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JR 8103DT FM with Glitching/Chattering Problems

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Old 11-24-2002, 09:03 PM
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3dflyer
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Default JR 8103DT FM with Glitching/Chattering Problems

I purchased a new JR 8103DT FM radio on channel 60 about 1 month ago. I have flown with the radio in a 4 channel/5 servo aircraft with no problems. When installing the radio in my new Great Planes UCanDo3D, I am having some serious glitching/chattering issues. The issues are intermittent and I cannot reproduce them on demand. Sometimes the radio appears to work fine and other times the radio goes crazy. This model has 2 servos for the elevator and one for the rudder mounted in the tail end of the fuselage. I am using heavy duty gold JR externsions for the three servos that are 24 inches in length. With the 6 inch servo lead, the extensions are a total of approximately 32 inches each. All the servos are JR 537's and they are all brand new. When the glitching occurs, the throttle servo does not appear to glitch - only the servos in the tail end of fuselage. Could these long extensions cause issues with radio interference? With extensions of this length does anything special need to be done like filters? I have tried the NER-549x receiver that came with the radio and also an R700 with the same glitching/chattering, though the R700 appears to be a bit worse. HELP!
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Old 11-24-2002, 09:31 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

The extensions could be it. Try one of two things. Put a filter on the extensions or tie a knot in each one.
later daveo
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Old 11-24-2002, 09:58 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

If a filter is to be installed what and where should it be installed?
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Old 11-25-2002, 12:44 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

From your description, it sounds like your problem is the extensions or connections in the extensions. If so a filter will be of little or no help. If you can, use at least 22 gauge wire on the extensions with good gold plated connectors or better yet, no connectors at all--direct soldering. Only the postitive and negative leads need be the heavier gage wire as little current is on the signal wire. To see if this is really your problem, power the aft servos with a seperate battery (break the positive lead between the reciever and servo and tie in an external battery between the positive and negative leads at the servo end). If you do this, I'm quite sure your glitches will dissappear.
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Old 11-26-2002, 09:33 AM
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Default JR 8103DT FM with Glitching/Chattering Problems

Thanks for input Rodney. I contacted JR to see what they had to say about my problem. The person I spoke to said I needed to purchase a PCM-S receiver to fix the issue. I was told that 3 32" extensions would pick up electrical noise and that's what's causing my glitching. I am now worried that there may be something wrong with my receivers. I thought that FM narrow band receivers were quite tight. Is there an truth to this? I am confused!
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Old 11-26-2002, 12:30 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

You never said where your ANT. is routed. Is it touching any of these leads your talking about.
I"m not to sure the PCM reciever is the answer. It might be more imune to interferance but that dosn't fix your original problem . It only hides it. One other thing to check.All of those leads should be sepperated and zip
tied to the sides of the fuse. later daveo
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Old 11-26-2002, 12:41 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

PCM receivers are no more tolerant of interferance than PWM recievers although they will mask minor problems which can come back and bite you but good. If you have problems now, you need to find the cause and correct them before just going to PCM. As stated above, keep your antenna routed as far from the other wiring as possible.
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Old 11-27-2002, 02:01 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

OK, here is where I am to date. I pulled everything apart and inspected the extensions and servos. I could not find anything wrong. All the wiring is new and looks perfect. I plugged the radio in on the bench and layed everything out as it is when installed in the fuselage. I wiggled every single inch of all the wiring and connectors, atpped the servos against the bench - everthing I could think of. I could not get the glitches to occur. I also went ahead and borrowed a newer never crashed JR 649 PCM-S receiver from a buddy. I used a brand new crystal and reinstalled everything. Things were great until I went out earlier this afternoon to run in the motor. The glitching came back - even with a PCM receiver!

I am dumbfounded and just do not know what to do. I think I am going to buy 3 new extensions and 3 new servos and try again. Since I cannot duplicate this at issue at will, it makes finding the issue next to impossible.

Any other ideas? I am positive there is nothing wrong with the radio. I have tried 3 receivers now and they all do the same thing. I am convince the issue lies in the extensions or servos. Perhaps there is a bum servo that is emitting radio noise or something.

I also made sure that the antenna is not touching anything - it wasn't before and still is not. The antenna does run parrallel to the extension on the outside of the fuselage, but I do not think this is the issue. I had the glitching occur previously and swapped receivers as it was happening. The 2nd receiver had the antenna going out of the fuselage towards the motor and was nowhere near the extensions.

HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP!

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Old 11-27-2002, 03:41 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

I had a JR PCM go into failsafe 4 times. There seemed to be know pattern when it would do it. I changed
servos one at a time till it stopped. Turned out to be the throttle servo. Mine would not do it on the ground
so your better off than I was. If you are going to change servos, do it one at a time so you can find the bad one.
It still wouldn't hurt to put a loop in each of your extensions. Even if thats not the problem.
later daveo
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Old 11-28-2002, 02:52 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

I went ahead and purchased 3 Expert 48" extensions with filters yesterday. Last night I was playing around with the receiver and it started glitching. I swapped one of the regular 24" extension for a new one with a filter. To my suprise, the glitching stopped. I also plugged the servo directly into the receiver without any extension and the glitching stopped. I was glad to finally make some progress.

One thing that came to me was that I could not duplicate the issue in my house. It never came up during setup of the control surfaces. As a test, I put the receiver, extensions, and servos out on my cold garage floor. When I came back 45 minutes later and powered them up, they glitched. I think there may be something going on with temperature. It has been 30-40 where I live over the course of finding this issue. Does the cold have adverse effects on receivers and servos? How cold is too cold?
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Old 11-28-2002, 08:13 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

sometimes the switch causes a glitching when the engine in running because the plates that make contact ar vibrating. on...off...on.off real fast. battery may also have a loose weld tab. From all that you've tried that all thats left. I have a 123" bird and the ail/ flap servos only have the amps by jr. no problems. Also have an f-15 with soldered leads to ail/elv seros 36-48"? long and have had no problems.
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Old 11-29-2002, 02:50 AM
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Default JR 8103DT FM with Glitching/Chattering Problems

Try this, with the engine running, have someone hold the plane for you while you stand 50-75 feet away. Have them turn the airplane in increments of 45 degrees, and see if you can reproduce it. If you can, it is a problem with where your antenna is mounted. I would also change my switch like b17flyer said. I almost lost my WM Mustang when my switch went sour.
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Old 12-06-2002, 02:56 PM
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Default JR 8103DT FM with Glitching/Chattering Problems

Sometimes, servo cables picks up interference signals of external origin.

This problem only occours if the external signal is very strong and/or close.

Twisting the servo cable might help, filters also, best thing would be shielding the servo cable, maybe with alu-tape and connect this shield to the "-" (ground) of the battery or "-" on the reciver. The shield should only be connected to ground at one end.

The latter method is used on sensitive meashurement equipment to minimize interference.

Servo-malfunction is often mistaken for reciver glitches, I have been a victim of that so be aware for a while, until you are shure you found the problem.

Naughty servos can send back evil signals that affects all the other channels.

You wrote that the throttle servo operated OK, that makes my first suggestion more credible.

Long cables picks up interference easier than short ones.

Just my thoughts,
Bo
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