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Glitching problems with RX setup

Old 06-04-2007, 04:56 PM
  #1  
bert269
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Default Glitching problems with RX setup

Hi

I have a Futaba setup. My TX is the Futaba 7CAP (capable of both FM (PPM) and PCM)... I try to only use Dual Conversion RX's - but even then I get glitches - servos are twitching and motor stops, starts, run at low speed......Even when I'm the only one at the field.

I will not even mention "not using Dual conversion RXs" - that's a disaster. When I use PCM 1024 & Dual conversion RX's - everything is just fine - no glitches, no twitching servo's or low running motor -all by themselves....Error free.

What is the problem? Where is my interference coming from with FM RX's. Do I have a TX problem? I have tried several different RX's - all the same... As I said, I just use Dual conversion RX (with Dual Conversion crystals).

Please, anyone with advice?

Thanks
Bert
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Old 06-04-2007, 05:15 PM
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skiman762
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Well duel conversion doesn't say much blue arrow rx's are duel conversion and you can't give those things away I tried one once and had all the troubles your having
so what brand are you using ?
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Old 06-04-2007, 05:27 PM
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bert269
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As I said - my setups are Futaba, TX as well as RX's...Just Futaba - no other brands.

Thanks
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Old 06-04-2007, 05:38 PM
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adwb
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Originally Posted by bert269 View Post
Hi

I have a Futaba setup. My TX is the Futaba 7CAP (capable of both FM (PPM) and PCM)... I try to only use Dual Conversion RX's - but even then I get glitches - servos are twitching and motor stops, starts, run at low speed......Even when I'm the only one at the field.


Please, anyone with advice?

Thanks
Bert
Bert,
3 questions,
at what distance from the rx is the tx when this happens?
is it the same at other venues?
if you try a tx distance test with the tx antenna collapsed is ther a difference compaired to when it is extended?
Alistair
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Old 06-04-2007, 05:49 PM
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Bill G
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Default RX - ESC Interference

Until yesterday, the only gitching I've ever experienced is a Maxx flashing light system that causes throttle glitching. Interestingly, once the plane is 5 feet from the transmitter it stops, which is part of what ADWB was getting too. I'm not sure why this happens, but I'm sure their are reasons for it.
Bundling the extra length of the ESC lead minimized the problem. Bundling leads to remove excess length is probably the simplest thing you can do to avoid making "antennas".

Yesterday, I decided to move a receiver about 1" forward, to move weight up a bit. The plane has never been flown, but had tested fine before. When I tested the throttle, it was all over the place, and would then default to a mid-throttle setting and stay there. The receiver is an FMA5, which I believe has a last good signal holding.
The problem was that the receiver was moved too close to the ESCs, so I moved it back to where it was. Their are 2 CC25 ESCs, for this twin EDF. In the future, I'll make sure to keep them apart.
Along the lines of the problem I experienced, some of the brushed ESCs would allow you to change the gating frequency, to try to cure these problems.

Its easy to get sloppy with component location and wire routing, until you actually see these problems that other folks have firsthand. I've been pretty fortunate as of yet.
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Old 06-04-2007, 05:52 PM
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DickCorby
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It may have to do with the PPM/PCM modulation thing. If it is not set to the correct one for the receiver you are using, you will have problems.

When I changed over to the XPS spread Spectrum system, I had my Futaba 9C set to PCM for the receiver I was using, and the problem you describe is exactly what I was getting.

Then i actually read the directions for the XPS Module, and changed to PPM and lo and behold No more glitching
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Old 06-04-2007, 06:07 PM
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Charles, AC6WU
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Bert,

As a Ham Radio Operator and being in the retail hobby industry for almost 30 years and an active modeler since 1947, I might be able to offer some assistance.

Single or Dual conversion doesn't matter in this case. Your glitching is probably caused by one of two reasons:
One; Close proximity of your Rx to the ESC and/or servos. While using a Futaba Rx in a similar situation, I had to completly wrap the Rx with a bit of tin or aluminum foil to act as a RF barrier. Try it and see if the problem solves itself. Two; Although rare, the Rx can become overwhelmed by the strong signal while the Tx is close to it. That's as simple a fix as moving farther away from the Rx while transmitting.

I have experienced these problems in the past and the remedies above cured them. Good luck...

Best regards,
Charles, AC6WU
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Old 06-04-2007, 06:40 PM
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navy atc
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I had a very similar problem this weekend with more catastophic results. Ive got a HZ super cub gutted of all hz stock. Has a hiamxx 2025-4200 and eflite 25a esc with the spektrum 6 rx aboard(servos included) I have flown this as a seaplane and got it soaked, as a land plane and smacked it so hard face first into the ground that I knew it was toast, but it went right back aloft. Despite my fancy crashing ability..Nothing wrong.. Never once stopped for more time than it took to dry out the electronics,Prior to any power application until I was sure it was "bone" dry and I mean bone dry, then whoom. back aloft.I've been flying after these little tricks for more than a month w/no problems. Well this weekend I went to fire it up and my himaxx starting twitching back and forth in miniscule increments, clock and counter clockwise, nor more than maybe two teeath turns on the gearbox. Then smoke started to come from the himaxx, followed by the ESc. Well, back to the LHS for a new himaxx. Got that .Same issue.twitch twitch and even more sporadic twitch. Back again to the LHS for a new eflite ESC. Put that on. Got more sporadic twitching and she finally came alive and is working ok now. My question is this?? Could the lake water that got into my dx6 receiver have built up crud thats causing this intermittentcy.? And if so what would have been the reason it fried one himaxx and not the new one?. Do I have gremlins or what?? Natch the LHS
wants me to buy this that and then again something else. The little orange light comes on in the dx6 rx but sometimes a bit more slowly than Im accustomed to. Anybody got any advice? If you suspect lake water crud on the dx6 rx board, do you know how(aside from parting with another 60bucks to treat this anomaly, it could be fixed?? Any help would be greatly appreciated..
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Old 06-04-2007, 07:59 PM
  #9  
Charles, AC6WU
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Navy atc, You get a Rx wet and continue to abuse it by crashing knowing it is toast... why in the world would you put everyone at the flying site at risk and use it again? I hope your home owners insurance is paid up and if you belong to AMA, don't expect them to cover you. Water works in wonderous ways building "crud" on electronics. You will spend more trying to fix it by some backyard mechanics than to buy a new one. Please do us all a favor and use equipment that is working properly. Parting with 60 bucks is cheap compared to a new model or worse, a hospital bill.
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Old 06-04-2007, 08:21 PM
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DickCorby
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My DX-6 on occasion takes a bit longer to connect as well. I think that is nothing more than it has to search longer to find a a pair of SS frequencies that it is happy with. Once the lock on occurs, its busines as usual.

Having been in Electronics for many years, I make it a point after any piece of electronic equipment gets hot, to suspect every component in the entire system. And make sure before flying again that I have gone over every component with a fine tooth comb. If it means replacing a $60 receiver, so be it. Better than having another failure that can cause much more than the $60, or even worse, hurting someone.

There was an incident this weekend involving the big gassers here in the northwest. A Flyer had a transmitter battery pack get hot while charging and changed it to a new one. Ran a range check, and all seemed fine. Fired up the gasser, ready to launch and everything went banannas, throttle went high, control lost and the plane headed for two pilots on the flightline. Not in the Safety cages as they should have been. They had to run to keep from getting hit, and in the process crashed a brand new and expensive IMAC plane. The owner of the out of control plane nearly got chewed up trying to stop it, and finally got the ignition turned off.

Hind sight says there could be a number of things contributing to this.
a. the pilot that had the hot battery perhaps should not have flown until he really was sure the equipment was safe to fly. Though he did get a good range check after the battery replacement. And the system works normally now after the incident.
b. Had the pilot of the crashed plane been in the safety cages, he would not have had to run for safety, and kept the plane in the air under control and not plowed it into the ground.
c. Unfortunately, it was not his plane he was flying, but helping the owner tweak his plane for competition. The owner is now out a plane.
d. And nobody knows for sure, but perhaps someone in the pits turned on the same Freq. that caused the out of control situation. It was a crowded day, and no real Frequency Control was in effect. Of course nobody came forward and said they did turn on for a second to check something.

So taking a chance on the electronics is really dangerous. Eventually it will come back to haunt you, sometimes sooner than you think.
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Old 06-04-2007, 10:49 PM
  #11  
LOW-N-SLOW
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Twice now I've been asked to help newbs with newb planes that were going spastic during basic 30 paces, antenna collapsed radio check. Both times I was lucky and looked like a genius hero when we just went in and twisted all the 3 wire leads so they were individually corkscrewed, like a telephone handset cord - instant fix! Apparently this breaks up some sort of field effect created by parallel wires...?

I also have a homebrewed Stryker with a FMA M5 Rx that occasionally jumps to 1/2 throttle and freezes (won't shut down) on throttle up while the elevons jerk and glitch uncontrollably. If I re-tuck the battery leads a little deeper as far as possible from the Rx (can't really do much in the narrow channel, they have to be strung alongside the Rx between the rear mounted ESC and the forward battery cavity) and re-boot the system all is well again.

This the only time I've had a problem with one of my many M5's convincing me that wire routing is a critical factor in a glitch resistant set-up. So my 1st suggestion is to change the way your spaghetti is laying in the fuselage.
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Old 06-05-2007, 10:30 AM
  #12  
West-Oz
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An intermittent glitching problem that kept me grounded for ages turned out to be bad connection inside a nicad RX pack. Everything tested OK over and over but servos buzzed and deflected without warning. Swapped out components, RX, servos etc, but did not suspect the battery pack because the LED indicator, although behaving bizarely at times, eg all LEDS lighting up together, always seemed to indicate full charge.
After about six months I decided to charge it up to have one last go at fixing it and it would not take a charge as the bad connection had finally fully failed. A new pack and problem solved.
Tim.
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