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HeliHobby . Ron’s HeliProz South . Century Helicopter

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Radio - Servo - Gyro - Gov - Batt > 9254 servo issues
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

so, we were at one of our fields today flying, probably burned 3/4 of a gallon. well, my last flight, i was coming around from a turn and i lost my tail control for about 1 second and then it regained, almost ended up in knife-edge to the ground, but was able to recover nicely as soon as the servo regained control... my question is this... what would i be able to do in order to bench test it and see what the possible cause would have been??? i am also running 3x hitec hs-5985mg on my cyclic, so i know those are pulling a lot of draw on the rx pack, and my rx pack is a 6.0v 3200mAH pack...
05-04-2008 09:43 PM
 
 
Dr Lodge
Elite Veteran
Location: Guildford, Surrey - UK

Sounds like the servo motor is on its way out. On the bench, apply some pressure to the horn while you move the servo via the Tx and see if it operates properly.

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Sorry for the long note, I didn't have time to write a short one.
05-04-2008 09:56 PM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

this thing is only about 4 months old too, i would hope the servo motor is not on its way out...
05-04-2008 09:58 PM
 
 
Dr Lodge
Elite Veteran
Location: Guildford, Surrey - UK

It might be, alot of people have reported issues with the 9254. I have had 2 or 3 burn out on me. One burnt out very quickly as it was jittering due to the gyro amp being near another servo.

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Sorry for the long note, I didn't have time to write a short one.
05-04-2008 10:04 PM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

well, i bench tested it...

seems to be strong and gives good resistance...
05-04-2008 10:07 PM
 
 
baddraptor
Elite Veteran
Location: valencia, ca- usa

How many flights? What heli? 3/4 of a gallons is probably 7 flights, thats alot of flights. When the battery is low the first thing to go is the tail.

**Unattended children will be givin a shot of espresso and a puppy**
05-04-2008 10:09 PM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

its a century raven 50...

i have a field charger and peak after 4 flights...

i did have an issue earlier on with the engine cutting out, like it was going to throttle hold, so i turned off the battery fail safe on the gov thinking that the servos on the cyclics were pulling a large amount of draw from the rx battery and tricking the gov to think the battery was low, when it really wasnt because it only happend when i was pulling a hard turn, loop, tumble, etc, etc...

i may end up going to a 4800mAH rx pack in the near future, but it was the last flight of the day that the tail did this... just checked the rx pack and it shows 6.4v
05-04-2008 10:19 PM
 
 
dkshema
rrProfessor
Location: Cedar Rapids, IA

Quote 
i may end up going to a 4800mAH rx pack in the near future, but it was the last flight of the day that the tail did this... just checked the rx pack and it shows 6.4v


SERVO ISSUE == NOT.

OPERATOR ISSUE == ABSOLUTELY

The S9254 IS NOT RATED FOR running on 6.0 volts or greater.

Running your 9254 on greater than 5.8 volts is a sure fired way to fry the darn thing. The 9254 WILL DIE a slow, agonizing death when run from anything greater than 5.8 volts.

Since you're beginning to see it act up, it's time to stop cooking it any further. I would suspect that you have already damaged the electronics in the servo. It's time to replace the 9254 before it goes completely dead on you, and BEFORE you fly again, do something to limit the voltage to the 9254 to no more than 5.8 volts with your fully charged pack.

-----

* Making the World a Better Place -- One Helicopter at a time! *

Dave
05-05-2008 05:04 AM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

sorry, forgot to add that i am running a step down regulator to 4.8v on it, lol... my bad
05-05-2008 05:32 AM
 
 
helimatt
Key Veteran
Location: Lafayette, IN

The Stepdown will only drop like .7V, so on a 5-cell NiCd or NiMh pack you are still over-volting the tail servo. I found out the hard way on a Logictech tails servo- the motor fried running the same setup you've got there.

Regulated 6V with a step-down is fine. Unregulated 5-cell is up to 7+V fully charged, so still over 6V stepped down. Just too much for the little guy.

Never, ever, ever, ever give up.
05-05-2008 02:07 PM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

yeah, i just checked the voltage on it before and after the step down, its at 6.34 before and 6.13 after, could be a faulty unit i guess, but im looking into a regulator right now too to regulate the whole system to 6.0v
05-05-2008 07:57 PM
 
 
helimatt
Key Veteran
Location: Lafayette, IN

Okay there's the problem. You probably need to replace that servo now.

The step-down is just a diode, drops approx. .7V, not regulating to any particular voltage. Sometimes its referred to as a 5.1V step down (Align makes this statement), because their regulator output os 5.8V, so the step down of .7V gives the 5.1V.

Never, ever, ever, ever give up.
05-06-2008 04:18 AM
 
 
tchavei
rrProfessor
Location: Portugal

emcotec makes a mini (3gr) regulator for the tail. It just plugs in like a normal step down but it isn't a diode so you have steady 5.2V regardless of input (5.2-8.4V). Max rating is 2amp continous.

That was the solution I used when I bumped up my reg to deliver 6.57V constant.

Tony


--------------------
"Perfection and patience usually walk side by side..."
05-06-2008 12:02 PM
HOMEPAGE  
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

still working on this...
05-07-2008 01:29 AM
 
 
az_heliguy
Senior Heliman
Location: Florence, AZ

alright...

finally was able to resolve the issue... removed the alight step-down (junk) and replaced with a constant 5v regulator and everything is all good now...
05-08-2008 05:26 AM
 
 
Lewd Skywalker
Senior Heliman
Location: Manila, Philippines

hi!

same issue here on sceadu evo50, got same 9254 + 401 running 5.1v regulator, one time heli twitched and totally lost control (full pirouette). good thing heli was safe (auto'd).

on ground initially servo isn't moving, moved the arm and the servo functioned again. now i'm afraid to use it, just found a bnew 9253 and will test on the heli this weekend.

can't find anyone brave enough to test my 9254 which is just 3 mos old when it suddenly became erratic once.

may i ask, is the (older) S9253 better in terms of reliability than the S9254???

thanks

Freya EX-II
Freya Twister
Lepton EX
PHI-015
05-08-2008 08:01 AM
HOMEPAGE  
 
 
frickey295
Heliman
Location: Avenel NJ USA

Wanted to throw my .02 in here
My tail started twitching a few weeks ago and at one time swung around about 45 degrees . I have had the 9254 with the 401 in my raptor then evo 50 then 600 n and has worked great. After pulling apart the 9254 there was a large amount of oil residue in the servo case. I mean DROPS of it kinda drowning the circuit board. I used some zero residue contact cleaner and put it back together and its now fine and has been since. Your voltage issue is most certainly the primary cause as dk stated but it is also important to look at servo maintainence as well. I am sure you will solve your problem since there are a great bunch of people on this site

Good luck

Fran
Trex 600 pro Futaba 611 Os Hyper 9451's
Trex 600 sport TT Redline BLS 451's
05-08-2008 12:30 PM
 
 
Lewd Skywalker
Senior Heliman
Location: Manila, Philippines

frickey: sir same with me here, I just took the 9254 apart and the bottom case/cover is covered with oil. the PCB with the SMT components are soaked with oil. I used contact cleaner also to dry everything with oil and put it back together. it works fine now but I can't bear to test fly it in my heli

probably these servos aren't sealed well even with the small rubber lining around the servo case. the servo is boom-mounted in my Sceadu and I do have a deflector but it still get's oil-wet specially when doing flips and backwards flying.

Freya EX-II
Freya Twister
Lepton EX
PHI-015
05-09-2008 04:23 AM
HOMEPAGE  
 
 
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Radio - Servo - Gyro - Gov - Batt > 9254 servo issues
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