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DX6i + 480Li ESC = erratic

Old 01-19-2009, 07:29 AM
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Default DX6i + 480Li ESC = erratic

I'm getting a new plane ready but having a little trouble with throttle control.

I have a Permax 400 motor (brushed) controlled by a GWS ICS-480Li ESC, powered by a 3S 1700 mAh LiPo pack. Radio is a new DX6i with the 6200 diversity receiver pair... Antennas are oriented 90 deg to each other, one athwartships and one fore-aft. The ESC is flush with the outer surface of the airplane with the transistor tab exposed to the airstream.

The airplane electrical system powers up and the control surface servos work fine, but the motor speed control is erratic. I get occasional bursts of throttle with no throttle commanded (scary), and varying motor speed when I command a steady 25% or 50% throttle.

I thought I had an ESC problem, but standing fifteen feet away with the DX6i transmitter and moving the transmitter around (while not touching the sticks) causes the motor speed to vary.

Doing the range check function on the transmitter causes the motor to pulse on and off every few seconds at a steady rate.

Anyone have a clue which component might be causing trouble, or where (and how) to start troubleshooting? I am new in the hobby so swapping in "known good" spares (i.e. ESC, reciever) is not going to be possible.

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Old 01-19-2009, 11:52 AM
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With no parts to swap out, first guess would be to make sure the battery is charged, but that doesn't explain the motor starting with throttle down. So secondly, check on your throttle trim rates to see if they are set to zero or less. You might have a couple of problems going on.

Has this set up ever worked correctly? Is there a hobby shop nearby to bring your stuff to?

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Old 01-19-2009, 03:06 PM
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I'm having problems with my 480Li also... I'm also using a DX6i with a AR6000 receiver. 3S, 1000 Mah lipo. Throttle control is fine, but the problem appears to be the BEC dropping out. Control will be fine for a couple minutes, then the throttle will drop out and no servo actuation. After a minute of not inputing control changes, it'll rearm and work for another minute or so. It'll do this even with the motor disconnected!

Previously, I had a ICS480 brushed ESC with no problems at all...

I've got a couple Eagle 30A ESC's on the way ($7.44 ea. from Hobby City), so I'll see what they do...
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Old 01-19-2009, 03:22 PM
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Dk_aero, your problem is almost certainly from your servos drawing to much power and the BEC dropping out, it's classic "brownout". make sure your running 4 or less small (< 9 gram) servos and that they are free moving. If there is binding in the servos they will pull more power.

Eddy, can you take the plane outside and see if it still acts erradicly when your ~15 feet away? there's a small chance your getting radio feedback (which shouldn't be a problem on 2.4. but it's easy to diagnose) Otherwise you might have a bad component somewhere.
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Old 01-20-2009, 06:04 AM
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Thanks for the suggestions. The problem is pretty intermittent making troubleshooting difficult.

At one point I did do one of the few component substitutions available to me... I went back to controlling the Phoenix sim with the DX6i, and was surprised to notice motor speed varying as the transmitter was moved around (and this was operating over the USB cable). The problem seemed to go away (in Phoenix) after I cycled the throttle trim switch several times.

It stayed away while testing the ESC/motor combo at varying voltages with a 12V 10A bench power supply (verifying that infamous GWS 8.2V low battery cutoff). But then it re-appeared while doing some further static testing using the 3S battery. Go figure! Still don't know if I have a radio problem or an ESC problem or an interaction between them.

The flakiness doesn't seem as bad outside, and doesn't seem to affect mid and high power settings, so I gave in to temptation and did a flight this afternoon... without any problems or even symptoms of problems.

At this point I'll just have to keep an eye on it and try to build up a larger troubleshooting database of when it happens, and when it doesn't.

Thanks again for the suggestions,
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Old 01-20-2009, 06:14 AM
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If that was happening while on the SIM it sounds like a bad TX. I'd heard rumblings in the heli forums on another site about similar issues.

I'd seriously consider sending it back to Horizon to have it checked over.
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