snurckle

I have a JR 9303 (2.4Ghz) Radio, and am using the 9 ch receiver that came with it. I have a micro servo that I am using to control a pneumatic retract valve.

When I apply power to the receiver the servo goes -45 degrees, and the returns to the Gear down position. Doesn't matter if the gear is up or down, it will always go to the "servo Power On" position, and then to the Gear Down position.

A couple of problems - The valve on the retracts only moves so far. If I have the gear in the down position, it will automatically move it to the up position. I'm trying to get the retracts set up.

How do I keep the gear servo from moving at all on power on. If anything, it should go to the down position, and not 45 deg past up, and then to the down position. I've attached a quick diagram, to show what's occuring. Not much, but should help.

codimasta

My Feedback: (89)

[8D]Re-Bind the receiver with the Servo Arm dis-connected....Wheel down position.(manually move the air switch)..connect the servo arm....then give wheel up..it should work correctly.

BuschBarber

My Feedback: (2)

If I am not mistaken, when you bind the Rx to the Tx, it also sets the Failsafe Condition for each channel. Normally, when you Bind, you connect the Bind Plug to the Rx or Switch Harness Charge Jack, the lights on the Rx Blink, Turn on the Tx with the Bind Button held, the Lights on the Rx go out and come back on Solid. This is Failsafe Hold, where all channels Hold their positions, during a Failsafe event, except the Throttle goes to Idle.

Follow the procedure for Binding to Achieve Failsafe Preset, where you move all the Sticks, Knobs, and Switches to Position the servos where you want them to be during a Failsafe event. When your radio goes into Failsafe, the servos will move to the Preset positions.

I believe the Bind procedure for Failsafe Preset involves Removing the Bind Plug after the Rx lights Blink, but Before you turn on the Tx with the Bind Button held.

When I first bought a Spektrum Module for my XP9303, I had a plane with Retracts and wanted the Failsafe Preset to be Gear Up. I did not realize there were two procedures for Binding. My Gear would always Cycle when I turned on the Tx and Rx.

airbusdrvr

BuschBarber is correct. This is a condition where after you have the airplane setup, you need to rebind the transmitter and receiver with the controls in their desired position-in your case chan 5 in the gear down position. That should solve your problem, at least as I understand your problem.

BarracudaHockey

My Feedback: (11)

Yep, but you have to not only rebind but remove the bind plug after the reciever lights flash but before turning on the transmitter with the bind button pushed.

airbusdrvr

I think what he wants if a Fail Safe bind as described on page G-21 of the manual(I hope he has read it). It states the bind plug is left in until after the receiever is locked in to the transmitter. Whatever he needs , if he will read page G-21, as Inspector Clouseau would say, the problem is "Solve Ed."

snurckle

All:
I appreciate the tips, I really do. I too thought it might have been a case of a bad preset fail-safe. That's not the case.

I have read page G-20, and G-26, and the pages in between. G-26 was 'tips' and FAQ's, but didn't find too much relevance.

So, this is how the fail safe is programmed, just so it doesn't become a problem, and if I'm doing it wrong, perhaps somebody will steer me in the right direction.

1. RX OFF/TX OFF
2. Insert Bind Plug
3. RX ON
4. Verify blinking on RX, and placement of Servo in the fail-safe position.
5. Remove Bind Plug
6. Depress Bind button on back of TX, and turn it on. (hold down bind button during process)
7. I wait about 10-15 seconds, usually takes 5 or so for the RX to stop blinking and go steady lights.
8. Turn off TX
9. Turn off RX

Verify Binding-
10. Turn on RX (Servo goes to 10 o'clock position and returns to fail-safe of 12 o'clock)
11. Turn on TX (Servo doesn't move at all)

Verify Fail-Safe
12. Turn on RX (Servo goes to 10 o'clock and returns to fail safe of 12 o'clock)
13. Turn on TX (Servo Remains at 12 o'clock)
14. Flip gear switch (Servo moves to 2 o'clock)
15. Turn off TX (Servo moves to 12 o'clock)

Wala - when signal is lost, the servo moves to the 12 o'clock position, which is the Gear down, and fail-safe position. The problem is not with the fail-safe, nor is it with the binding. It's not with the travel adjustment. It is with the servo, and the servo is analog. My assumption is- Analog Servo's require travel for centering. This centering action can be damaging for the servo, when it's travel is limited by a hard limit.

I hope the process above shows that I did something wrong. That'd be easy to fix. If I didn't do anything wrong, and I did everything right (bind/setting failsafe) then how do I stop the excess travel on the servo, so that I don't damage it when I mount it permanently in the wing?

Oh BTW, I reversed the servo, so the picture in my original post has the 12 oclock as gear up, and it is now gear down. Either way, the position doesn't seem to matter, I could put the gear up/down anywhere, and the servo still goes to the 10 o'clock position when it is powered on.

snurckle

I set the travel adjust so that the gear down was at the 10 o'clock position, so that if it went to 10 o'clock it would only move to the down position.

Didn't help at all. The servo went to the 8 o'clock position, and returned to the 10 o'clock.

It seems- no matter what I do, it will travel 60 degrees past where it is supposed to, and return to the gear down position. The servo is a JR Sport 22SM.

Also, have some HS821's (Digital), no travel, but I need a submicro, so the HS821's don't help. It seems the analog servo's are much to be desired for applications where limits are set by hard stops.

BuschBarber

My Feedback: (2)

The Bind procedure you outlined is definitely the procedure to use for Failsafe Preset. Make sure all the Switches, Sticks, Levers, and Knobs are in the positions you want the servos to go to when there is a Failsafe event, and then Bind.

I have been advised, in the past, that except for Binding, you never want to turn on the Rx before the Tx as some people have lost their Bind and had to ReBind after turning on the Rx before the Tx. The manual seems to say otherwise.

airbusdrvr

Why don't you go to the bottom right of page G-21 and perform the "Programming SmartSafe" and see if that doesn't solve your problem. The SmartSafe and Fail-Safe are a bit different. I have a couple of retract planes with the X9303 using either the R921 or AR9000 receivers. I remember before finishing my setup one of the planes did as you say with the air valve. But after rebinding following airplane setup, the servo for the air valve stays in the down position.

airbusdrvr

What receiver are you using. I seem to remember that there were people having power up issues with analog servos driving to their end points when using maybe the R922 or whatever the Spektrum equivalent receiver might be.

BuschBarber

My Feedback: (2)

For me, it was the SmartSafe that caused my Retracts to cycle, when the Tx and Rx were turned on. It was the Failsafe Preset that stopped it from happening

Zeeb

My Feedback: (41)

I think airbusdrvr has hit the nail on the head here.

Unfortunately, there is a known issue with the 9 channel rx's running analog servos. Seems as though the rx generates a 700us pulse when first powered up and before it goes to it's bind/failsafe positions. Some guys are getting full travel deflections beyond the servo limits set in the tx, some are just getting minor movements. I don't know if one particular brand or model of servo does it worse than others, but I have one R921 in a model with digital servos everywhere but the choke and that is a Futaba analog. When first turned on, that choke servo goes to it's midrange closing the choke about half way, then back to open after the rx goes to it's bind/failsafe settings.

Re-binding after setup does not correct this problem. AFAIK, the only solution is to go with a digital servo. This problem has shown up on several forums and there's several threads about it over on FG if you want to go look. Sorry but the RCU server will not allow me to post a direct link....

snurckle

Thanks, these responses have been very helpful, and I'm sure several people are scratching their heads....even Bob at the LHS. The RX in question is a JR R921, and fits the bill for your post. I purchased a spektrum digital sub-micro servo today from my LHS, and brought it home. Plugged it in, and would you believe - it didn't travel at all. A little click-click, and it remained in the fail-safe (down position).

In conclusion, I appreciate the resonses, and believe the R921 isn't meant for analog servos when the travel is limited by hard limits. The digital servo corrected the problem, and the problem is solved.

Thanks again!!

airbusdrvr

As I told you, Inspector Clouseau said the case could be "sol =ved." Just look at rule #4, http://inspectorclouseau.com/rulesofspeech.html

skyriter

I take it that there is no firmware upgrade that Horizon (JR) can do to correct this. I have the same issue and it is only with the analogue servos. Digitals work fine

Bruce