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Old May 10, 2011, 05:32 PM
A.T. is offline
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Digital Servo - Why They Burnout

Originally Posted by koolkiwikat View Post
Help, I sold this servo to a friend of a friend, servo was sold new, apparently the damage happened within a few minutes or use, what would of caused the damage pictured?
Servo was rated at 16kg's @ 6V, was it overloaded? power reversed?, just a crap servo?It was powered by a 6v batt pack, no BEC used thru the receiver
Any ideas appreciated
Answered NZ Parkflyers
"Just checked negative cable is fine nothing punched thru, it was mounted, I pulled it apart to inspect, gear travel is fine as I thought it may of gotten jammed passed its furthest travel...but it was centred"

. Gear train is not a good indicator of a jammed servo. This especially with digital which can burn out within seconds if control surface (ailerons/elevator/stearing arm et al) is binding with excess glue or hinges out of alignment or not able to travel, for any reason, as far as the servo is trying to push it.
. What gauge of wire was used for leads (+) & (-) to the servo?
Insufficient wire gauge or poor connections/soldering can yield significant IR losses which results in major voltage drops at the servo. Most analogue servos continue to work with a major voltage drop, albeit with lower torque and slower transit speed, while the digital servo's internal microcontroller will often reset during similar voltage drops. The instantaneous current demands seen with a digital servos are often much higher than their analog counterparts = another probable cause of burnout.
Digital Servo Burnout - further similar comment.
Digital Servo Setup - also refers.
Digital servo burnout - Futaba answers, includes:
"Q.What can I do to ensure long life of my digital servos?
A. The number one concern is tight linkages which have absolutely no binding, stiffness, or friction. Because digital servos are always working to hold in position at full strength, if the servo has a point it has to fight in the linkage it will literally burn itself out 'hunting' to try to hold its position. Slop at the neutral position is a very common problem where a standard servo wouldn't notice it but a digital servo will work very hard to try to hold the rod in position and will drain your batteries more quickly and eventually burn up the motor."

Digital Servo Burnout - JR answers, caution with Voltage.
Digital servo burnout - Sanwa(Airtronics) answers caution re Voltage and need to use regulator with Lipo.

Tip to Prevent Digital Servo Burnout
" Recently, we encountered a couple of cases regarding servo burnout including DS410/410M, DS420, SSD-101, and SSD-102. After further investigation, we realized most of them are not due to product defect but installation problem. According to the symptom from these cases, the servo was stuck and heated up after power on. They were all installed and for test first. We found those servos were fixed with extra washers or spacers which actually intruded the upper case into the gear set inside. Here comes some tips to prevent this kind of unexpected servo damage: 1. Please check and make sure the servo is ok (not defective) before installation. 2. If you will use washer/spacer to secure the servo in position, please make sure they are not oversize (won't touch the lateral of upper case). 3. If you find the servo bind and heat up in any case, please disconnect the power immediately.
This article was published on Friday 02 October, 2009. "

Digital Servo Burnout - EPA extended to far
"They burnt out while I was programming servo movement with my computer radio and the battery got really low. Then all of a sudden they give a little blip and burn out."
The computer radio trim range will over shot the servo max travel! Tha will cause the servo turn to dead end and stuck! If you keep going on to move more, the stall current of motor will cause amp and motor burn!
The GWS servo only good for 1.0~2.0ms pulse width. Over this range may cause damage to servos. (continued post #17 & #18) =
Although GWS spec 1.0~2.0ms, during production line QC test, we still have some safety range to make sure every one exactly safe for user in case the old TX pulse range off-set after long years used. But for those computer radio you may set end point up to 50%, that's way too far away to our servo specs designed.
Many of the old timer system come with different pulse width range! Futaba old G and before by 1.3ms center point and 0.5ms shift. Kraft 1.4ms, Kraft sport 1.85ms, old Multiplex 1.8ms, and Japan Digicon even small as 1.0ms But a 1.5ms should be main trend for years- GWS4CEO"

. Was the correct brand of servo arm being used?
Whilst many may appear to be interchangeable, Aftermarket or other brand may screw right down
on top of the servo case, appear to work for a short period and then servo burns out.
. Have found this to be a direct cause of servo burnout with several "servo saver" and especially some aftermarket horns being used without user checking for a clear gap between bottom of horn and top of case.
. Before Installation in model.

Plug servo into RX and Test Servo is functioning correctly. Center trims so as to position servo arm at 90 degrees (few exceptions e.g. switched retracts & some flaps) and recheck operation is still free with gap between base of horn and servo case.

. Servo - Horn arm Spline Count and Inter Brand Compatibility
. Servo - Installation - Correct Mounting & Tips for longer life. with pictures
. Servo Not Centering properly_How to Correct.pdf

refer also
Servo - Operating Voltage Range - (Futaba) usuage with NiMH, Lipol, LiFe & A123 batteries. #01
Servo - Operating Voltage Range - (Futaba) usuage with NiMH, Lipol & A123 batteries. #02
Servo - Operating Voltage Range - (Hitec) usuage with NiMH, Lipol & A123 batteries.
Servo - Operating Voltage Range - Hitec Pre-HV Servos useable with unregulated 2S Lipo
Servo - Operating Voltage Range - (JR/Spektrum) - max 6.0v fixed.
Servo - Operating Voltage Range - (Sanwa/Airtronics) with NiMH, Lipol, LiFe & A123 batteries.
and more under
Alan's Hobby, Model & RC FAQ Web Links (quick search = Ctrl+F)

NZ Parkflyers Post #9 has a good solution for existing servo.

Alan T.
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Last edited by A.T.; May 18, 2013 at 06:32 PM. Reason: update url
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