Hello.
We bought 15 JR8611A servo's for 3x 50cc klasse airplanes.
2 airplanes fly now and we already have locked-up 2 servo's in less then 5 flights!!!
1 on the aileron of my buddy's friend, one on my rudder.
They still work but if the power is off, you can not turn the servo by hand.
Ofcourse this is not acceptable.
I have 8 old JR8611 in my Extra 2.6 and except of the enormous amount of play in the gear they work after 130 flights still ok.
I can see what the problem is, especially on the aileron servo's.
Due to the excessive play in the gear of the servo together with the (not) "improved motor" in the servo's of the JR8611A, the motor will burn out due to vibrations.
In my opinion JR has a serious problem with there servo's.
Since I have this problem, I spend a couple of hours behind the computer and investigate on the internet if there are more people with this problem.
I am completely shocked!!!!!!!!
For years and years Hitec was the servo that locked -up and JR were the servo's of the champions.
I see that times are changed. I see hardly no reports of problems with the new Hitec 5955TG and A LOT of reports of the same problem I have with the JR8611A.
JR have there name and I also am very loyal to the brand JR but I am going to try the Hitec 5955TG.
There is simply no play in that servo, I feeled it with my hand and it is at least factor 10 less the the JR8611A!!!
Ofcourse we are dissapointed, we invested 1500 dollar in servo's and we can "throw them away".
I hope JR is not arrogant and will recognice this problem.
They have to develop Titanium Gear otherwise a lot of loyal JR users will not be loyal anymore!!!!!

The number of problems with the 8611A has been extremely low. I think you are seeing a difference in the number of servos out there, the 8611A is an incredibly popular servo. In addition, claims on the internet can only be taken at face value, there is no way to know if the problem is legitimate or if it was a user induced problem. Problems with the 8611A have been very low and it is a very good servo. I'm sorry to hear that you had problems, but our service center is here to support you. I personally have MANY 8611A's with no problems, and many users are the same way.

Hello Danny.

Sorry if I over react but this year a lot of new equipment has let me down.
The biggest problems are the ailerons.
I use Airwild 1.25" servo arms, tight ball links and my resolution is really high. (>130% each side).
So the only slop is the servo gear slop and nothing else.
If the power is on the servo, I can wiggle the servo's almost a 1/2 inch!!!!!
Together with a straight mounted one cilinder 3W50i CS the ailerons vibrates (induces vibrations) like hell!!!
I am an aircraft maintenance engineer, so I have some technical background.
Vibrations on a control surface ( flutter or engines vibrations) is the biggest load on a servo, period.
I think the new "improved" motor in the 8611A is not up to this task.
Ofcourse 8611A are overkill on any 50cc class airplane but the airloads are not the problem, the vibrations are.
If the gearlash is less, the induces vibrations will be less.
Are those 8611A bad??
No they are good I suppose but I think in other applications like jets or multi cilinder aircrafts wich vibrates less.

The motor in the 8611A is more than up to the task, and the gear trains are very good. Metal gear servos must have play in the gear train or they will lock up. But the 8611/8611A gear train is very good. I have not had any problems with the 8611A. If you have 1/2" play in the system, I would guess the arm fit is not very good on the servo.

Hello Danny.

No the servo arm is a very tight airwild alumium one (1.25 inch), the ball links are the very tight 3W ones.
The only play is the gearslop in the servo.
Yesterday the third servo on my friends model locked-up.
That makes 3 servo failures in 25 flights.
I have replaced my brand new JR8611A for the Hitec 5955 TITANIUM GEAR, what an enormous improvemend.
NO gearslop at all, ailerons stays vibration free, servo is equiped with a aluminium heatsink, runs very smooth.
Please don't get me wrong, I am still a JR fan but not anymore of there servo's.
I find it quit arrogant to say that the "gear of the 8611A is really good" and "the number of problems with the 8611A has been extremely low".
If you just fill in "8611A" in the search option of different kinds of forums, I see a lot of people with the same experience I have.
I will buy the JR servo's again if they replace the gear for a titanium one!!

I'm sorry you feel that way.

Hello Danny.

I am not so crazy after all!!![sm=spinnyeyes.gif]
http://www.horizonhobby.com/Products...odID=JRPS8611A
I have 4 almost brand new 8611A NOT MORE IN USE, that I don't thrust because already 3 of these 8611A fried-up.
You sayed more or less that it was a "users-error" and not the servo's.
I am quit happy Horizon-Hobby came with this announcement.
Although I did the test of the 4 servo's Horizon Hobby mentioned and it pased it, I don't thrust them.
What are we going to do with this situation?

Danny, I'm sure you're man enough to both apologize to the guy and to replace his servos.

First of all, you will need to contact your local JR service facilty for assistance. As you stated however, the servos past the test on the bulletin so there is nothing needed to do outside of flying.

There is a problem with the 8611A.
If you load it to the maximum torque it will burn out the motor very quickly. Fortunately its very hard to get it to the maximum torque. About the only way is to get it stalled in some way.
The 5955 uses the same motor but the amplifier limits the current to a safe value. On the other hand the 5955 will not produce the torque they claim for it.