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Old 02-28-2005, 07:21 PM   #1
rc al
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servo reverseing

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can you reverse the polarity on a hitec servo to make it work backwards. I am aware there are reverce servos on the market. just wondering if this is the dif. or not???thanks
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Old 02-28-2005, 07:38 PM   #2
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I've done it with Futaba's servos with great success. When you get the servo taken apart just switch the 2 outside wires going to the pot, remove the motor screws,unsolder it from the board and turn it 180deg. Make sure to have strong solder joints so nothing shakes loose during flight. I assume you're modifying one for an aileron. I did.
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Old 02-28-2005, 08:10 PM   #3
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So Chuck... you have to do both? Pot and motor?.... I'm curious too because I have just used a reversed servo (hobby lobby cirrus) in the past... The problem with them is they have slightly more or less travel (using the same length servo arm) than the other servo i'm using... I'm using them both for flaps so I can't change the travel in the radio....
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Old 02-28-2005, 08:28 PM   #4
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Chuck is correct, you must do both, the pot and the motor.
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Old 02-28-2005, 10:09 PM   #5
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Came across this (just posting, not recommending):

How to Reverse Servos By Soldering

Sometimes there are unavoidable situations where you need to reverse a servo. Unfortunately although in the majority of cases you simply use the Servo reverse facility found on all modern Transmitters, there will always be the situation where you will need a servo to be physically reversed such as twin rudders or elevators where 2 Servos are ued and they are connected to a Y lead. In such a case reversing a servo at the TX would reverse the other one also, so a mechanical solution is called for.
In this short tutorial I will reverse a couple of old servos to demonstrate the technique and hopefully encourage you to have a go yourself. I am using a Futaba 148 and a Hitec 422 for this, as I belive they are the most common Servos in use today.

Tools Required

Fine Soldering Iron 15 to 25Watts
Side cutters
Philip Head Screwdriver
Connecting Wire

Time For Surgery

Remove the four screws holding the servo case together, remove the bottom of the caseand the top case with the gear set. Looking at the bottom of the Servo you will see that the Hitec uses wires to connect to the motor and the Futaba motor solders directly to the PCB.
Lift the PCB (circuit board) of the Hitec Servo up and inside you will see the Pot. This Pot forms a feedback loop with the Servo mechanics and tells the servo where it is in relation to your stick position.
Look closely and you will see three wires soldered to the Pot, It is the outer two wires that need to swapped around and you can either do this on the Pot itself or at the PCB. If you are not proficient in fine Electronics soldering then I recommend changing them over at the Pot.
That's the hardest part done and all we need to do now is to reverse the wires that are soldered to the motor and reassemble the servo.
When done connect it up to your Reciever and now if you compare it to a normal servo it will run in the oposite direction.
In the Futabas case things are slightly more complicated because although we are doing exactly the same thing, Servo construction makes it mechanicaly more difficult.
As stated earlier the Futaba PCB covers the whole bottom of the case and has the motor soldered directly to it, so to acess the Pot we will need to remove the Motor as well. This is not as hard as it sounds and all you need to do is remove the 2 Motor retaining screws on the top of the case and give the Pot spindle a gentle press (the Pot is reained by a simple snap in fitting). The PCB complete with Motor and Pot will pop out of the case.
Unsolder the Motor from the PCB then simply turn it around and resolder, making sure that it is sat right down on the board.
Instead of being on flexible connecting wires the pot is on rigid wire and you will need to cut the wires and replace them with flexible wire, crossing the outer 2 over in the process. Use flexible connecting wire about 1.5" long for this.
Now pop the Pot back into the case making sure that it is correctly seated and then slide the Motor/PCB assembly into position. Replace the 2 Motor screws and ressemble the servo.
All of this takes much longer to explain than to do. Just take your time and it's easier than you will think possible.
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