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Old Jul 27, 2014, 07:51 PM
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servo shelf life

I just opened 6 new-in-package Proline servos by AMC and found that none of them worked!
I could see one or two failing but all six? What the heck.
These are the Kraft servos that Proline used with deans connectors.
Anyone know the secret?
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Old Jul 27, 2014, 07:59 PM
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Are they 4 wire? LOL
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Old Jul 27, 2014, 08:52 PM
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No, just3 pin deans connectors
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Old Jul 27, 2014, 10:30 PM
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Joined Feb 2006
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As I recall, Proline servos were not compatible with other RC systems because they used negative input pulses. Specifically, though they used kraft mechanics, they would not work with Kraft receivers, which used positive pulses like most other radios

To test or use them you would have to build adapters.

Servos don't have any particular shelf life. I have servos from the 1970s and all I have tested still work.
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Last edited by Daedalus66; Jul 27, 2014 at 10:38 PM.
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Old Jul 28, 2014, 09:45 AM
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I used those ProLine servo's for years. You have to invert the pulse from the receiver to the servos to use them with modern Tx/Rx's though. That is rather combers um to do (takes a bit of electronics) but if you have the know how and time, it works.
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Old Jul 28, 2014, 10:34 AM
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Pulse inverters. Ace RC used to make them but they are out of business. Try EMS ELECTRONICS. Mark Schwing. He knows about them things!

Mike Lee
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Old Aug 09, 2014, 05:22 PM
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I was testing them with a servosizer so shift shouldn't be a factor.
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Old Aug 09, 2014, 07:47 PM
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What is a "servosizer"? Can it change the PWM polarity?
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Old Aug 09, 2014, 08:11 PM
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Servo exerciser. Just a servo driver that goes back and forth.

Not usually.

Andy
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Old Aug 11, 2014, 04:17 PM
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Rodney---------
explain a little further please. have been using servos (including ProLine) for a long time and I have never heard of this.
What is PWM polarity Ivanc?
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Old Aug 12, 2014, 09:50 AM
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Quote:
Originally Posted by Rodney View Post
I used those ProLine servo's for years. You have to invert the pulse from the receiver to the servos to use them with modern Tx/Rx's though. That is rather combers um to do (takes a bit of electronics) but if you have the know how and time, it works.
Jim Fosgate lives down the road (actually up the mountain) from me - he added the "inverter " to mine a few years back.
he still flies a Proline (along with Spektrum)
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Old Aug 12, 2014, 10:15 AM
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Most if not all current servos require a positive going pulse on the signal line that has a duration of 0.5 to 1.5 milliseconds every 20 milliseconds. The old Proline used a negative going pulse of the same duration and frame rate so, to use a modern input with the old Proline servo, you need to invert that signal on the signal line. By negative going, I mean that the signal line was held at the positive voltage on the servo bus and would be dropped to ground or zero volts for that 0.5 to 1.5 millisecond signal pulse.
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Old Aug 12, 2014, 10:42 AM
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Quote:
Originally Posted by Rodney View Post
Most if not all current servos require a positive going pulse on the signal line that has a duration of 0.5 to 1.5 milliseconds every 20 milliseconds. The old Proline used a negative going pulse of the same duration and frame rate so, to use a modern input with the old Proline servo, you need to invert that signal on the signal line. By negative going, I mean that the signal line was held at the positive voltage on the servo bus and would be dropped to ground or zero volts for that 0.5 to 1.5 millisecond signal pulse.
yup
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