[DG] [DG11] Drivestop issue

[billgcroton]

Hello,

I have a circa 1986 autopilot with certain upgrades having been made in the interim.

Type 300 Course Computer -- original
Rudder sensor-original and works fine
Fluxgate compass replaced about 5 years ago.
ST6000+ (upgraded about 10 yrs ago).
Type II linear drive

---Clutch operates fine when engaging auto, but pilot does not steer (pressing +10 and -10 results in DRIVESTOP error.

I am getting 12V at the Power input to the 300
I am getting no response when I connect the MOTOR wires to 12V (both directions).
I am getting only around +/- 7.5 volts at the MOTOR terminals on the 300 when pressing +10 and -10.

So the drive motor seems to need service, but the 300 Motor output seems to be under volt.

What other troubleshooting tests should I do before deciding what to do next?

[Derek - Raymarine - Moderator]

Hi Billgcroton

Thankyou for your enquiry.

There are two possibilities, the output of the T300 is defective or the motor/ motor brushes in the drive are worn out.

Note that when the motor is open circuit, the T300 Automatically drops the voltage output for a short time before dropping to 0v completely.

Test the motor as follows

Disconnect the two motor leads from the T300, note their polarity, engage AUTO to energise the clutch, then temporarily 'dab' the motor wires onto the main power connections to the T300 - note that there will be a small spark and be carefull not to short out the wires. once the motor wires are connected direct to the normal supply voltage and with the clutch engaged, the drive should operate. if the drive still does not operate, then check the motor wires for damage or loose connections and if this is all OK, then the issue is within the drive motor itself and if the brushes are worn away, the motor bearings will also be worn, so get the electric motor replaced.

regards

Derek