Corona DS-939MG - Mini Servo


Modulation: Digital
Torque: 4.8V: 34.70 oz-in (2.50 kg-cm)
Speed: 4.8V: 0.16 sec/60°
Weight: 0.44 oz (12.5 g)
Dimensions: Length:0.89 in (22.6 mm)
Width:0.45 in (11.4 mm)
Height:0.97 in (24.6 mm)
Motor Type: Brushed
Gear Type: Metal
Rotation/Support: Single Bearing
Rotational Range: (add)
Pulse Cycle: (add)
Pulse Width: (add)
Connector Type: JR
Corona DS-939MG
Brand: Corona
Product Number: (add)
Typical Price: 8.45 USD
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Reviews of Corona DS-939MG (4)

  • Rating:

    Application(s): Powered aircraft, gliders, NOT helis.

    Comments: I run it from a 5v bec, a 4 or 5 cell nicad pack, or a 2 cell LiFe (6+ volts).

    So far, the only problem has been that the output bearing seems to be of low quality, as they develop some slop fairly quickly. A friend of mine prefers the 928, which is an analog, plastic gear servo with, I believe, a bushing instead of a bearing. His comment was that the digital bearing servos got sloppy fairly quickly.

    The bearing is a 5x8x2. I've been able to find a 5x8x2.5 from RcBearings, but not a 5x8x2, but I have not really tried to locate the correct size at this time. I may just try a 5x8x2.5 and see if it works.

    Aside from the radial play in the shaft, they seem robust. There's some backlash, but nothing unusual for a metal gear servo.

    Despite some other reports, I've had no problems running them on 6v, including using a 2 cell LiFe. I'm using them for the ailerons in my Acromaster, and their holding up well. Better than the HS55's the previous owner had used.

  • Rating:

    Application(s): EP Airplane & 450 Heli

    Comments: I have been using the CORONA 939MG on my 450 Cyclic and all over my Dynam T-28 Trojan control surfaces for over a year now.

    So far non has failed on all my applications. It is powered by a Turnigy 5Amp UBEC on 5volts.

    The gears are a bit noisy at times specially when binding occurs, its actually a good sign because it lets you know about the bind and or excessive loads.

    Weighs a little more than most plastic 9g servos but gears are more reliable on any application.

    I recommend this for light aircrafts with light to medium loads. Its a bit slow for 450 heli cyclics but does the job anyway.

  • Rating:

    Application(s): rc plane

    Comments: it is very good servo as long as you are not using it on 6V. I have heard about strenge situations wen it was used on 6V. I am using it on 5V and there is no problem with at all.

  • Rating:

    Application(s): Servos installed in 2m Glider

    Comments: When setting up the servos in the wings, I had two servos fail. One Aileron and one Flap servo. The Aileron servo jammed solid, probably gears, and the Flap servo tatally burned out, melting the servo case and servo lead. I am running 6v electrics, has anybody else had the same problems? I have used Corona receivers for a couple of years without any problems.

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