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[firstime67]

Hi all
I have International One Meter yacht. The sails are controlled via a Hitec HS-785HB winch servo. At present the winch rotates three revolutions with my Futaba 40Mhz T4YF Skysport Transmitter. Can any one tell me how to make it rotate just two revolutions, while maintaining fully available sail stick control? I have the capability to carry out any modification, but need to know the procedure.
Thank you.

[barriew]

Does the Tx have adjustable servo throw?

Barrie

[firstime67]

Hi Barrie

Unfortunately, no. The instruction for the HS-785HB say’s to adjust the throw of the transmitter stick (or the ATV of the sail winch channel),  neither of which are mention in the Futaba manual. At present with the three revolutions of the winch I have an excess of sheet to wind in. I have yet to find out what ATV is.

Regards.
firdtime67.

[BobF]

Hi firstime67,

There is a mod which is fairly straight forwards. Depending on the transmitter, you will require a 5k or 10k miniature linear carbon track potentiometer. This is fitted between the middle terminal of the rudder pot and the circuit board, and is fitted into the transmitter in a convenient place where there is room.

I have a copy of Marine Modelling October 1995, where this is described in full, but at the moment my scanner is not working so I can't email you a copy. I think that I have also seen this mod on the internet, but can't remember the site name though.

Bob

Just remembered that one of the servo manufacturers had a mod that fitted in the servo wire. But again I have no information to hand on who it was. If I can find it I'll post again.

[Faraday's Cage]

Welcome firstime67,

ATV (adjustable travel volume).

Radios with ATV allow you to set how far a servo arm can move from its neutral position to either side. ie 100% travel either side to 0% travel.  In your case, amount of turns on your winch.

Terry.

[barriew]

The mod was mentioned on the old MB site - someone posted a link to their site with an excellent diagram for the mod Bobf mentions. I tried it and it worked, but now only have Txs with ATV. I think it was a fast electrics site, but have just been Googling for 5 mins and can't find it  >:(
Maybe someone can remember the site or poster.

Barrie

[firstime67]

Thanks guys. Looks like there is a light at the end of the tunnel.

Regards.
firstime67.

[Ian Robins]

hi firstime67,

sent you a pdf via e-mail,
this shows how to increase a sail arm  servo rotation from 90 to 180 degrees.
hopefully someone will be able to reverse this for yon

ro88o
NDMBC

[barriew]

Found it!! On this site as well.

Take a look at http://homepage.ntlworld.com/fast.electrics/articles.htm and scroll down to Transmitter modification - adjustable servo movement.

Barrie

[firstime67]

Hi Barrie

Had a look at the site. Unfortunately my transmitter potentiometer is so wired that the mod suggested would not solve my problem. I will have to look further. Will see if Futaba are helpfull in the matter, with the transmitter and Hitec for the servo.

Your site certainly has some interesting stuff in it, thanks.

Firstime67

[barriew]

It was a Futaba 2 channel 40Mhz that I modified. I thought all sets with more than 2 channels had adjustable throw built in. That's why I bought my two Hitec txs.

Good luck with the problem!

Barrie 

[ukengineman]

I have done this mod on a 2 channel Futaba Tx and it works fine. I can now set just the right movement on a Hitec Hs785 in an IOM yacht.
Alan

[firstime67]

Hi all
 I thank you for help in the matter of controlling my Hitec HS785HB to rotate for two revolutions.
Successfully modified my Futaba T4YF 40MHz transmitter, using the information gained from this forum, and web site http://homepage.ntlworld.com/fast.electrics/articles.htm .

Best regards.

firstime67