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Positive and Neg Shift

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Positive and Neg Shift

Old 02-20-2007, 05:36 PM
  #1  
rcbob51
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Default Positive and Neg Shift

I probably have smoked my new elect. system. I have a Hitec 555 receiver That is for Futaba J and says it is Neg. Shift. When I plugged the Battery in it started smoking and got hot like a direct short. I have an E-flite 40 amp speed controller for the E-Flite Park 480 motor. The Speed controller has brown and orange wires like it is for a JR system. On the ESC I don't see where there is a difference between JR and Futaba it is not labled or mentioned in the instructions anywhere. I have hooked up the Red as positive and Black as negative from the ESC to the Battery. Any Ideas what I did Wrong??? Can this problem be corrected by switching the battery leads?

Thanks for the help
Bob
Old 02-20-2007, 05:41 PM
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2slow2matter
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Default RE: Positive and Neg Shift

Negative/positive shift has nothing to do with power from the battery. That is simply the way the rf gets modulated. Sounds like there was a short. Maybe the receiver was defective from the start?
Were you using a lipo battery? If so, does it have a voltage regulator built in to reduce voltage to 5 or 6 volts? Maybe too much juice going through the rx?
Old 02-20-2007, 05:44 PM
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Montague
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Default RE: Positive and Neg Shift

The "shift" of the FM modulation is between the TX and RX only, and has no effect when hooking up your BEC or ESC anything of that sort. So a speed control will work with any receiver, not jut one brand or another. The same is true for servos, you can mix and match brands all you want.

(with the exception of some rare off-brand stuff, I'm talking about the most common brands you'll run in to)

I don't see anything in your post that is obviously wrong in how you hooked things up. I assume you have the motor hooked up to the motor leads and the battery to the battery side and you're not backwards there? And the BEC lead to the RX, right?

As long as the battery is plugged in to the ESC, and the ESC's BEC plug is connected to the RX, then the ESC should be doing the power limiting to keep the RX from being damaged. If you have too many servos or too much battery for your ESC, then you might fry the ESC, but probably not the RX. And it doesn't sound like that is the problem.

I do agree it sounds like something else is shorted. Are the motor leads shorted or something like that?
Old 02-20-2007, 05:53 PM
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rcbob51
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Default RE: Positive and Neg Shift

Thanks for the quick Response, I am new to electric flight. I Know that one of the cells on my 11.1 volt Li Po battery is shot, my blinkey balancer only lights up 2 cells now. Must be a short in the connection to the battery.

Thanks Again
Bob
Old 02-20-2007, 10:00 PM
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2slow2matter
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Default RE: Positive and Neg Shift

Something definately shorted and drained one of your cells--ruining it (more than likely). At least it didn't catch on fire--which is a real possibility with lipo batteries. Maybe your speed controler was bad? Hook up another battery to the speed controller, and (assuming it still works) hook a multimeter to the BEC output and read the voltage. I would do this before I hooked another receiver up to it. If the voltage is too high (over 6 or 7 volts in most cases) then send it back and demand that they not only replace it, but your rx as well--and your lipo battery.

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