Q-40 Racing Discuss AMA 422 and any other variants of Quarter 40 racing

Q40 servos

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Old 04-13-2011, 12:56 PM
  #1  
izzy
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Default Q40 servos

Hi guys
I have a Loki q40 and had on 2 occasions aileron servo decide to stop working for a few seconds
At first I thought it was a PCM lock so I changed to 2.4Ghz
But then locked again so I am sure servo is acting up
Found the extension female connector pins loose but am not sure that that is the problem
If anyone has a way to check this I would be glad to know how
In the meantime looking to replace JR 3241 servo in the wing
Would the JR MN48 sport servo work for this
Any one using it on their Q40
Would like to know
Since I only use this plane for fun (with ss nelson Q40)
I doubt I need to get another 3241
Thanks izzy
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Old 04-13-2011, 01:19 PM
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bigtrev@xtra.co.nz
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Default RE: Q40 servos

interesting- I was out flying yesterday with my mate - he was practicing for the forthcoming F3d w/c in Australia......before going flying he had the ailerons fail- everything else worked except them. it so transpired to be a faulty Y lead- he runs two wing servos. It had us thinking- what was different to previous sessions? We pulled the Y lead apart and for some unknown reason there was a 'chip' in the lead....never seen one there before. I had given him out of my F3d model a LiFe battery which he had installed just prior to departing to the field. Yes, had the 'chip' burnt out on the 6.6 volts?.....we haven't yet assessed that , but one wonders whether the chip has a maximum of 6 volts.....perhaps even only 4.8?
The lead he tells me came with a HITEC 2.4 GHz radio.He had been in the past using Lipos and a 6 volt regulator without any apparent problems Can anyone solve this problem for us? THnz
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Old 04-13-2011, 01:41 PM
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Default RE: Q40 servos

are there any markings left on the chip in the lead? It may be possible that the higher voltage LiFe pack burned it up. 6.6 is the nominal voltage - they start out above that, 7.2 or so.

Some may be amplified - trying to run two servos off one channel on a receiver, especially newer receivers that have lower voltage pulse outputs to begin with, may drag pulse amplitudes down far enough to cause servos not to respond.

If possible, I would use an extra channel on the receiver and mix the aileron function in the transmitter - some even have dual aileron servo functions built in.

I would be very hesitant to use a Y harness of any kind in a race plane - too many things to go wrong.

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Old 04-13-2011, 03:54 PM
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bigtrev@xtra.co.nz
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Default RE: Q40 servos

thanks-yes, it had gone through my mind that a better solution, irrespecttive of this problem may well have been to use the additional channel as you suggest. The Life as you correctly say is around the 7.2 volts at full charge- suspect though that the inbuilt tolerance of the chip would have taken that voltage.....looks like we are wrong. My F3d model had only one servo serving the two ailerons and the circumstance was therefore quite different. thankyou for your help, THnz
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Old 04-13-2011, 07:05 PM
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izzy
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Default RE: Q40 servos

Anyone have a reply on post number 1
thnx
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Old 04-13-2011, 08:13 PM
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Default RE: Q40 servos

I have used MN48s in Thunder Tiger powered Q500 planes, and while it's the same size as the 3421, it's not quite in the same class. I'm not sure I'd use the MN48 sport servo in a Q40 plane.

Others may have more experience with them. I understand your thoughts, though - it's roughly a third the cost of the 3421 digital!

And if you're looking - I've used the Spektrum A5030 servo briefly - it's a low cost digital, about the same size. At 4.8V it was a nice servo, at 6V it was "nervous" when moving - didn't get smooth movement that tracked the stick, it wanted to jump around. I tried it with a regulated 6V, the local hobby store tried them with a fully charged 5 cell NIMH pack with the same results. I had my hopes up, but wasn't comfortable with the way they worked at 6V and above.

I am tempted to go back and buy a couple of them and experiment with regulator settings, see just how far above 4.8V I can go and still have smooth response.

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Old 04-14-2011, 03:32 AM
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daven
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Default RE: Q40 servos

No I would not use the MN 48's on a q40.

I like them for sport quickie, but nothing more. There are only 4 servos I recommend for Q40 (even with a Short Stroke)

JR 3121 or 3421
Futaba 9650 or 3002
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Old 04-14-2011, 01:08 PM
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izzy
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Default RE: Q40 servos

Daven hi
Thanks for the input
I have 2 9650 lying around so I will try that however the specs on tbd mn48 are quite similar to that of the 9650 as far as torque goes
That's why I thought they would work
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Old 04-14-2011, 07:16 PM
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Default RE: Q40 servos

the 9650 center better and have a more durable motor and gears.
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Old 04-15-2011, 12:08 AM
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Default RE: Q40 servos

In reply to that faulty lead, I suppose if you had a decent radio / wire leads / servos that matched the radio set you wouldn't get problems.
My suggustion is go buy a Futaba 12 FG 2.4 & your troubles will be over. LOL
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Old 04-15-2011, 10:08 AM
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Randy Smith
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Default RE: Q40 servos

I am presently trying out the Spektrum A5030 servo in my E-F1 model. I know this is not the same stresses as Q40 for sure, but just giving them a try for now. If they are successful, I will move to 426 Quickie and maybe Q40. I am running regulated 6.0 volts. Haven't had any "nervous" issues with the servo but I do notice the gear train and motor is more noisey than the 3421. I am using nylon gears in the A5030, 3421 is metal gears. So far the A5030 is working fine and for $20.00 it's a steal of a deal.

The other option is the Spektrum H5000 digital helicopter servo. This is an excellent servo and equivalent or better than the JR3421 in my mind. The H5000 is a $55.00 servo however.


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Old 04-15-2011, 10:41 AM
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Default RE: Q40 servos

Randy - good to hear on the 5030's. We tried all of them my LHS had in stock, and they all were "nervous" on 6.0V and above. (6.6, etc). 4.8 they were fine.

Maybe there were a few that weren't as smooth as the rest, and my LHS just happened to get some from that batch. I am going to try them again, always figured I would, just haven't done that yet.

ALso, your experience with the H5000 is good? I've considered them, too - good specs, the right size to fit in a Q500 or Q40 (or EF-1) and they're still less expensive than the 3421's.

I did pick up a couple of Futaba 9650's when tower had them for 49.99 one day, looking forward to trying them, too.

Keep us posted on your experiences with those A5030's - a 20 dollar digital servo would be great!

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Old 04-15-2011, 05:21 PM
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izzy
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Default RE: Q40 servos

FOUND THE PROBLEM
the problem actually lies in the hinge line of the plane and not in the servo
the balsa below the fiberglass skin has detached itself from the fiberglass skin and also balsa cracked along the hinge line, thus causing the aileron to flex straight under load and create an effect as if i had no control
thats why as soon as i cut the motor , i regained aileron control

now to see how to repair the aileron
anyone have an idea?
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Old 04-15-2011, 06:33 PM
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Default RE: Q40 servos


What is the chip for? G
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Old 04-16-2011, 06:51 PM
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Bill Vargas
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Default RE: Q40 servos

ORIGINAL: izzy

FOUND THE PROBLEM
the problem actually lies in the hinge line of the plane and not in the servo
the balsa below the fiberglass skin has detached itself from the fiberglass skin and also balsa cracked along the hinge line, thus causing the aileron to flex straight under load and create an effect as if i had no control
thats why as soon as i cut the motor , i regained aileron control

now to see how to repair the aileron
anyone have an idea?
Izzy, If you can find one of these,,, fill it with some thin or medium CA and inject the cracked balsa and or where the balsa has delaminated from the fiberglass.

With the wing laying upside down on your bench,,, Stick the needle thru the bottom side of the wing and then get the "feel" for when the needle touches the balsa on the bottom side of the topside of the wing,,, in other words don t punch thru the top of the wing,,, then hit it with the CA,,, Several applications along the cracked and delaminated balsa,,, will do the job!

Once you feel that you have applied enough CA,,, Here's the Hard Part,,, "walk away and leave it alone for a while" till the CA sets up.

If you happen to stick your finger,,, the bleeding will stop in a matter of seconds due to the CA


BV
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Old 04-18-2011, 07:51 PM
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izzy
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Default RE: Q40 servos

Bill hi
thanks for the help
i have sorted the problem
all looks great now
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Old 04-19-2011, 02:51 AM
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Default RE: Q40 servos

They use the same chip at the S.P.C.A. LOL
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