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Strange Glitch with radio, receiver or servo?

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Q-500 Racing Discuss AMA 428, AMA 424, and any other variants of Quickie 500 racing

Strange Glitch with radio, receiver or servo?

Old 09-11-2010, 11:42 AM
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grubs4flyn
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Default Strange Glitch with radio, receiver or servo?

Guys, I have a glitch in my JR 8103 converted to Spectrum with module. I have Spectrum AR7000 receivers and HS225BB servos. I had a crash in the spring practicing 3 pole with Viper and TT. The crash was brushed off as pilot error or wind until the other day when performing a pre-flight check, I noticed the lower V-tail control servo dead in neutral. Lower meaning bottom part of the V in a 90 degree left roll prior to full up for a turn. I think not having lower v working and the upper v in full up would cause the aircraft to yaw to the left and cork screw into the ground. This may explain the strange crash this spring. I turned off the flight pack and receiver several times, but still dead on lower V. Took the wing off, check connections, still dead. Popped the rear hatch, no humming or power apparent on lower V servo... However, when I manually moved the control arm. The servo started working again and has not failed in numerous hours of testing since. A friend who is an experienced Electronic engineer took the servo to his shop and tested it for hours. Bad news is that he could not find anything wrong with the servo. Does anyone have any ideas how to get confidence back with this radio? The glitch has only happened twice that I know of. First one in the spring may have caused a crash, but no proof. The second one I caught on the ground the other day after numerous flights this summer and one successful race. Now I am not confident with the flight pack and also suspicious of the transmitter too. Just getting another receiver and replacing the servo may just be a waste of money if the glitch is in the transmitter. Any ideas on how to troubleshoot would be greatly appreciated. I plan to call JR for their advice as well, but thought one of you fellow racers may have some ideas too. Thanks in advance.

Also, please comment on the expected behavior of a 424 aircraft in a full left turn without the lower V servo working. I have a friend that totally disagrees with my thinking and says the plane would yaw to the right and climb up??? Which of us is right?
Old 09-11-2010, 12:28 PM
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sahartman21
 
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Default RE: Strange Glitch with radio, receiver or servo?

I would plug the servos into the receiver as you were using.

Turn the battery on and move the servos, wiggle wire, and tap on the control arms of the servos. Hopefully this will show a jitter or servo stoppage.

My gut feeling is that you have a servo problem. It would be very rare to have a transmitter issue, but ...

If you don't find anything then mark the servo and use it for a less critical function such as throttle.

Good luck!


Scott Hartman
Old 09-11-2010, 01:03 PM
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jaka
 
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Default RE: Strange Glitch with radio, receiver or servo?

Hi!
Sounds as a bad servo! Or a bad connector plug.
Try another Hs 225 servo and see what happens.
Old 09-11-2010, 01:25 PM
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Default RE: Strange Glitch with radio, receiver or servo?

I agree, sounds like a servo issue.

Only having the right half of your V tail working would act as both up elevator and left rudder when you pulled up for the turn. Good recipe for a crash..
Old 09-11-2010, 06:14 PM
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Kevin Matney
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Default RE: Strange Glitch with radio, receiver or servo?

If you need that servo, to help a cost issue then mark it throttle only. Or just let it hit the trash can. The price of a servo is not worth the cost of the rest of it.
Old 09-11-2010, 09:52 PM
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SmokinJoe
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Default RE: Strange Glitch with radio, receiver or servo?

I was getting glitches with my 8310 system after converting it to Spektrum. In addition to two crashes when the Rx went off the air, I was frequently having difficulty getting the Tx and Rx to pair when switching on. Despite several re-bindings, the pairing difficulty would not go away.

After my second radio failure, I sent the transmitter back to the importer in January this year. The service technician found that the module case was loose in the Transmitter. When the module moved occasionally, I was losing the signal from the Tx to the Rx. Model Flight removed the electronic parts from the module case and fitted them into a newer style case that was a tight fit in the Tx case.

I've not had any more problems since getting the the new module fitted.

Old 09-11-2010, 11:56 PM
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grubs4flyn
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Default RE: Strange Glitch with radio, receiver or servo?

Thanks guys for your input.
Old 09-13-2010, 07:29 AM
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DMyer
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Default RE: Strange Glitch with radio, receiver or servo?

My money is on the HS225 being bad... have seen plenty fail - tie a loop in the lead to mark it as flawed and use it for parts (case, gears). The fact only one servo was failing leads me to believe the receiver or transmitter are not the problem.
Old 09-13-2010, 01:06 PM
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ALbert.S
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Default RE: Strange Glitch with radio, receiver or servo?

It is a servo problem I had the same thing happen The motor is the culprit DC motors get a dead spot If you move the stick very slowley you might be able to get it to stop on the dead spot Then the only way to get it to move is to manually move the servo Replace the motor or dump the servo I wouldn't use it on anything It cost me a airplane It was on the elevator It stopped on the ground check But then started when I moved the surface couldn't make it fail so took the plane up short flight stuck in up CRASH !!!
Old 09-13-2010, 02:14 PM
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Default RE: Strange Glitch with radio, receiver or servo?

I read with interest the above comments as a mate of mine had exactly the same problem. and the same radio........intermittent performance.

He checked the replacement module, checked the pin length- get a dial caliper for this and you'll find the problem......everything is a bit too short, and wont give total contact! Whats the fix- he simply unsoldered the pins in the transmitter that 'mate' the plug into the module and moved them out about 1-2mm and then resoldered. There is a firm here in New Zealand called Jaycar that sell longer pins......also in Australia I believe.

Also check the holes in the plug as sometimes they have an obstruction in them at the wire end- drill out with a suitable sized drill- on memory .8mm.

Some of the cheap Chinese 2.4 Ghz (Flydream) have the same problem- but you can pull apart the module and reposition the plug, gaining about the extra mm or so- but the plug holes also need drilling.
hope this helps- it certainly solved my mates problem,. trevor henderson, new zealand

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