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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › A question on servo life?
11-16-2017 01:09 PM  26 months ago


Cedar Rapids, IA

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I have a JR MPH83GWV tail servo that works fine BECAUSE the reference is actually the gyro sensor and not the pot. It is not immune to stray magnetic fields - refrigerator magnets.
Not totally accurate on your JR servo working fine because the reference is inside the gyro and not dependent upon the pot (your servo uses a hall-effect feedback element instead of a pot). Position control is no different than any other servo on the market.

Your magic servo is one of many servos using hall-effect sensors as the position feedback element. The gyro sensor does nothing other than output the usual 1 to 2 msec wide pulse that most other gyros and receivers output for servos to use as the position controlling signal.

ALL servos use the signal from the outside whether it be from a gyro or just another mundane receiver channel output as their position reference.

All RC servos include an internal circuit which generates a variable-width pulse generator. The width of the pulse is determined by a feedback element whose input shaft is slaved to the gear train and whose output is dependent upon the position of the input shaft.

Whether the sensing element is a pot, hall-effect sensor, variable capacitor, or a masked LED/Ooptocoupler, its output is used to create a pulse whose width varies with servo output position.

The guts of the servo simply drive the servo motor until the servo's internal pulse width matches that of the incoming pulse.

* Making the World Better -- One Helicopter at a time! *

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11-16-2017 01:51 PM  26 months ago


Monson Ma. USA

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Just like jack332 said at the beginning of your post. You never know. I have had new expensive servos go in one or two flights and cheep servos go for years. Make your best choice and go fly. Some good explanations here.
11-16-2017 03:11 PM  26 months ago

rrElite Veteran

Ottawa, Ontario

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💎Sustaining Member
I have had cheap servos go bad and expensive ones as well.
Electronics are in nature similar to the life span of a light bulb.
You never know how much time/light is left in it.
spending time, paying attention
11-16-2017 11:30 PM  26 months ago



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Especially when bought used.....Logo 600SXs, 800XX, TDR IIs
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11-17-2017 07:29 PM  26 months ago
Andy from Sandy

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Bedfordshire, UK

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Remember the first batch of Align 815s?

I have seen pilots walking out to the flight line stop and come back as one or more of the servos just stopped working.

I sold a set of Futaba BLS451s that are now around 9 years old and still working fine. Remember we were told that they were car servos and not for helicopter use?
11-20-2017 11:53 AM  26 months ago
Four Stroker

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I bought enough BLS451's to last the rest of my life when they were being DISCONTINUED. They were about $80 delivered. I have over 1000 flights on one set and they are like new. I replaced the first plastic gear and that took out all of the slop! Cheap. On the other hand, I had three BLS254's go bad. The motor started squealing due to dry bearing. Still worked well enough not to crash. I necropsied one of them and oiled the bearing. Good as new. Unfortunately, the bearing is under the circuit board and too damn much trouble to fix.
11-20-2017 12:42 PM  26 months ago
Dan Minick

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Columbus, WI

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I have had newer servo's fail for no apparent reason. it just stopped working. and I was using the correct voltage.
Its called quality control, and the lack of it.
Team Synergy, Team FBL Rotors-------if its not will be!
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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › A question on servo life?
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