I happened to find a motor from my salvaged parts in the store.. Its not an ordinary one. It is marked DC 6v and MMI-6S6LK.It has 4 terminals and I guess i found it from a tape recorder abt 8 yrs ago.. It looks new and has one + and - marked ouside with a back emf protection zenner across.. then there are 2 other terminals one which is connected to the case and has a point for connection. The other point has no markings. I managed to dissemble it and got a ckt brd with the print side open and the part side inside a cap which I can't remove due to the punched brushes.. It has a pot onboard, an electrolytic cap, and a transistor like thing with 4 legs.. i couldn't see what it was,, just a small peep.. what is this motor?? Is it a servo ? I don't think its a stepper. It runs at low speed with 6v supply to the 2 connections apart from the + & - ... Can I run it with PWM? And which terminals to connect?

 

I happened to find a motor from my salvaged parts in the store.. Its not an ordinary one. It is marked DC 6v and MMI-6S6LK.It has 4 terminals and I guess i found it from a tape recorder abt 8 yrs ago.. It looks new and has one + and - marked ouside with a back emf protection zenner across.. then there are 2 other terminals one which is connected to the case and has a point for connection. The other point has no markings. I managed to dissemble it and got a ckt brd with the print side open and the part side inside a cap which I can't remove due to the punched brushes.. It has a pot onboard, an electrolytic cap, and a transistor like thing with 4 legs.. i couldn't see what it was,, just a small peep.. what is this motor?? Is it a servo ? I don't think its a stepper. It runs at low speed with 6v supply to the 2 connections apart from the + & - ... Can I run it with PWM? And which terminals to connect?

The extra terminals and components are most likely a speed (RPM) pickup.
You can most likely just ignore the extra components and just use it as a DC motor and yes you can drive it with a PWM driver.

Lefty

 

So which all terminals should I use to use it as a servo with PWM?
Positive 6v, -ve, case and one other connectors are available.

Also Does a servo motor have braking feature?? Like control it not rotate.. Ordinary dc motors can be done so by using an H bridge.