8611 problem
05-10-2009, 02:55 PM
#1
8611 problem
I just replaced the 8411's in the elevators of my Kingcat with 2 brand new 8611's. The 8411's were perfect, they didn't glitch around, bounce, nothing, but I put a bigger engine on, so wanted stronger servo's. Well, the new 8611's are giving me problems.
The setup is, JR 12X 2.4 radio w/AR9000 receiver. Duralite power box running 2 7.4V lipo's. 2 new 8611's running through the power box.
At neutral both servo's are dead solid, when they are at full deflection they are solid, but through the travel both up and down, particularly the right servo's is bouncing on me about 1/2". If I put some pressure on the surface while moving it, it doesn't bounce.
These are both 2 new fresh out of the pack servo's. Any idea's from anyone?
Jeremy
The setup is, JR 12X 2.4 radio w/AR9000 receiver. Duralite power box running 2 7.4V lipo's. 2 new 8611's running through the power box.
At neutral both servo's are dead solid, when they are at full deflection they are solid, but through the travel both up and down, particularly the right servo's is bouncing on me about 1/2". If I put some pressure on the surface while moving it, it doesn't bounce.
These are both 2 new fresh out of the pack servo's. Any idea's from anyone?
Jeremy
05-10-2009, 03:26 PM
#2
RE: 8611 problem
Well, I think it might just be the power of a fresh battery charge, after about 10 minutes of playing with it, the bouncing seems to have gone away, just has me a bit concerned considering it didn't happen with the 8411's but is with the 8611's
05-10-2009, 04:57 PM
#7
Senior Member
Join Date: Nov 2005
Location: Henderson, NV
Posts: 2,778
Likes: 0
Received 0 Likes
on
0 Posts
RE: 8611 problem
If the voltage is being regulated through the power box, then it shouldn't matter whether or not the batteries were freshly charged. The regulated voltage should be the regulated voltage.
05-10-2009, 05:52 PM
#9
My Feedback: (6)
RE: 8611 problem
Regualted to what Jeremy. I don't know if Duralite actually tells you what the Powerbox regulates them to. Remember I had a problem with my Kingcat with the Powerbox and 7.4 Lithium Ion Duralites off a fresh charge. I changed my servos in the flaps and rudders to 8411's from 2721's and didn't have any more troubles with bouncing control surfaces. I find it odd with 8611's you are having troubles. I do believe I have 8611A's in my elevators and haven't had any problems there.
Good luck with the new engines hope to see you at Princeton.
Alan
Good luck with the new engines hope to see you at Princeton.
Alan
05-10-2009, 06:15 PM
#10
My Feedback: (75)
Join Date: Jan 2002
Location: Oceanside,
CA
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
RE: 8611 problem
I have the same thing on my 8611 on the flap if my F-4. It bounces until a "load" is put on it and then it's fine. It hasn't been an issue, but would love to know why!
Wex
Wex
05-10-2009, 06:47 PM
#11
My Feedback: (8)
RE: 8611 problem
Hey Jeremy,
A couple of thoughts on this for you.
First off are you using 8611's or 8611A's? Between the two servos they have different motors, amps, and top cases. If they are the older 8611's you will be fine, I just would not recommend them for use in a large IMAC/3D airplane.
We need to know what the voltage is coming out of the power box once it goes through the regulator. As stated above, Duralite likes to keep its customers in the dark regarding these points. You need to know. All JR servos can run a freshly charged 6 volt battery, which comes off the charger around 7.5 volts and drops into the 6.4 - 6.8 range almost immediately. The lithium batteries come off the charger at 8.4 volts and will drop down to about 7.8 - 8.0 volts immediately and that is too much. The amps being as precise as they are will sense flight control surface weight and with the high voltage will bounce like you are seeing. My first guess is you were seeing high voltage in the servos and once you got it down a bit they were fine.
Wex,
My first guess for you is your flap linkage is not working at the best nechanical advantage, and with this at one point the flap can probably move a couple of degrees and causes the issue of bouncing as the amp is trying to hold center, but with the chnaging pressure and feedback it will cause the bounce you see. Once there is a flight load on it I am confident it doesn't show itself. Easy to check, all you have to do is put a slight amount of pressure on the flap and see if the bouncing stops.
A couple of thoughts on this for you.
First off are you using 8611's or 8611A's? Between the two servos they have different motors, amps, and top cases. If they are the older 8611's you will be fine, I just would not recommend them for use in a large IMAC/3D airplane.
We need to know what the voltage is coming out of the power box once it goes through the regulator. As stated above, Duralite likes to keep its customers in the dark regarding these points. You need to know. All JR servos can run a freshly charged 6 volt battery, which comes off the charger around 7.5 volts and drops into the 6.4 - 6.8 range almost immediately. The lithium batteries come off the charger at 8.4 volts and will drop down to about 7.8 - 8.0 volts immediately and that is too much. The amps being as precise as they are will sense flight control surface weight and with the high voltage will bounce like you are seeing. My first guess is you were seeing high voltage in the servos and once you got it down a bit they were fine.
Wex,
My first guess for you is your flap linkage is not working at the best nechanical advantage, and with this at one point the flap can probably move a couple of degrees and causes the issue of bouncing as the amp is trying to hold center, but with the chnaging pressure and feedback it will cause the bounce you see. Once there is a flight load on it I am confident it doesn't show itself. Easy to check, all you have to do is put a slight amount of pressure on the flap and see if the bouncing stops.
05-10-2009, 07:23 PM
#13
RE: 8611 problem
Static power through the Powerbox is 5.75 volts. Under a load, the voltage is 5.5 volts. When I read the comments on a "fresh charged Li Ion", I thought you guys were joking. Since the Powerbox regulates the juice to the servos, your "fresh charged batteries" will never be a factor.
You are thinking back to the Nimh days when we did not use regulators. The servo jitter as it is called is a phenomena that has been around since the 8411 came out. It's the servo hunting for neutral...and pretty normal on IMAC birds. I see 8611As on many large jets doing the jitter dance quite often. It's no big deal.
If it starts jittering, just feed in a pinch of up elevator and watch it stop instantly (on the ground). In the air, it will be just fine.
Beave
You are thinking back to the Nimh days when we did not use regulators. The servo jitter as it is called is a phenomena that has been around since the 8411 came out. It's the servo hunting for neutral...and pretty normal on IMAC birds. I see 8611As on many large jets doing the jitter dance quite often. It's no big deal.
If it starts jittering, just feed in a pinch of up elevator and watch it stop instantly (on the ground). In the air, it will be just fine.
Beave
05-10-2009, 08:23 PM
#14
RE: 8611 problem
There seems to be a big assumption that the Power Box internal regulator is working properly. As John said, you need to determine the actual output voltage on that particular set up...................IMHO.
Having those 8611as jittering and bouncing can't be good..............
Tailwinds,
John
Having those 8611as jittering and bouncing can't be good..............
Tailwinds,
John
05-10-2009, 08:47 PM
#15
My Feedback: (75)
Join Date: Jan 2002
Location: Oceanside,
CA
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
RE: 8611 problem
John, it does stop as soon as there is any pressure on it and that is why it has never been an issue. It only is happening on one of the flaps, so I thought it might be the servo. Again, ANY pressure (flying or just touching it) and it goes away. I'm not really worried about it....just wanted to know the cause.
Thanks for your info and help.
Wex
Thanks for your info and help.
Wex
05-11-2009, 06:43 AM
#18
My Feedback: (3)
RE: 8611 problem
I have recently finished assembling my F-16 turbine jet, and installed brand new, out of the box JR 8611a servos. Both servos are mounted with no binding and move freely throughout servo travel. Servos have been tested in workshop during installation/setting and showed no sign of failure or unusual buzzing sounds….
On maiden day, luckily, I was doing usual range check and suddenly right elevator started wobbling up and down a few millimeters even when stick is moved, as if servo was not able to hold center position, furthermore, servo started buzzing abnormally.
I consider myself extremely lucky not to have had this defect during flight as this would surely have meant disaster with possibly no mean of knowing real cause…
Furthermore, back to workshop when I tried to operate servo, at the beginning, it worked without problems, after a few minutes (leaving power on) servo started to glitch again giving same weird noise.
Just to make sure that I had no problem with my wiring or RX, I plugged the servo directly to a new RX and had same failure.
Changed servo to a new one and problem was solved.
I am about to send defective 8611a for repair.
Regards,
On maiden day, luckily, I was doing usual range check and suddenly right elevator started wobbling up and down a few millimeters even when stick is moved, as if servo was not able to hold center position, furthermore, servo started buzzing abnormally.
I consider myself extremely lucky not to have had this defect during flight as this would surely have meant disaster with possibly no mean of knowing real cause…
Furthermore, back to workshop when I tried to operate servo, at the beginning, it worked without problems, after a few minutes (leaving power on) servo started to glitch again giving same weird noise.
Just to make sure that I had no problem with my wiring or RX, I plugged the servo directly to a new RX and had same failure.
Changed servo to a new one and problem was solved.
I am about to send defective 8611a for repair.
Regards,
05-11-2009, 11:23 AM
#20
RE: 8611 problem
The experience I have had tells me it's the extension leads, I have had this on more than one occasion and it's not the power side causing the problem it's the signal.
If you can, connect the offending servo/ control surface directly to the Rx or servo supply and see if it corrects the condition.
m
If you can, connect the offending servo/ control surface directly to the Rx or servo supply and see if it corrects the condition.
m
05-11-2009, 11:53 AM
#21
RE: 8611 problem
The Servo's are 8611a's and the Powerbox is the 40/24. I am going to charge the batteries again and check the output voltage on the powerbox, once the batteries have been on for a bit, the bouncing goes away, my guess is it's a problem with the regulator in the powerbox.
Just a guess though.... not sure why I didn't see it with any other servo's though.
Just a guess though.... not sure why I didn't see it with any other servo's though.
05-11-2009, 12:59 PM
#22
RE: 8611 problem
Jeremy,
I've got a load tester where that I could plug into one of the ports on your powerbox that will give a voltage reading under loads up to 3 amps.
I'll bring it by later this week when I'm back in town and we can run a test. This should tell us what the actual regulated voltage is coming out of the powerbox under loaded conditions.
I read somewhere some time ago that increased supply voltage to servos reduces the neutral deadband of the servo making it more sensitive around neutral. Problem is I can't remember or be sure of the source and it may only apply to analogue and not digital servos.
Is the voltage setting of the 40/24 adjustable?
PaulD
I've got a load tester where that I could plug into one of the ports on your powerbox that will give a voltage reading under loads up to 3 amps.
I'll bring it by later this week when I'm back in town and we can run a test. This should tell us what the actual regulated voltage is coming out of the powerbox under loaded conditions.
I read somewhere some time ago that increased supply voltage to servos reduces the neutral deadband of the servo making it more sensitive around neutral. Problem is I can't remember or be sure of the source and it may only apply to analogue and not digital servos.
Is the voltage setting of the 40/24 adjustable?
PaulD
05-11-2009, 01:13 PM
#23
RE: 8611 problem
Hmmmm...I just thought of something.
Are you using a Li-Ion PowerBox or a Ni-Cad PowerBox? The difference being the Ni-Cad version does not have a regulator.
Beave
Are you using a Li-Ion PowerBox or a Ni-Cad PowerBox? The difference being the Ni-Cad version does not have a regulator.
Beave
ORIGINAL: LGM Graphix
The Servo's are 8611a's and the Powerbox is the 40/24. I am going to charge the batteries again and check the output voltage on the powerbox, once the batteries have been on for a bit, the bouncing goes away, my guess is it's a problem with the regulator in the powerbox.
Just a guess though.... not sure why I didn't see it with any other servo's though.
The Servo's are 8611a's and the Powerbox is the 40/24. I am going to charge the batteries again and check the output voltage on the powerbox, once the batteries have been on for a bit, the bouncing goes away, my guess is it's a problem with the regulator in the powerbox.
Just a guess though.... not sure why I didn't see it with any other servo's though.
05-11-2009, 01:24 PM
#25
RE: 8611 problem
ORIGINAL: PaulD
Jeremy,
I've got a load tester where that I could plug into one of the ports on your powerbox that will give a voltage reading under loads up to 3 amps.
I'll bring it by later this week when I'm back in town and we can run a test. This should tell us what the actual regulated voltage is coming out of the powerbox under loaded conditions.
I read somewhere some time ago that increased supply voltage to servos reduces the neutral deadband of the servo making it more sensitive around neutral. Problem is I can't remember or be sure of the source and it may only apply to analogue and not digital servos.
Is the voltage setting of the 40/24 adjustable?
PaulD
Jeremy,
I've got a load tester where that I could plug into one of the ports on your powerbox that will give a voltage reading under loads up to 3 amps.
I'll bring it by later this week when I'm back in town and we can run a test. This should tell us what the actual regulated voltage is coming out of the powerbox under loaded conditions.
I read somewhere some time ago that increased supply voltage to servos reduces the neutral deadband of the servo making it more sensitive around neutral. Problem is I can't remember or be sure of the source and it may only apply to analogue and not digital servos.
Is the voltage setting of the 40/24 adjustable?
PaulD
