How do you adjust the idle setting on the JR XP662? I cannot get the idle trim to work if I have the throttle pulled all the way back. When I move the digital trim with the throttle all the way back nothing happens........

If I move the throttle up 2 clicks then the Throttle trim adjusts my idle setting. But, I have to be about 2 clicks up from all the way back. The bad thing with this however is that if when you pull the throttle back to idle if you go just 1 click too far the throttle pulls all the way back, taking out ALL of the trim I had put in, as if I had hit the throttle cutoff button.

At first I thought I could fly like that but I found today that it is extremely difficult to pull the throttle back to this precision idle stick setting when you cannot hear your plane all that well. I inadvertantly caused 2 dead stick landings trying to bring the power back to idle.

Am I missing something here? Or is this how this feature is intended to be used?

I have set the Travel Limits for both the High and Low end of the throttle with the trim and Sub Trim at zero. With these set I pull the throttle back to idle and try to adjust my throttle trim and get nothing.

Any help is greatly appreciated as I am contemplating sending this radio back.

Sounds like you have to much throttle movement. Watch the carb as you move the throttle back to idle. Does it close off before the stick is all the way back? Also watch the servo arm. If it goes to far forward (or back) it might move in a lateral plane, and not actually push the push rod forward of backwards, but will move it sideways. Thats my guess

When I pull the Stick back and observe the Carb. The Carb closes completely with the stick all the way back.

I have set the Travel limit to prevent over travel in both directions.

The radio acts like when you pull the stick all the way back that it is a cutoff function. Up 2 clicks and the trim works and you can adjust the idle..... pull it back those 2 clicks and it moves exactly the same as if you hit the Cutoff switch (Pulls the Carb all the way closed).

Sounds like you have too much travel set at low throttle. The carb should not close all the way when the stick is pulled all the way back.

Even when I move the End point limit further up (Carb slightly open) the radio still exhibits this behavior. Digi-Trim has no effect on the throttle unless I advance the throttle 2 clicks.

In addition to that the throttle cutoff switch only pulls the throttle closed to whatever end point you have set for it. So, if you have the carb slightly cracked the cutoff will only pull the carb to the slightly cracked position.

I appreciate the response....... if you have any more ideas I am all ears.......

I beleive this to be a classic case of poor mechanical installation and over reliance on electronic end point adjustment. There is nothing wrong with your radio. This does not allow the servo far enough down in the range where the the throttle trim will function.

The mechanical advantage of the pushrod geometry is way to much, The pushrod is connected to the servo output arm to far out and possibly the pushrod is not in the furthest hole out in the throttle arm. This forces the low end point to be so low that the trim is effectively bypassed.

Try first moving the pushrod to a hole closer to the servo and make sure it is in the farthest hole in the throttle arm then open your high and low throttle endpoints up to 100%. and start over.

John

John, I will take a look at that again and verify if this is the case. The only thing that doesn't add up is that if it were a case of the servo not being far enough down in the range then the trim shouldn't work when I move it further away from the low point by 2 clicks, the way that it does........

But hey, it's worth a look.........

Right now I have the throttle pushrod in the furthest hole in the throttle arm, and Servo both. As a result I had to set the End points down at about 50% each high and low to prevent over travel. I can change the linkage around on the servo end to get the End points closer to the 100% mark.

I'll post wether or not this helps.

Thanks for your suggestion,
Rich

Dang John, talk about hitting the nail right on the head!

Rich,

You need to start over like John had mentioned.

Use the same hole you're using on the throttle arm. Use the middle hole on the servo arm. You want the throttle pushrods movement to be as linear as possible. Set the servo arm back about 60 degrees from perpendicular to the throttle pushrod. Set your throttle settings on the radio to the defaults. Now this is all you have to do-

Move your throttle stick ALL THE WAY down and put your throttle trim ALL THE WAY down. Now close the carburator ALL THE WAY shut. Tighten your easy connector (I hope that's what you're using) right there with the throttle down and the carb closed.

DONE!

If for some reason it moves a little too far at full throttle, THEN use your end point adjustments...You shouldn't have to though...

I used a JR 662 radio for about a year and I am familiar with the problem that you are talking about. It took me a while to figure it out the first time. The secret is to make sure that you are not using too much sub-trim or travel adj to compensate for poor setup at the servos.

Try the following:

Set the throttle sub-trim to 0 and the travel adjustments at 100%, and make sure the digital trim is at "0". Note- you will have to push the throttle stick forward to set the "high" travel adj and pull it back to idle to set the "low" travel adj.

Now position the stick at center. Make sure that the throttle is approx 1/2 open and the servo arm is perpendicular to the connector rod. This is very important with the 662! You may have to pull the servo arm off and reposition it, and adjust the clevises to get things right.

Now, with the travels still set at 100%, find the holes in the throttle and servo arms that get you nearest to full open and full closed when you move the stick back and forth.

Finally, once all the above has been done, adjust the travels in the radio as needed. To do this push the stick all the way forward and adjust the "high" travel so that the throttle opens fully. Then pull the stick all the way back and adjust the "low" travel so that the throttle is at normal idle position.

After doing the above you should find that the trim and kill button work properly. The last step is to fire off the motor and test. You may have to adjust the "low" travel a bit to get the kill button to stop the motor. And use the digital trim to get the idle where you want it. But do not use the sub-trim to try to compensate!

I upgraded to an 8103 two months ago and I'm still getting used to the manual throttle trim. I actually like th JR digital throttle trim on the 662, but I think that it gets a bad name because many people have problems setting it up correctly.

Ok, I didn't think my throttle linkage was set up poorly but what the hell, it's an easy thing to try........

here's what I did.........

1) Set Digi-Trim to zero.
2) Set Sub Trim to zero.
3) Unhooked Throttle Linkage.
4) Set high and low Travel to 100%
5) Connected Linkage at the Carb to lowest hole (Most throw)
6) Connected Linkage at the Servo to second hole out from the servo and left the pushrod loose for adjustment.
7) Powered up the Radio and pulled the Throttle back all the way to what would be idle.
8) Adjusted the throttle pushrod until the Carb was closed and tightened the connector on the pushrod.
9) Move throttle all the way forward, throttle movement stops just as the carb reaches full open. No High Travel adjustment necessary....... left at 100%.
10) Move throttle all the way back, Throttle movement stops just as the carb closes off. No Travel Adjustment necessary....... left at 100%
11) Move digital trim "Up" to "40" attempt adjusting the idle setting and the throttle doesn't move at all. The Adjustment does nothing.
12) Move the Gimbal 2 clicks off of idle and the throttle jumps to about 1/4 open.
13) Adjust Trims with Gimble in this position and the trims open and close the Carb.
14) Set Trim back to 40 (Carb 1/4) open, hit throttle Kill Switch and the Throttle pulls all the way back closing the Carb.
15) Release throttle Kill and Carb opens back to 1/4 open.
16) Pull throttle Gimbal back the 2 clicks I had put in, to idle and the throttle pulls the carb all the way closed. EXACTLY as if I had hit the Throttle Cut off switch. The throttle does not jump like this when going from zero to plus 2 clicks if I remove all of the Trim I had put in, but rather moves a small amount very smoothly.

I am highly confident now that my linkage for the throttle is accurate...... given that I have 100% travel in both directions and get perfect throttle movement but I still have the same problem.

Any other ideas?

Rich

Yes

you defeated moving the rod in at the servo arm one hole by moving the pushrod out at the throttle for not much net change and there is still to much throw. To increase mechancal advantage at the servo you move the pushrod further from the servo And at the throttle you move it closer to the carb. To decrease mechanical advantage you put the rod closer to the servo and at the carb move it further from the carb.

Consider trying this:

Attach the pushrod at the servo to the middle hole.
Attach the pushrod at the carb to the hole farthest out.
Set throttle subtrim to %0
Set Hi and Lo endpoints to %100
Turn Tx and Rx on
Pull throttle down all the way
Push throttle trim switch down (the same direction you moved the throttle) and hold untill it stops beeping.
Now adjust the clevis or easy/just untill throttle barrel is just completely closed
Open the throttle all the way up, It should be fairly close and can be adjusted with small amounts of high endpoint.
Close throttle all the way down and it should return to just completely closed
Push throttle trim switch 'up'(same direction as full throttle) and hold a few seconds and the throttle barrel will open to a cracked position that can be set with subtrim.

John

I wish I still had the 662 radio so I could try exactly what you did step for step! I'm not sure if you have a bad radio or if you still have a setup problem.

The one thing that you did different than I recommended is your step #10. If you look at my earlier note you will see that I said to adjust the low travel (with the trim set to 0) so that the throttle is at the "normal" idle postion with the stick pulled all the way back. It should not be set so that the carb fully closes as you described.

Give this a try and let me know how it goes. I think it could be an important difference!

I think that John and I are saying the same thing only he is suggesting that you make up the difference with the clevis adjustment and I am suggesting that you do it with the %travel.

If one way doesn't work then try the other and see what happens.

Yes Build-n-flyer thats pretty much it and I suspect that JUtah still just had to much mechanical advantage on his second attempt.

JUtah
If you are still having problems try to get someone familiar with computer radio installation to double check you before sending the radio back. Throttle installations has always been a source of frustration for folks but with a computer radio it can be easier with the right mechanics. I just helped a fellow yesterday with almost an identical problem and the real problem here turned out to be a far to flexable throttle rod that really complicated things.

John

Ok........... let me preface this by saying that I appreciate you guys taking the time to respond to this thread.

John.... I believe I have exactly what you are recommending. Perhaps I am just not explaining it very well. You said for me to
"
Attach the pushrod at the servo to the middle hole.
Attach the pushrod at the carb to the hole farthest out.
Set throttle subtrim to %0
Set Hi and Lo endpoints to %100
"
This is exactly where I have the pushrod connected. On the Servo it is the middle hole as you called it, or the Second hole from the Servo as I called it (3 holes on the servo arm). On the Carb I have it connected to what I called the "Lowest" hole or as you call it the "Farthest out".
I did set the Subtrim to 0%, and I do have the Endpoints at 100%. Now, with the linkage setup this way I get the throttle perfectly closed at idle and fully open at full throttle (No over travel) without adjusting the end points.

Build-n- flyer/John..... I will look at step 10 again and see what happens. If memory serves me correctly the Cutoff will only pull the throttle to wherever the Low Travel adjustment is set. So if I set the adjustment to say -80% (Carb partially open in the idle position) then the cutoff switch will not close it and shut the motor down.

I will however look at it again.

Thank you both once again for your time.
Rich