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Old 10-17-2016, 03:45 PM
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Question
NXB 8921 Servos

Those that are using the NXB8921 Brushless High Torque XBus Servo,,, curious to know your thoughts about them?

thanks in advance, BV
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Old 10-17-2016, 04:34 PM
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Simply put,they are the best servo JR has made to date. They are crazy efficient and with the aluminum case there is practically no wear on the servo. I've been running them on my freestyle/IMAC plane (over 200 flights) with 2 inch arms and the servos are still tight.
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Old 10-17-2016, 04:47 PM
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I have a set on a 35% also. They are everything Santiago says
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Old 10-17-2016, 05:30 PM
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What about the JR NX8921, its more in my budget.
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Old 10-17-2016, 05:52 PM
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Quote:
Originally Posted by 5150flyer View Post
What about the JR NX8921, its more in my budget.
That servo has been discontinued and replaced with the NXB8921. If you need to save a few $$ then go with the NX6421 also a very robust servo gear train. I have several of them and the gears are very good.
Jeff
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Old 10-17-2016, 06:01 PM
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Quote:
Originally Posted by 5150flyer View Post
What about the JR NX8921, its more in my budget.
The direct replacement for the NX8921 is the NX8931. http://www.jramericas.com/235224/JRPSNX8931/?pcat=1671
I have been running 8921s all year and would echo the previous comments.
t
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Old 10-17-2016, 08:31 PM
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are those NX8931's all metal case, to include the top case?
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Old 10-17-2016, 08:47 PM
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Nope!
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Old 10-17-2016, 10:11 PM
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Does this have the linear hall sensor instead of the standard pot? The pot wear out causes jitter a center over time.
I've had the MPH83T linear hall sensor servos in a 100cc Yak for 3 yrs, and they have no jitter and virtually no gear wear. I think the MPH83T is discountinued.
The linear hall sensor is a good innovation.....i'm surprised they discontinued it.
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Old 10-17-2016, 10:40 PM
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I previously used the JR MPH83T Linear Hall Servos in an Aeroworks 60cc Freestyle with great success. I fly 3D & precision. On the 3rd day the JR NXB8921 servos became available, I decided to give them a try and purchased (5) of them from JR Americas. I have almost 100 flights on them in my Freestyle and have been very happy with their precision & torque on 7.4 volts. I have had a number of excellent 3D pilots fly my airplane with these servos and a common statement with all of them is "What servos do you have in your airplane? They are very precise and powerful". They ran flawlessly in 95 degree heat and power large control surfaces that have up to 65 degrees of throw. The gear train is still tight. They have low battery drain. I love the soft start feature and how quiet they are. Simply put, I am very happy with the JR NXB8921 servos and agree with Santiago - these are the best servos JR has ever made.
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Old 10-27-2016, 09:37 PM
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anyone know where this servo can be purchased?
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Old 10-27-2016, 10:37 PM
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I purchased and just received (5) more of the JR NXB8921 servos directly from JR Americas - www.jramericas.com.
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Old 10-27-2016, 10:40 PM
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To answer Ijagnna's question, the JR NXB8921 servos do utilize a pot.
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Old 10-28-2016, 07:12 AM
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Yes they do use a pot. A lot is not what causes jittering tho. If you do get the jittering you can go in and change the programming on the DGain in the servo programming and tune that out. It is easy to do. I am going to see if I can make a video to show how to do this. There is a thread about chatter I was gonna put it on
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Old 10-28-2016, 09:47 AM
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I thought the linear hall sensor was a real innovation.
Changing the gain or deadband can help alleviate the issue somewhat but also comes with some drawbacks. The pot will wear out over time.
I don't understand why JR dropped this innovation.
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