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HomeRC & PowerAircraftHelicopterRadio - Futaba FASST › CGY-750, 8FG, Whiplash random tail twitch
10-28-2012 07:37 AM  6 years agoPost 1
diggyduo

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New Zealand

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Okay. So it's been a marraige in heaven running the CGY on my Whiplash E. It's fitted out with MKS HBL 665's and an HBL 980 on the tail. I'm running a WR Hercules at 8.4V, HKIII 4035-560, and a CC HV 120. The last couple of flights two days ago, we noticed a couple of really fast, random tail twitches, but couldn't replicate it on the ground (they usually only twitch 'once' then they're gone). In the art of having no idea what to look at for this, I pulled the wiring apart, put it back together, and made sure the tail servo wire was separate from the ESC throttle cable, and reset the cgy back to std 600-700 settings. Yesterday, the heli flew fantastic for the most part, but the really fast, random twitches still occured a couple of times in the first few minutes of flight.

So last night, I swapped the tail servo out for a brand new HBL 980, re routed the cabling some more to separate the tail servo wire further from the ESC/BEC/ESC cables/BEC cables.I put the old servo on another heli, and it performed fine - no twitches.

However, the same thing occured today on the whiplash. It seems to be exacerbated by hard rudder movements, but it's still pretty random and a different movement to the tail twitches you get from having the gains up too high (I've reduced the gains to 30 and still no change).

I used the transmitter on my other heli's with CGY's and they all work fine, so I assume it's not the tx going west.

Has anyone seen this weird tail twitch with CGY 750's and got a solution, or do you think I need to look elsewhere on the heli?

Cheers

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10-29-2012 02:08 AM  6 years agoPost 2
Dr.Ben

rrMaster

Richmond, VA, USA

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Do you by chance have another 750 that could be used to see if the problem lies outside of the FBL controller?

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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10-29-2012 05:30 AM  6 years agoPost 3
diggyduo

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New Zealand

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Yeah, it's been musical CGY's of late between the fleet. The screen died on one of mine so i've been swapping the two remining amongst the three helis. I'll change htem about tonight.

I need to dig around and find the programme that lets you save the CGY settings - paranoid that I'm going to reverse a gyro in one of these swaps........

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10-29-2012 01:53 PM  6 years agoPost 4
marc8090

rrElite Veteran

Long Island, N.Y.

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When your screen died did you swap just the control box or the sensor also? The boxes and sensors are matched sets and can not be mixed.

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10-29-2012 06:14 PM  6 years agoPost 5
diggyduo

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New Zealand

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Hi Marc

I've been pulling the amp and sensor off together as a matched pair.

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10-29-2012 06:16 PM  6 years agoPost 6
stevehof

rrApprentice

Oceanside, CA, USA

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Just went through a similar nightmare with a Vbar set up on a Synergy E7 torque tube model. I swapped out every electronic component and wire in the ship with no help. The Vbar event log was full of checksum errors along with all sorts of other control surface errors. The main symptom was hard tail twitches 10 to 30 degrees or so. I also got occasional cyclic twitches.

Grounding the carbon fiber chassis at the motor mount bolt to the negative battery wire of the ESC FIXED everything. No more twitches or event log errors. My personal opinion after this episode is that all carbon fiber framed ships running FBL should have a true negative chassis ground.

Synergy E7, Vbar 5 Pro, BLS255 & 256HV Hacker Turnado 530KV LE, Rail 696, CC120HV, WR Sup BEC | 18mz

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10-29-2012 06:53 PM  6 years agoPost 7
diggyduo

rrNovice

New Zealand

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Did you put the grouding cable between the motor mount bolt and metal motor mount, or between the metal motor mount and carbon frame?

I'll this if the cgy unit switch doesn't fix anything. Not sure why it would would start having static issues when previously it seemed fine - perhaps the change in weather over the weekend - but its worth a shot.

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10-29-2012 07:42 PM  6 years agoPost 8
stevehof

rrApprentice

Oceanside, CA, USA

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Just twisted the wire under the bolt head. My E7 was fine all year and well over 200 flights. The problem came out of nowhere one day the tail kicks getting so bad after a few days that it occurred nearly every flight. VbarLogs on my other identical E7 were clean and it would fly fine on the same day the other was wigging out. Go figure...? Edit, BTW, I actually put the grounding wire between two 3mm washers, then tightened the motor mount bolt. That way the wire doesn't get any extra twists or stress.

Synergy E7, Vbar 5 Pro, BLS255 & 256HV Hacker Turnado 530KV LE, Rail 696, CC120HV, WR Sup BEC | 18mz

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10-30-2012 06:22 AM  6 years agoPost 9
diggyduo

rrNovice

New Zealand

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Wow, bet that was a frustrating period Steve. Weird how electrical problems like that can develop over time - kinda only expect that with mechanical stuff as it wears.

Well, today tested the whiplash again with the unit swapped off my 550, without the grounding cable initially and no more random kicks. Got 5 flights on it, then tried the 550 with the cgy previsouly on the whiplash. No random kicks on that either.

For completeness, I swapped them back over again and the random twitches reappeared on the whiplash first flight.

So I've swapped them back again (thank god for the link programme) and left it at that none the wiser really, apart from surmising maybe one of the cgy's is more susceptible to emi noise spikes.....at least they are flying again

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