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Technical Specifications
Last Updated: 2026-09-13| Identity | |
| Brand |  |
| Product Number | DS939MG |
| Category | Hobby |
| Discontinued | Yes |
| Performance | |
| Torque |
6.1V
37.51 oz-in
2.70 kg-cm
0.3 N-m
4.8V
34.73 oz-in
2.50 kg-cm
0.2 N-m
Above Average
|
| Speed |
6.0V
0.13 sec/60°
461.5 deg/s
76.9 RPM
4.8V
0.14 sec/60°
428.6 deg/s
71.4 RPM
Below Average
|
| Running Current |
6.0V
0.240 A
240 mA
4.8V
0.200 A
200 mA
Below Average
|
| Physical | |
| Weight | 0.44 oz12.5 gAverage |
| Dimensions |
L 0.886 in W 0.453 in H 0.969 in L 22.5 mm W 11.5 mm H 24.6 mm |
| Case Material | Plastic |
| Drivetrain | |
| Motor Type | Coreless |
| Gears | Metal |
| Gear Spline/Teeth | 21 T |
| Rotation Mode | Positional |
| Rotation/Support | Single Bearing |
| Control & Signal | |
| Modulation | Digital |
| Rotational Range | 80° |
| Pulse Width | 1100-1900 µs |
| Neutral Position | 1500 µs |
| Dead Band | 3 µs |
| Angle Sensor | Potentiometer |
| Control System | PWM |
| Programmable | No |
| Electrical & Environment | |
| Operating Voltage | 4.8–6 V |
| Power Source | External |
| Regulator Type | Direct |
| Temperature | -20–60 °C-4–140 °F |
| Connectivity | |
| Connector | JR (Universal) |
| Wire Length | 215 mm8.46 in |
| Origin | |
| Country of Origin | China |
Disclaimer: Most data is sourced from the manufacturer. Some data is sourced from our loyal community and with the help of AI. We aim for accuracy but are not responsible for inaccurate information.
Class Comparison
| Torque | Above Average Stronger than 69% of 328 Digital Micro servos at 4.8V |
| Speed | Below Average Faster than 24% of 328 Digital Micro servos at 4.8V |
| Weight | Average Lighter than 38% of 620 Digital Micro servos |
| Running Current | Below Average Lower draw than 31% of 53 Digital Micro servos at 4.8V |
Performance Analysis
| Shaft Power | 0.46 W |
| Power Density | 1.179 W/in³ More power-dense than 24% of 590 Digital Micro servos |
| Torque Density | 2.7784 oz-in/g Stronger than 64% of 327 Digital Micro servos |
| Torque-to-Volume Ratio | 89.30 oz-in/in³ Denser torque than 65% of 327 Digital Micro servos |
| Speed-to-Weight | 0.57143 (1/sec·g) Faster than 29% of 327 Digital Micro servos |
| Speed-Torque Trade-off | 4.86 Better balanced than 74% of 327 Digital Micro servos |
| Speed Gain per Volt | 6.40%/V More voltage-responsive (speed) than 2% of 273 Digital Micro servos |
| Voltage Range Width | 1.2 V Wider voltage range than 44% of 511 Digital Micro servos |
| Dead-Band-to-Pulse-Width Ratio | 0.0038 Finer dead band than 7% of 189 Digital Micro servos |
Notes
This servo was replaced by the DS939MG-2.
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Reviews (4)
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sorenlaf
September 26, 2013Application(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.
Dongskie
January 6, 2012Application(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.
kamelasty
May 25, 2010Application(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.
14MZ Flyer
December 24, 2009Application(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.