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Old 2007.03.08, 11:35 PM   #1
kchan
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Help! No Throttle Response, Motor Run Away with Switch Off!

I drove my MA010 tonight. It suddenly stopped responding to throttle input. When I switched it off, the motor went full throttle.

I took the AD board out and found no burnt on the FETs. I don't know why the switch off position can cause some kind of short circuit that drive the motor. If I connect power to the board, it drives the motor when the switch is set to off position. The steering still works though.

I have seen a post regarding a similar issue, but there is no follow-up on it. I did a few searches, but I could not find anyone else who has the same issue. Has someone experienced the same problem and found a fix for it?

Btw, I have a PN Speed AWD stock motor in it and use 2S Lipo battery.

Thanks a lot for your help.
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Old 2007.03.08, 11:58 PM   #2
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Do you have upgraded FETs? if so, check for a faulty soldering job. If not, it could be the li-pos. But if steering still works, maybe it's the motor.
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Old 2007.03.09, 12:05 AM   #3
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Thanks for your reply. I have not upgraded the FET yet. I tried to look for burnt mark or shorting, but I have not found any. The motor should be ok though because it still runs when the car is switched "off". It is just very strange. I thought switching it off would cut power, but it shorts the circuit instead.

I have seen repair service offered by ********** and ******, but I am not sure if they can fix it if the FETs are fine.
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Old 2007.03.09, 12:57 AM   #4
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the names will not show. anyways, are your li-pos soldered directly to the board, or through a deans plug?
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Old 2007.03.09, 12:53 PM   #5
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It is my understanding that the switch is more of a ON or standby...not really off. I have been told that there is suppose to be a small amount of power draw even when the switch is flipped to the off side. One way to find out is checking the leads to the switch and check for continuity. If this is the case, your board may be toasted. If not, then your car must be possesed!
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Old 2007.03.09, 02:46 PM   #6
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The fets are fried. They don't necessarily have to be visibly damaged to be burnt up. Ad band and lithium don't go very well together.
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Old 2007.03.09, 04:31 PM   #7
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if u turn off switch and the car starts full throttle... its fried.
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Old 2007.03.09, 05:57 PM   #8
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Well, all I can say is I'm sorry for your loss.
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Old 2007.03.09, 11:45 PM   #9
kchan
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Thanks for advice everybody. At least I know it now it was fried.

If it is fried, what can I do to repair it. I wonder if I can replace the FETs or install an external turbo to bypass the problem.

It is quite expensive to replace the whole AD Board. It costs around $100 for the whole set. An external turbo costs around 50-60 which can solve the lipo-AD Board problem altogether.

Thanks again for your advice.
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Old 2007.03.10, 09:06 AM   #10
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Just replace the fets... $1-$3 each... only need 2... you will want to replace them both just incase...
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Old 2007.03.10, 11:47 AM   #11
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yeah, you can get really cheap FETs at some places.
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Old 2007.03.10, 11:53 AM   #12
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I am relieved. At least I don't have to replace the board.
Soldering such a small component is challenging to me, but I can send it out for repair at the worst case, which is still way cheaper than getting a replacement board.

Thanks a lot for your advice.
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