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This is the DC motor of yamaha mt1x 4 track tape recorder. The motor is not working and i would like to know maybe if i can fix it. This motor turned for a while and then it totally stopped.

I opened the motor coils look fine to me. coils of the motor

These are the brushes and the circuit. In the picture there are also voltages i measured when the motor was connected to the tape recorder.

motor circuit.

This is the motor when it is in the device. motor in device

And tgis is its cap and part number. enter image description here

The motor disconnected from the device when i power it with 9v it draws 20 mA which is too low i guess. I am very unexperienced with motors. Would you point me to the right direction for debugging this motor? Unfortunately i couldn’t find the datasheet. also why do i measure the supply voltage on the middle two pins?

Thank you.

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  • \$\begingroup\$ Before trying to fix it I'd look at why it has failed in the first place. The motor is marked "DC9V". The capacitor on the control board is rated 16V. It seems 17.4V is way too high for this motor, the chip on board could have been damaged irreparably. But check the cap, or simply replace it. Might help. And don't connect it back until you fix voltages. And check what you getting on speed control wire. \$\endgroup\$ – Maple Jul 13 '18 at 16:19
  • \$\begingroup\$ Speed control wire was reasonable between 6 and 8 volts. I would appreceate if you give info about what voltages to to expect at the middle two pins. If i know that i can trace and find a problem in the tape recorder maybe. \$\endgroup\$ – Ali Somay Jul 13 '18 at 16:24
  • \$\begingroup\$ I have no idea what that motor is. As I said above, it has markings "DC9V", so my guess would be 9V. The capacitor is usually selected with wide safety margin, so if it is rated for 16V it also confirms 9V guess. Or at most 12V. Check the PCBs and other parts for markings on them. You can often find voltages next to connectors or wire soldering points. \$\endgroup\$ – Maple Jul 13 '18 at 16:39

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