Teac X300, dead capstan motor

[Macdude]

I just acquired a Teac X300. Everything works except the capstan motor will not turn. The belt is shot but the motor spins freely, any ideas on where to start? Does anyone have a copy of the schematic?

 

[KentTeffeteller]

Hi,

You need a copy of the full service manual. You could likely find one online somewhere.

 

[Macdude]

One is on the way. I was just hoping maybe someone could show some insight as to what to check first.. Normally I get lucky and it's just a belt.

 

[Ozric]

When you lift the tension arms, does the motor spin ?

 

[Macdude]

Ok, so when the shut-off switch is engaged (UP, tape threaded) I get +30VDC on the + side of the motor and +1.2VDC on the - side.

When the switch is disengaged (DOWN, tape not threaded) I get +30VDC on the + side and +23.2VDC on the - side.

I assume the +23.2VDC just acts to cancel out any current flow and stop the motor? I can't measure any voltage on the FG leads, but I don't think there should be any present there. From what I can tell, the motor is getting juice, but it doesn't turn, does my logic sound accurate?

 

[jblmar]

Difficult to tell without the schematic.
Are you measuring those voltages with reference to ground?

Ron

 

[Macdude]

The reference is to ground, that is to say the black lead of the meter is grounded to the chassis. Obviously I'm not the brightest when it comes to repairing electronics... mechanical I'm fine with.

 

[KentTeffeteller]

Hi again,

Teac X-300 decks are prone to capstan motor issues and/or motor switch issues. These motors were weaker than the ones found in A series machines. I would check both items. This also goes for the Realistic TR series machine which was the X-3 and X-300's father. Yes, this unit was originally Teac made for Radio Shack and they were such huge sellers that Teac was forced to sell this as a Teac though not built to Teac standards. :tears: Replacements are also scarce if you need one.

 

[Macdude]

Crap. :sigh: Well we'll see, maybe I'll get lucky and it won't be a dead motor.

 

[jblmar]

Look at the associated parts first before concluding that the motors bad. The DC Servo motor decks are known for component failure external to the motor.

If you have an oscilloscope, you can check the waveforms to the motor. You'll need the SM for that.

Ron