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Old 03-21-2012, 04:28 AM   #1
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Default Help, Car shuts off intermittenly with new Savox servo

Both my Losi SCT and SCTE shuts off intermittenly with new Savox servo.
Problem - when driving it's like I lose radio signal - however, when this happens, the ESC still shows red lights,
the receiver loses green light.

Details - happens with both my Spektrum transmitters, SR300 and SR3000 receiver, tekin RX8 and RS Pro, mutlitple batteries, mnultiple tekin motors in both cars, new transmitter batteries and has resolders motor connections, battery and speed control connections and even changed leads to the ESC plug to receiver.

SCTE - I purchased used and has Savox servo -
XXX-SCT - I just purchased brand new Savox SC-1258TG Standard Digital "High Speed" Titanium Gear Servo and installed and problem started

However, I put the original Losi servo in ...now no problem.

Any thoughts or suggestions on this?

Thanks for your help, very frustrated and would like to race this weekend
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Old 03-21-2012, 04:37 AM   #2
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you need a capacitor for the receiver, costs about $5 and will solve your problem. spektrum sells one, don't remember the part number off the top of my head but your lhs should have some.
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Old 03-21-2012, 04:39 AM   #3
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The Spektrum receivers have problems supporting high draw servos. I had same problem. You need to run a Spektrum or other power capacitor plugged into your receiver bat port.
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Old 03-21-2012, 04:41 AM   #4
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Matt typed faster than I did.
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Old 03-21-2012, 05:21 AM   #5
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http://www.horizonhobby.com/products...tector-SPM1600
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Old 03-21-2012, 05:55 AM   #6
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thanks for your help, ordered 3 and they will be here in two days, ill report back
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Old 03-21-2012, 05:19 PM   #7
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It's really a good idea for us all to run a cap.

Spektrum receivers do what's called a brownout at 3.5v or below. I have had a meter on them and increased voltage in the esc only to have a lower voltage at the rec. They really are a pain in the butt
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Old 03-22-2012, 07:41 AM   #8
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If the cap doesn't work you'll have to add an external BEC. Castle makes one for about $25 and that will definitely do the trick
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Old 03-22-2012, 11:58 AM   #9
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i had the same problem about a month ago. i bought the novak glitch buster capacitor, no problems since.

wish i got the spektrum one though, its half the price
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Old 03-22-2012, 12:11 PM   #10
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You can just go to any electronics store and get a capacitor with the same capabilities, and solder it to an old servo plug. Costs a dollar or so, and the "glitch busters" are nothing else.
Also, for a BEC that can handle the sav÷x servos just fine, hobbyking has a 3A BEC for 4 bucks (7 in the EU warehouse) that is light (low shipping cost) and works great, if you can wait a bit longer for it to arrive (HK and EU warehouse only).
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Old 03-22-2012, 12:28 PM   #11
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I put a castle BEC in my VE8 to run a savox sc 1258. If you go the BEC route, there's a couple diff ways to hook them up..search my name. Id find them for ya, but i'm on my phone.
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Old 03-22-2012, 04:40 PM   #12
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Has anyone asked why the Savox stuff seems so inefficient?
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Old 03-22-2012, 04:55 PM   #13
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Quote:
Originally Posted by Davidka View Post
Has anyone asked why the Savox stuff seems so inefficient?
+1
Although it seems to be trendier to blame it on a receiver that draws what, something like 10 or 20mA?
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Old 03-22-2012, 05:02 PM   #14
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I could see it if could be determined that the average BEC were making enough power and the RX was some sort of "bottleneck" but then it doesn't explain why two 200+ oz servos by anyone else in a truggy do just fine.
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Old 03-22-2012, 05:40 PM   #15
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Quote:
Originally Posted by Davidka View Post
Has anyone asked why the Savox stuff seems so inefficient?
They aren't inefficient, they just draw power in a very nasty way. They have a very high starting current and they draw their current in a very spiky fashion. I put my 1256 on a o-scope and work and compared it to other servos. My guess is that they don't put any kind of filtering in the servo and other companies do. When I tested the 1256 I was seeing peak currents that were around 8A. The bottle neck is the system is the wire that connects the ESC to the receiver. With high current spikes you also gets large voltage drops due to series resistance. This is further aggravated by today's modern receivers which do not have internal BEC circuits and the voltage regulators that are used to power the processor do not have much of a hold up cap on them.
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