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Help with modifying a servo for continuous rotation? Answered

I want to build a robot with arduino and for the motors I was going to use some servos that I could modify for continuous rotation.  So, I picked up 2 cheap ones at radioshack.  I opened them up and I can get to the gears by removing the top part and I can get to the back of the circuit board by taking off the bottom.  But the circuit board is soldered in so I can't take it out to get to the potentiometer. I tried desoldering the connections to the motor but there seems to be more joints to desolder before I can take out the circuit board completely. And I don't want to desolder every joint and then have to solder them again when I need to put them back together.  So has anyone modified these radioshack servos and can tell me how to get tho the potentiometer? Or can anyone tell me if there is a way to modify them without getting to the potentiometer?
Thanks.

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AndyGadget

4 years ago

If you've got the right type of servo, I've found this method easier then the 'cut pot wires and add resistors' method on small servos.

You've got the gearing side apart, so look at how the final gear rotates the potentiometer shaft. Some types have a flat at the top of the pot shaft which locates in a 'D' shape at the top the gear. By running a very small drill through this part of the gear you can round off the 'D' so the final gear rotates without turning the pot shaft.

Before you reassemble the gear-train, you'd then either set the pot roughly to mid-point (turning the shaft with a small pair of pliers) and set the software mid-point to suit, or connect to your circuit with the servo output set to your desired mid-point and turn the pot shaft until the motor is stationary.

Ideally you'd drop a bit of epoxy on the pot track so there's no way it can move, but it sounds like that's not an option in your case, but as long as the pot shaft isn't contacting the final gear, you should be OK.

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-max-

4 years ago

If you desolder the control board from the motor and cut the connections to the pot, then toss it aside, and build a small DC motor controller, you should be good. These mods are only if you need a motor with a gearbox attached to it. You cannot accuracly control the position of the motor.

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texpertKiteman

Answer 4 years ago

I know what I need to do, I'm saying I'm having trouble getting to the component I need to get to.

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Kitemantexpert

Answer 4 years ago

Oh, I get you, but maybe one of those contains the answer.

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texpertKiteman

Answer 4 years ago

I've been looking through them, the only one that has the same problem I did, only had to desolder the motor connections. That's why I'm at a stand still for now