hi there -

i am attempting to repurpose an 8-track tape machine for variable speed. in other machines, i sever the main connection to a motor and install a voltage regulator. in this case, the motor in the machine is a matushita 164n034, and has two pairs of wire routed into it.

can anyone help me make sense of what these extra wires might be for and how i might control the speed of the motor?

 

It may be a stepper motor or it may be a simple motor with a speed sensor.
Some resistance readings between the wires should help.

 

I should add that one of the four wires is definitely connected to ground - which makes me think it's not a bipolar stepper, since there is usually a fifth connection for that, right?

What might I be looking for in my resistance readings?

 

What might I be looking for in my resistance readings?

That would be a bit of a wild guess, not having seen the thing.
Let an ohmeter be the best judge.

 

Alright - having looked closer, I noticed an extra wire. Let me include a photograph and share my readings, maybe that will help with a diagnosis.

There are two pairs of wire. A red/white pair (passed through grey insulation) that seems to be hinged to the Fast Forward Switch on the chassis (which has an additional grounding wire that I missed, initially)...and a larger red/blue pairing.

The grounding wire and the blue wire are both connected and grounded.

There is a 22 ohm resistance between the red and white wires and 200 ohm resistance between the red and blue wires.

Does this indicate anything to anyone? I know nothing about this stuff.

 

I should add that this is a Matushita 164N034 motor... and it is spec'd at 13.2v DC. I don't know if phase-based motors are all AC based or not.

 

Does the motor turn freely or does it 'cog' when spun?
Fractional voltages, 13.2v for e.g. usually appear in stepper motors.
If it was a bipolar motor there would be identical readings between each winding.
Max.

 

I should add that this is a Matushita 164N034 motor... and it is spec'd at 13.2v DC. I don't know if phase-based motors are all AC based or not.

It's described as a turntable motor and clockwise or anticlockwise by reversing the wires so I expect it is a PM DC motor with speed sensor.

 

It's described as a turntable motor and clockwise or anticlockwise by reversing the wires so I expect it is a PM DC motor with speed sensor.

Probably confirmed by spinning the shaft and see if DC generated or a pulsed output (stepper).
Max.