Capt Jim

My Feedback: (168)

At the local hobby shop I have purchased a pair of JR RT88 retract servos for a new Hangar 9 P-51 -60 Mustang.
The servos of course were brand new in the box, and carefully installed as per instructions.
After installation, they cycled perhaps 8 to 12 times during the set-up session, checking for wheel well clearances etc...which were fine and without any obstruction, and then for no apparent reason both of the servos stopped functioning completely.
Using a Spektrum DX7 tx, Rx is a R7000 running on a fully charged 6 volt NiCd rx battery. All other servos perform flawlessly, and an alternate servo was plugged into the rx retract port to test it's operation, and the test servo worked as it should.
No extensions are involved, the servos are being plugged directly into the rx retract port.
I have even tried them on a 4.8 volt battery with no better results.
It appears that these servos have simply gone bad quite early on in their life cycle. I have checked the bulletins for any news of issues with these, but found nothing. At this time the entire project is on hold. Please advise ASAP.
Thank you.
jim

codimasta

My Feedback: (89)

Check the voltage that is recommended for the servo...had that problem with another JR retract servo..it was rated at 4.8v...I was using 6.0 v pack...send them back to
Horizon..they did replace the servo...with a warning not to use 6.0v...good luck

Capt Jim

My Feedback: (168)

The box the JR RT88 servo comes in gives specs for speed and torque at both 4.8 and 6 volts.
Wouldn't you agree that a reasonable person would take from that printed statement that 6 volts is OK to apply to this servo? 8>)
I am aware of some servos not operating at 6 volts, but these particular servos were purchased specifically for a 6 volt application.
Additionally, I have found that earlier JR retract servos would NOT function at all on 6 volts, yet would immediately work normally when the 6 volt pack is removed and a 4.8 volt pack is used in its place. Such was not the case with both of these RT88's.
A bad batch???. It is a bit worrisome. I am hoping for a quick resolution from the folks at JR...via this forum.
jim

BuschBarber

My Feedback: (2)

I have a Hangar 9 P47-150. I originally used the RT88 Retract servos but after a short time, one of the gears failed. I also set the plane Upside Down and could not put the gear down because Gravity was stronger than the RT88's. There is a separate servo for each Retract Mechanism.

I switched to the 791 Retract servos, which had much more power, but they were not designed to work properly at 6v. I use LiPo Rx batteries with a 5v Regulator and all is well.

I imagine that the RT88 servos are OK for a 60 size plane.

Capt Jim

My Feedback: (168)

It's been nearly two weeks since posting this issue, and not a word from JR or their support folks. I had expected some comments from them...certainly the typical offer to replace them with good ones. This is quite suspicious. Now another gentleman reports issues with the JR RT88 retract servo. I will attempt to get a cash refund, and look elsewhere for a reliable retract servo. I find it disappointing to have an honest issue like this sour ones respect for a prominent manufacturer.

BuschBarber

My Feedback: (2)

Have you tried calling Horizon? They no longer reply to posts on RCU since Ask Danny was closed.

The JR 791 servo has plenty of Torque. More than any other Retract servo. It is very rugged.

Ricky Blade

hello, i just purchased a h9 p-47 81" at a swap meet as a project (partialy built). i'm not sure if it is considered a 180 but the 791 servos are the same recommended. have you found any optional servo drop in fit? any pointers on building / special attention givin to... ect? i'm using a jr 9303 2.4 radio and zenoah g26ei. any pointers would be greatly appreciated. thanks ricky.

Capt Jim

My Feedback: (168)

Hey Ricky...I can't tell you anything additional about the servos. We just went out and bought two more new ones and these seem to be working OK....so far. Good luck on your P-47. I had a Top Flite P-47 that I built from a kit...I used a Zenoah G-62 in it with the spring starter option. It was a sweet plane. I sold it a year ago. I sure do miss that plane.
If you ever get down Boca way...look me up...come fly with us at our field....600 foot paved runway.
Jim

Ricky Blade

hey Jim. i have flown at your beautiful field on a few trips south! Walt got me back into the hobby. i will look you up next time i visit. ricky