Hi:

I came into a beocord 9000 tape deck with a non-functioning motor. When you hit play, the relay will engage the head assembly into the cassette but the motor will not turn. After a few seconds the mechanism releases.

I checked for bad belts but they are OK.

With play depressed I manually try to rotate the motor shaft and can feel flux in the motor, however it will not rotate very freely on its own, sometimes very slowly and then quite.

I tried to manually spin the motor while it was powered and this caused the 250 mA fuse to blow.

If someone has experience with this problem could you give me a few ideas on where I might start to look?  The 2.2 uF cap across the inductors on PCB 5 is not shorted. I'm thinking perhaps it is the transistor that is piggybacked onto the motor. It isn't in the schematic but seems part of the motor assembly.

Thanks,

Derek

Usually the motor brushes are defect, causing a short. It makes no sense to repair this motor because the collector is also burnt by the heat.

 But you can check the motor itself, remove the small electronic board in the motor and test it with a seperate power supply. Then you see wether it's the motor or the electronic.

Hi:

Thank you for your reply. I hope the motors are not expensive to replace!

Regarding the theory of operation for the motor:

 
It has 3 wires on it. How does this work? I assume you have a +/- and the third? Is that some feedback signal? Does this motor operate on a servo system?

Thanks,

Derek

 

Yes, it's a tacho system for constant speed.

 But the motor itself has just 2 wires and is quite normal like any other e-motor.