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Old Oct 10, 2013, 06:34 AM
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Joined Oct 2013
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Hitec HS 785 HB Sail Servo

Hi guys
I recently bought a Hitec HS 785HB sail servo for my 1m sailboat.
The problem is that if there is even the slightest tension on the sheets it won't reach the end points.
I've tested it with 4.8v and 6v packs and no difference.
I've also tested it with two different radio systems (Spektrum and Turnigy) with the same results.
This servo is meant to be rated at 13kg for 6v !
Is this normal ?
Any advice will be greatly appreciated.
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Old Oct 10, 2013, 10:37 AM
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thorsail's Avatar
Chicago , Illinois
Joined Jul 2008
878 Posts
andrew
it ought to work--but a picture is worth a thousand posts--maybe some aspect
of the installation is the problem.I assume you ARE getting the full 3 and a half
turns from stick up to stick down even without line on it ?
we might need a visual on this one........
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Old Oct 10, 2013, 09:36 PM
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Australia, TAS, Penguin
Joined Mar 2012
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@andrewgrinter:
I am running an A Class with two of these winches installed. I have no issue at all with the endpoints being the same all the time, no matter what the load. Running it on 6 volts (5 x NiMH AA).

Perhaps you have a dud servo....?
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Old Oct 11, 2013, 07:25 PM
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Wisconsin
Joined Jun 2007
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I know this sounds silly, but are you sure the batteries you used for testing were good (charged)? I can't count how many times that question came back around to "oh yeah, I guess the pack was dead".

Dave
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Old Oct 11, 2013, 11:21 PM
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Canada, BC, Maple Ridge
Joined Jul 2011
464 Posts
As you changed both Rx and batteries, it sounds like either the winch or its wiring and plug.

If you plug in a standard servo into the winch Channel (port 3), does that work normally and with good force?

Try plugging the 785 into another channel, eg rudder (port 1), now does it work?

Are you running it on a Y cable? eliminate the Y and try direct from the Rx.

John
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Old Oct 12, 2013, 12:45 AM
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Joined Oct 2013
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Hi Guys
Thanks very much to all of you for taking the time to reply.
I will post some pics of the setup this afternoon.
The packs were definitely fully charged.
I have in the meentime bought another servo.
My feeling is also leaning towards a dud servo.
I'll keep you guys posted.
Thanks again for the help.
Enjoy the weekend.
Andy
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Old Oct 15, 2013, 05:33 AM
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Joined Oct 2013
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Hi Guys
Just an update.
I replaced the servo with a new one and reduced the tension on the system.
The new servo operates in exactly the same way as the old one ,so that is not the issue.
Reducing the tension made a difference of about 50% but I'm still not entirely happy. I keep forgetting to take a photo of the setup

Will post pics asap
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