Servicing Guidelines for models with Heading Dial

Older model CPT's can often be serviced and repaired, but whether it is worthwhile or not depends on how hard it has been used or abused over the years.

On older CPT models from 2004 and earlier: It is usually not worthwhile to perform major repairs such as rebuilding the optical compass or replacing the circuit boards. Please contact us before shipping your autopilot in.

A brief self-check and diagnostics

Here is a brief run-down on advice and what we recommend, based on our experience:

Normal servicing will remedy the typical parts that wear and includes replacing relays, rudder and deadband controls and all seals and gaskets.

Major repairs are usually not cost effective, such as replacing the motor and rebuilding the optical compass, replacing circuit boards. The cost can approach the cost of a new replacement pilot, yet still have liabilities because of its age and worn/stressed parts.

Self Check:

1. Motor & Torque: With the unit plugged-in to a 12v source, engage the clutch (push it inward), turn the rudder-control to 10 and deadband to a low setting, with the sensor 20-degrees off-heading. While holding the drive box, grip the disk on the clutch while it turns: the motor should not slow appreciably or stop. If you can slow the motor RPM more than 50% with your hand the motor is worn and has low torque. With wear, the motor gradually increases current draw, limiting relay life and over time cause circuit damage. When replacing an older motor, a new clutch and stainless drive plate must also be installed.
2. Housing Condition: Take a close look at the drive and sensor boxes. Are the aluminum edges bent or scraped from someone prying the unit open, or does it appear someone has opened and attempted repairs or changes? If repairs or modifications have been attempted it will make troubleshooting and repair more difficult and we may be unable to repair the unit at all.

3. Clutch gear: Take a close look at the clutch on the drive box. When disengaged (pulled outward ¼") does it wobble on the driveplate shaft or does it have a fairly straight and snug fit? Look carefully at the shear-pin tips protruding from the clutch-gear, is there evidence that the shear-pins have been improvised by filing off the threads of a screw? With the clutch engaged (pushed in so it doesn’t freely turn), when you rotate the clutch back and forth with the shear-pins engaged in the stainless disk & drive-plate, does the drive-plate or stainless disk rotate with some play?

   If the gear is wobbly or has a loose fit on the shaft, the pilot has seen extensive use; at least use without maintenance and lubrication. Home-made shear-pins will not shear as needed, and may have subjected the motor to excessive loads and damaging stall currents. This is an indication that the pilot has seen some hard use and may not be worth repairing. If the stainless drive-plate (the shaft & disk that the clutch spins on) has some rotational play approaching 1/8" when you rotate the clutch, the motor has been subjected to heavy loads and may have broken or worn internal parts on the armature shaft. It cannot be reliably repaired, current draw from wear will eventually cause it to fail and cause other circuit damage.

4. Water Damage: If the pilot has suffered from water intrusion, actual water in the sensor or drive-box the unit cannot usually be repaired.
5. Basic Circuit function test:

   Connect the power cable to a 10-amp fuse and connect to a 12v battery. (Reversing polarity will reverse the motor direction, but will damage an older chain drive model.)

   Turn the unit on, set Rudder to 5 and Deadband low. Slowly turn the sensor dial in a clockwise direction in a gradual 360-degree rotation while watching the movement of the motor and clutch.

   If the motor makes both port and starboard corrections, all the basic circuits are functioning. If the motor only turns one direction, or only briefly turns when powered on, there is a problem in the drive circuits or sensor signal. Often turning only one direction is the result of a worn relay and you can hear a faint “clicking” sound from the faulty relay when the motor should be turning. If the motor does not operate at all, it could be problems with relays, the drive board power circuit, or the motor. (Opening the unit and applying 12v to the motor will backfeed and immediately damage the autopilot circuits.)

   If the motor continually runs in one direction without stopping it may be due to worn rudder/deadband controls or the signal from the optical compass.

Service