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bobsyouruncle · 02-01-2015, 03:40 PM

Hey

I have a buddy with a nano who just swapped out his frame due to a broken canopy pin. After he was all done and tried to fly the thing he switched it on and the servos did their usual buzzing but also had a severe intermittent twitch, and the elevator servo barely moved. Upon spooling up it would tilt back full elevator and not respond to any inputs. While in idle the servos would respond but be twitching violently every few seconds. So it seems his tx is bound. He tried replacing the elevator servo which did nothing.

If anyone has any ideas it would be helpful.

sps3172 · 02-14-2015, 07:46 PM

As of this evening, I'm having almost the same issue. I, too, swapped frames to fix a broken canopy mount. When I put it all back together I did get about 5 seconds of normal hovering. Then I began experienced the random servo twitches and 'phantom' aft cyclic (swash tilts rearward). I also observed that all 3 servos do NOT give the 'up elevator' command. Only the rear servo moves, pulling the back of the swash down.

I read that you tried swapping servos. I just tried swapping the main motor and disconnecting the tail motor.....both to no avail.

As it stands, I can power the machine up and as long as I never advance the throttle, the servos operate normally. As soon as power is applied, the twitches begin and then I get full up elevator and ultimately it goes dead. Disconnecting the battery allows a repeat of the above.

It seems all but obvious that a new main board is in order. But, I'm wondering what we did (during the frame swap) to trigger this. I realize that these boards are known for failure, but it seems unlikely BOTH of ours just happen to fail as we swapped boards.

Dark Helmet · 02-16-2015, 07:57 AM

I have the exact same issue with my Nano CPX as well. Great Hobbies in Ottawa replaced the servo which didn't help. It turned out that the PCB with the servo on it needs to be replaced. The position sensor on that board has failed and that's why the servo judders violently. In my case it was the rear servo board which has the part No. SPMSH2026L.

I hope this helps.

Krinaman · 02-16-2015, 01:11 PM

My first thought when I hear servos twitching is to give them a shot of deoxite.

bobsyouruncle · 02-17-2015, 11:46 PM

The guy ended up replacing his 3n1 board and the problem went away. I can only guess that he damaged it somehow in the frame swap.

02-01-2015, 03:40 PM	#1 (permalink)
bobsyouruncle Registered Users Join Date: Mar 2014	Wired servo behavior after frame swap Hey I have a buddy with a nano who just swapped out his frame due to a broken canopy pin. After he was all done and tried to fly the thing he switched it on and the servos did their usual buzzing but also had a severe intermittent twitch, and the elevator servo barely moved. Upon spooling up it would tilt back full elevator and not respond to any inputs. While in idle the servos would respond but be twitching violently every few seconds. So it seems his tx is bound. He tried replacing the elevator servo which did nothing. If anyone has any ideas it would be helpful. __________________ DX8, Mcpx BL, Tarot 450 Pro V2

02-17-2015, 11:46 PM	#5 (permalink)
bobsyouruncle Registered Users Thread Starter Join Date: Mar 2014	The guy ended up replacing his 3n1 board and the problem went away. I can only guess that he damaged it somehow in the frame swap. __________________ DX8, Mcpx BL, Tarot 450 Pro V2

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02-14-2015, 07:46 PM	#2 (permalink)
sps3172 Registered Users Join Date: Oct 2006	As of this evening, I'm having almost the same issue. I, too, swapped frames to fix a broken canopy mount. When I put it all back together I did get about 5 seconds of normal hovering. Then I began experienced the random servo twitches and 'phantom' aft cyclic (swash tilts rearward). I also observed that all 3 servos do NOT give the 'up elevator' command. Only the rear servo moves, pulling the back of the swash down. I read that you tried swapping servos. I just tried swapping the main motor and disconnecting the tail motor.....both to no avail. As it stands, I can power the machine up and as long as I never advance the throttle, the servos operate normally. As soon as power is applied, the twitches begin and then I get full up elevator and ultimately it goes dead. Disconnecting the battery allows a repeat of the above. It seems all but obvious that a new main board is in order. But, I'm wondering what we did (during the frame swap) to trigger this. I realize that these boards are known for failure, but it seems unlikely BOTH of ours just happen to fail as we swapped boards.

02-16-2015, 07:57 AM	#3 (permalink)
Dark Helmet Registered Users My HF Map location Join Date: Jan 2015	I have the exact same issue with my Nano CPX as well. Great Hobbies in Ottawa replaced the servo which didn't help. It turned out that the PCB with the servo on it needs to be replaced. The position sensor on that board has failed and that's why the servo judders violently. In my case it was the rear servo board which has the part No. SPMSH2026L. I hope this helps.

02-16-2015, 01:11 PM	#4 (permalink)
Krinaman Registered Users Join Date: Feb 2015	My first thought when I hear servos twitching is to give them a shot of deoxite.

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