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Old 04-03-2006, 09:18 AM   #1
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Default Can a servo cause a glitch?

I swapped my complete electronics, other than the servo to my electric buggy and now I am getting glitches in both the steering and esc. I had no problems whatsoever before the swap. The motor has good brushes and only a dozen races on it. There are built in capacitors on the motor. I see only the most minimal of sparks between the brushes and commutator. I tried changing batteries, crystals and receivers to no avail. The only differences I can come up with are that I am running it in a different car with a different (used) steering servo. When I drive the buggy say 100 feet away from myself, it will dart erratically off in some direction. Its fine when up close, although the throttle seems to glitch slightly. The radio is Am. The esc is an old novak duster II. All wires are routed cleanly away from the antenna and receiver. The old servo seems a little worn and loose.

Any ideas?
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Old 04-03-2006, 09:40 AM   #2
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Hold the two rear wheels from rotating then at the same time, lift the front wheels off the ground and apply a TINY bit of gas. Enough gas to feel the car strain under whatever's holding the rear wheels from turning. If your servo starts bugging out, then you know it's your servo.
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Old 04-03-2006, 09:40 AM   #3
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Yes, a servo can cause a glitch. When one glitches, it can cause the other servo (or speed control in this case) to glitch as well. The only way to figure out exactly what is causing the problem is to switch out everything ONE THING AT A TIME. If you start doing multiple components, you'll never figure out which component is actually broken.
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Old 04-03-2006, 12:18 PM   #4
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Just swapped in my metal gear servo from my pan car and its still doing it. I'm switching to an FM radio and see if it cures the problem. Now I'm beginning to wonder if its the transmitter. At 25 feet, if I retract the antenna, the car drives off on its own. Shouldn't it have more range than that?
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Old 04-03-2006, 12:26 PM   #5
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I have another idea, perhaps misguided. If I install a reciever battery pack, might that eliminate power source problems, if for instance the bec on the esc is not doing its job?

Update: plugged a receiver battery pack into the receiver and with the antenna down, no steering glitch. Noticed the esc lights up and operates as I squeeze the throttle and reverse, but the buggy didn't move because I did not have a 7.2 battery hooked up to the esc. I then plugged the esc into a 7.2 pack and the buggy takes off when you turn the steering or walk more than 10 feet away with the antenna down. Seems to confirm that the esc is the source of the noise or problem. Damn. Didn't want to have to replace it. Still hoping the fm radio cures the problem.

Last edited by Iceracer; 04-03-2006 at 01:25 PM.
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Old 04-03-2006, 01:40 PM   #6
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Wondering if the aluminum chassis of the buggy is somehow conducting more interference from the motor to the antenna than the carbon fibre chassis of the pan car? I guess I'll have to pull all electronics and motor off the buggy and test them sitting on a benchtop to eliminate the buggy chassis as a source of the problem. I'm really hoping its not the esc as I hate to have to spend more dollars on a new esc.
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Old 04-03-2006, 02:16 PM   #7
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why not get the Spektrum DX2 transmitter set? You never have to worry about glitching or frequency/crystal conflicts with other drivers. It's $170 which is not bad to be completely rid of glitches.

Check it out on
www.spektrumrc.com
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Old 04-03-2006, 04:00 PM   #8
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Iceracer... I had this same problem in a BK2 buggy of mine and found out it was the Transmitter. I was totally suprised because it was a high-end futaba 3PJ radio. The probelm was the wiring on the battery harness. The wiring had gotten a tear in it and was effecting my ability to charge the pack I had installed. Because of this the radio's range was significantly reduced. Make sure you are not near any cell-phone towers, power transformers, or other sources RF energy. If your car still acts up, make sure you have ALL fresh batteries, or that they are fully charged. if that still does not fix it, try one of your buddies radios on it, just trade him RX crystals for a minute. Then go from there.
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Old 04-03-2006, 04:16 PM   #9
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Never thought of trying a different location. I'll have to take it to a parking lot somewhere and try it out. Too wet around here still with snow on most of the lawns.
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Old 04-04-2006, 08:24 AM   #10
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I've got one last idea to try. On the pan car, the servo and esc leads to the receiver were tightly coiled. Perhaps that acted like a choke (inductor) and blocked out interference? I'll try repositioning the receiver closer to the esc and coiling the leads to see if that reduced interference. Something changed, and I'm driven to figure out what.

BTW, what sort of reliable range do you guys typically get with your transmitters? I'm wondering if car rc transmitters put out less wattage than model aircraft transmitters.
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Old 04-04-2006, 02:07 PM   #11
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Most FM radios will be give good signals well to the point of being too dangerous to drive the car, as in you can hardly see what you are doing.

AM radios tend to be a different story as they are more susceptible to RF noise, but you still should be able to go more than 25 feet. I would expect an AM radio to give at least 100 ft of glitch-free range easily. The size of a nice track.
Some say that coiling your wires actually causes more glitching, not less, but the models I have had that I coiled servo wires on never had any issues.
You might even try placing your receiver on its side so that the crystals are on top, This is effective in Touring Cars with graphite chassis that create all kinds of noise.
I guess that you might have some damaged crystals as well, they can cause a whole range of problems from mild glitching to complete radio failure.
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