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  1. #1
    RC Racer
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    Sep 2012
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    do I need an external BEC?

    I replaced my dual stock steering servo's with one HiTech HS 7955T and it seems to hum constantly. I've adjusted it several times but it still does it. I read some where that it is recommended to run an external bec. What does the bec do any way? My lights never dim (if that helps).

  2. #2
    RC Turnbuckle Jr. jamann's Avatar
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    Bec supplies power to the rx and in turn the servos.a external does the same but usually does a better job dealing with higher amp draw.Also adjustable voltage output.standard is 6.0 v
    Some servos are capable of higher voltages
    Mine 7955tg has that intermittently,doesn't seem to have affected it though.if your lights are not dimming under load that is a good thing.
    I can't keep lights intact on mine so wouldn't have noticed anyways....lol



    Sent using lipo power
    Last edited by jamann; 11-28-2012 at 04:07 PM.
    Mountains cant stop me
    they have tried

  3. #3
    Marshal ksb51rl's Avatar
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    Hitec 79xx servos are very "talkative." My 7950 has been rather loquacious since June 2010. No problems. Just make sure that it's just normal noise and that there aren't binding issues.
    Alt-248 on the number pad =

  4. #4
    RC Enthusiast
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    May 2012
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    I have the same servo in my revo, recently it conked out. ( motor quit, servo acting all weird)I called castle and they suggested a external BEC. I got one and put it on and wala, everythings back again. Mind you I had been using the stock set up for a couple months with no problems, then wacko it went. I suppose you could get one to have, just run it till ya need it.

  5. #5
    Marshal ksb51rl's Avatar
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    Castle's advice is not surprising. The MMM's BEC is set at 5.5 Volts while the EVX-2's is set at 6.0 Volts. I hope you didn't ditch that servo. I forgot that my servo's amp fried last ?summer? from using it with a ground up external BEC in my ERBE and Hitec repaired (not replaced) it without charge.
    Alt-248 on the number pad =

  6. #6
    RC Racer
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    Nice, I'll look into getting one then, having never bought one I don't know if there is anything I should look for in a BEC?

  7. #7
    Marshal ksb51rl's Avatar
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    Yes: good instructions on how to wire it!
    Check Here.
    Alt-248 on the number pad =

  8. #8
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    No need for an external BEC IMO... Ive run that same servo in an MMM powered ERBE and my Revo GT car with NO issues at all. The humming is, IMO, due to the servo saver not returning the dead centre after you let go of the wheel... so the servo is under a tiny bit of load. Its not a problem and shouldnt require an external BEC. You should try a glitch buster before going to a BEC anyway. They often solve minor issues at a very minimal price.
    Pede, Summit,
    ERBE, Rally,
    Motley Crew, 1SQ

  9. #9
    Marshal ksb51rl's Avatar
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    Agreed, but if the OP were to get one...the CC BEC works very well.
    Alt-248 on the number pad =

  10. #10
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Man, you and me KSB... we just never agree on anything do we
    Pede, Summit,
    ERBE, Rally,
    Motley Crew, 1SQ

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