The Shop > Electronics & IC Programing
MC-60 Motor Control
John Rudd:
What seems to be the problem?
Chuck in E. TN:
The resistor mentioned seems to be the big 5W power resistor, right? I can't find a designation of R42 on my two controllers. Maybe a picture would help. My controllers are in my freezing cold garage, both mounted in difficult to see places. I scanned them with a flashlight but did not see the label for R42.
Chuck
John Rudd:
According to john swifts link, the big resistor is R9.....5k rated at 5W.....if it's open then the speedo won't run.....
Chuck in E. TN:
Here is a link to a thread on this controller.
http://forum.allaboutcircuits.com/showthread.php?t=77083
You will have to join the forum to see the circuit diagrams, but I think you will find it worthwhile. It's an old thread, but discusses the had drawn schematic presented earlier in this thread, and has some more info on the MC-60 controller.
Chuck
unc1esteve:
I found this site but did not want to join.
Attached is a picture of my board. The dirty finger
is pointing to the position of r-42. It is the first resistor
on the bottom right corner. The mosfits are at the opposite end.
Next to the r-42 position it says spd cntl. Under the r-42 it says rps1.
This resistor is missing on my board. I found the suggestions mentioned,
including yours, Chuck,
and tried several replacement resistors but they do not seem to be
the correct value including 5.4k.
The board will function without this resistor however it lacks what I call
torque. The motor under load will start very slowly, run for a few minutes
and then stop with the motor trying to continue to run.
Replacing the missing resistor, the motor starts very nicely but again will
stop after a few minutes still trying to continue to run.
I have adjusted the speed control. I found one resistor, r38, had a severed
lead wire. I only found this out after touching each component with an insulated
screwdriver.
With this repaired the control is almost completely operational. It just lacks the
correct starting torque and the running torque as it slows down under a load.
I found the treadmill in the rubbish dump. I stripped it down to use as power
for a small green sand mixer. I used the incline motor to position the mixer
to raise and lower for emptying.
I am now adding a mechanical speed reduction to slow down the speed and
add more torque.
Since the control will work without r-42 I thought that the value of r-42
would be very high? All I need is to find the correct value to keep the mixer running.
I will again try 5.4k when I complete the reduction.
Thank you.
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