I have an MC2100SD1-12 controller. I built a PWM using an NE556. I can vary the PW between 15 msec and 40 msec at a PRF of 50 msec. I am using this to drive a wood lathe. I placed a magnet on the drive pulley and connected the RPM sensor to the two terminal block marked HD7. When I first turn it ON it will run for about one minute and maintain speed. I have also used the sensor from the tilt motor to drive a tachometer so I can see the actual speed. After this first minute the motor will start to slow down and finally stop, The LED on the board is steady. Once in a while the LED will flash and the motor will try and turn. Measuring the voltage across the motor terminals confirms 0 volts when it is stopped.
I also measured the output of the line bridge and it was 108 volts. This seems low, I did measure the diodes in the bridge with a DVM in the diode mode but bridges can be misleading with this method.
Looking at the reverse engineered schematic, the zener D8 shows a 1N474. Mine is a 1N4744 and it measures 15 volts which is per spec.
One thing that is puzzling, the DC motor voltage referenced to bridge common is in the area of 150 volts on both sides of the motor when stopped.
I do have an HP1740 scope but I am reluctant to connect the ground of the scope to the common on the bridge output since this circuit is floating.+
Any ideas on the next step in T/S would be helpful.
Best regards,
wings515
I also measured the output of the line bridge and it was 108 volts. This seems low, I did measure the diodes in the bridge with a DVM in the diode mode but bridges can be misleading with this method.
Looking at the reverse engineered schematic, the zener D8 shows a 1N474. Mine is a 1N4744 and it measures 15 volts which is per spec.
One thing that is puzzling, the DC motor voltage referenced to bridge common is in the area of 150 volts on both sides of the motor when stopped.
I do have an HP1740 scope but I am reluctant to connect the ground of the scope to the common on the bridge output since this circuit is floating.+
Any ideas on the next step in T/S would be helpful.
Best regards,
wings515