned it back on, with switches and controls in different position, if I turn off the Rx then back on it kicks in almost straight away, if I turn off the Tx it takes longer to kick back in. I tried both Tx and Rx several times, the throttle would return to idle, the retracts didnt cycle at any time. I have a Spectrum Flight Log, so I will do some checks for the next couple of flights. Plus a good range check on the ground before I fly it again.
I am using Carbon Fibre push rods on the elevators, the main Rx is in between them, about 1 inch away from them, part of the side antenna is within 1/2 an inch of one of the rods,
thanks, Oldtimer
many thanks for the info, today I have removed the Rx, pulled it apart and gave it a light blow out with compressed air, had a good look over it with a magnifiying glass, put it all back together, plugged all the leads back in, refitted the Rx, I did a slight mod to the model, (cut a slot just behind the pilot) now I can see the lights on the Rx, same with the remote, have also fitted some air line over the antennas, to keep them reasonably straight. I have given it another Smart Failsafe Bind, (left the Bind Plug in) then I had a good play with it, turned off the Tx, turned it back on, with switches and controls in different position, if I turn off the Rx then back on it kicks in almost straight away, if I turn off the Tx it takes longer to kick back in. I tried both Tx and Rx several times, the throttle would return to idle, the retracts didnt cycle at any time. I have a Spectrum Flight Log, so I will do some checks for the next couple of flights. Plus a good range check on the ground before I fly it again.
I am using Carbon Fibre push rods on the elevators, the main Rx is in between them, about 1 inch away from them, part of the side antenna is within 1/2 an inch of one of the rods,
thanks, Oldtimer
04-11-2015, 12:50 AM
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G´day all,
thanks for the help, I decided to buy a new Spectrum 9x Transmitter and a couple of new Receivers, upgraded the model in question and flew it, no problems, the new Tx is easier to use than the JR 9x,
one of the things I remember is there have been a couple of occasions that I have noticed condensation on the inside of the screen when I take it out of the Tx case. might have to find some drying agent to put in with the radios, it is NOT humid where I live, but can be on the cool side.
Oldtimer.
thanks for the help, I decided to buy a new Spectrum 9x Transmitter and a couple of new Receivers, upgraded the model in question and flew it, no problems, the new Tx is easier to use than the JR 9x,
one of the things I remember is there have been a couple of occasions that I have noticed condensation on the inside of the screen when I take it out of the Tx case. might have to find some drying agent to put in with the radios, it is NOT humid where I live, but can be on the cool side.
Oldtimer.
