My trim motor operates OK when hooked up to a battery attached directly to the motor, however when operated from the cockpit it moves to the full deflection but will not go back the other way. There is power available in both directions but only 9 volts. Can anybody shed some light on this problem.
Van's Air Force
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Trim Operation
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- Start date
By saying that you have power available in both directions do you mean that you have +ve on one white wire and -ve on the other and this reverses when you operate the trim switch the other way 9 volts should be enough to drive the servo does it stay at 9 volts when the switch is pushed each way
Trim PWM
Check out these links:
http://www.vansairforce.com/community/showthread.php?t=48514
http://www.vansairforce.com/community/showthread.php?t=48023
The control board sends a Pulse Width Modulated (PWM) signal to the trim motor. Your meter averages this out and indicates about 9 volts DC, but it is actually pulsing 12vdc. Have a young helper listen to the motor as you operate the cockpit switch. There should be a high pitched whine. If there is no noise, suspect the switch. If there is noise but the motor does not move, try adjusting the trim pot on the back of the control board, CCW I think.
Also check for mechanical binding.
Joe
Check out these links:
http://www.vansairforce.com/community/showthread.php?t=48514
http://www.vansairforce.com/community/showthread.php?t=48023
The control board sends a Pulse Width Modulated (PWM) signal to the trim motor. Your meter averages this out and indicates about 9 volts DC, but it is actually pulsing 12vdc. Have a young helper listen to the motor as you operate the cockpit switch. There should be a high pitched whine. If there is no noise, suspect the switch. If there is noise but the motor does not move, try adjusting the trim pot on the back of the control board, CCW I think.
Also check for mechanical binding.
Joe
aussi
Further to this problem. In it's static state the wieght of the trim foil has to be overcome when the motor and square shaft is pulling in (forward) so for testing the system the trim foil should be disconected. After disconecting, the motor was still hit and miss in it's operation so next I removed the top cover from the motor/gearbox and the unit worked OK about 75% of the time. The problem with my unit appeared to be too much friction especially in the square piston. With great difficulty I eased some material from around the hole where the piston slides and with the lid back on it now works as designed. I understand that it is built with very fine clearances to avoid water penetration however if these almost no clearances prevent reliable operation what is the point.
Further to this problem. In it's static state the wieght of the trim foil has to be overcome when the motor and square shaft is pulling in (forward) so for testing the system the trim foil should be disconected. After disconecting, the motor was still hit and miss in it's operation so next I removed the top cover from the motor/gearbox and the unit worked OK about 75% of the time. The problem with my unit appeared to be too much friction especially in the square piston. With great difficulty I eased some material from around the hole where the piston slides and with the lid back on it now works as designed. I understand that it is built with very fine clearances to avoid water penetration however if these almost no clearances prevent reliable operation what is the point.
