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Author Topic: Servo rotating only in one direction ??  (Read 2097 times)

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Offline ibotTopic starter

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Servo rotating only in one direction ??
« on: April 25, 2010, 02:21:37 PM »
Hi,

I recently bought a Hitech 485 servo. While modifying it as a continuous rotation servo, accidentally the top part of the pot head got cut in the process. Now, my servo is only rotating in one direction regardless of the signal  :(

Not sure what happened .. wondering if anybody can help me how can I make such servo rotate in both directions ? Please let me know if you need more information .. probably, I will get some photos meanwhile.

Thanks!!

Offline Xyver

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Re: Servo rotating only in one direction ??
« Reply #1 on: April 25, 2010, 02:32:50 PM »
I had this problem too, and i found out that i glued the pot in the wrong spot.  It was all the way over to one side, not right in the middle.  It was a pain to un-glue it, but it works now.  You could check that, and hopefully that will be the problem :D

Offline Imignant

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Re: Servo rotating only in one direction ??
« Reply #2 on: April 25, 2010, 03:18:40 PM »
not sure what you did to the pot, but you can always just remove it or replace it with one from a junk servo. here is a link on how to remove it.
http://www.laureanno.com/RC/servo-rotate.htm
remember the resistor ends attach to the two outside wires of the pot, so make a note of the colors before you remove the pot.
hope this helps

Offline Soeren

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Re: Servo rotating only in one direction ??
« Reply #3 on: April 25, 2010, 05:39:32 PM »
Hi,

Just to add...
Don't be too hung up on the resistor value of 2k2, anything higher you may have ready, up to eg. 10k, will work as long as they're equal.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ibotTopic starter

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Re: Servo rotating only in one direction ??
« Reply #4 on: April 25, 2010, 05:45:42 PM »
Thanks for the replies,

I will try replacing it .. Greatly appreciate your help !!

Thanks!

Offline ibotTopic starter

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Re: Servo rotating only in one direction ??
« Reply #5 on: April 26, 2010, 10:49:34 PM »
Actually, I got another servo which had similar issue while modifying.

But, this servo rotates forward and backward when we send 2 and 1 .. but for 1.5 .. it is still rotating forward though..

wondering, if somebody can help me to get it stop rotating at 1.5 signal ?

Greatly appreciate your help !! Thanks !

Offline SmAsH

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Re: Servo rotating only in one direction ??
« Reply #6 on: April 27, 2010, 12:22:41 AM »
Erm, did you open up the servo, send it 1.5ms pulses and turn the pot until it stops turning?
Howdy

Offline ibotTopic starter

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Re: Servo not stopping at 1.5 ms pulse [changed the subject]
« Reply #7 on: April 27, 2010, 03:41:03 PM »
actually, this was my first servo I tried modifying. I opened the servo and sent 1.5 ms pulses. But, the pot head got cut in the process while rotating it [same thing happened for two of my servos .. I found I am using a wrong tool to rotate :( ].

So, the servo end up rotating either forward or backward continuously when I send 1ms or 2 ms pulses. But, when I send a 1.5 ms pulse, it was still end up rotating forward. I guess, the servo got corrupted. So, trying to see if this ever happened to anybody and does anybody fixed it some how?

Wondering, what exactly happening in the back when we rotate the pot head at 1.5 ms pulse? interested to learn more on this. Also, wondering if replacing any part might bring the servo functionality back to the factory settings.

Greatly appreciate your help !! Thanks !!

Offline Soeren

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Re: Servo not stopping at 1.5 ms pulse [changed the subject]
« Reply #8 on: April 27, 2010, 03:54:13 PM »
Hi,

Strange, I posted another note earlier, but now it's vanished.

[...] But, when I send a 1.5 ms pulse, it was still end up rotating forward. I guess, the servo got corrupted. So, trying to see if this ever happened to anybody and does anybody fixed it some how?
Just mount either two equal resistors of 2..10k or, if that won't hold it still at 1.5 ms, mount a small trimming potentiometer between eg. 5k and 20k, send a pulse of 1.5 ms and adjust until it stops (near center setting).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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