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#1
14-03-2013
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Savox Servo Problems
I'm having bother with my savox servo or maybe something else?
Running Spectrum module and receiver, LRP SXX ver 2, savox 1251. the sxx and savox are new. The first savox stopped working and it was replaced, the second had all but stopped working, very slowly and jerky. Any thoughts anyone?? Anyone know of any conflicts between the above. Keith 
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#3
14-03-2013
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Mr Emily, there was also a batch problem with Version 2 SXX's that dropped out the BEC. Might be worth a word with Rich Johnson at SMD? He covers off the LRP warranty stuff. We had 2 SXX's which had the BEC problem.
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#4
14-03-2013
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BEC in the LRP...
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Team Yokomo - YZ-2CAL3 | YZ-2DTM3 | YZ-4SF2 | YZ-2T | YZ-2DTM Worlds | YZ-2DTM x2 | YRX-12 x2 ------------------------------------------------------------------------------------------------------------------- 10electric | Batley Buggy Club | YORCC | RHR | MB Models ---------------------------------------------------------------------------------------------------------------
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#6
17-03-2013
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Try a capacitor so the servo doesn't draw excessive power from the BEC circuit. Spectrum offer their own but I'm sure other people do them too.
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#7
17-03-2013
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there have been problems at our club with savox servo's running on bec, drawing too much current and causing receivers to drop into failsafe or servo's to misbehave. good size capacitor might help (has for some) other than that its an external bec or a different servo. 3A bec circuits just dont seem to be able to cope. some older brushless systems caused problems with spectrum due to the receiver not liking the speed controls drive frequency, but i doubt any modern gear will be affected by this
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#8
18-03-2013
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A capacitor fitted to a spare socket on the receiver should fix it. Any 4700uF 10V or better cap should do it. Savox and spektrum have caused me issues before. I did some tests and traced it down to poor BEC design compounded by savox power hunger.
Not all BEC are created equal. Some are better than others. From the ones I’ve tested LRP come out well, while cheapy chinese Speedos not so good. Results: Both BEC specified at 3A rating. And yes they both worked perfectly at 3A. However a savox can draw over 3.5A for very short periods this can cause BEC to fall over and drop its output volts so the receiver resets and causes glitches. ToroPro 120A BEC rated 3A tested with electronic load set to 3.5A for 500uS duration. (tek00013.jpg) pale blue is load current, dark blue is BEC output voltage. You can see the output voltage dropping below 4V this is where a spectrum receiver will fall over. LRP Sphere DEC rated at 3A tested with electronic load set to 3.5A for 500uS duration. (tek00014.jpg) pale blue is load current, dark blue is BEC output voltage. You can see the output voltage does not drop below 5V all should be well with this The function of the capacitor is to supply the energy to fill in the voltage drop when the load is high. Basically smoothing out the BEC voltage and not have nasty drops like in tek00013.jpg
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Team Gregg: Getting in the way since 2008
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