MC-60 PWM Controller Modifications

Chucketn

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I am cross posting this question to several forums.
I have 2 Proform MC-60 treadmill motor controllers, one of which is currently running my X2 mill with its (from the treadmill) 2hp motor.
I have it set up with the original heavy choke, and the original line switch/circuit breaker from the treadmill, and a 5k pot from radio shack for speed control. It works, but still has the soft start feature, and the pot must be turned up about 50% to start the motor. I found some instructions for modifying this controller to remove the soft start, and one that supposedly will allow setting speed and being able to turn the motor on and off at the last speed setting. Only problem, the controller schematic provided with these instructions, doesn’t seem to match the Proform MC-60 I have.
Has anyone modified this controller to remove the soft start? Will a 10k pot make the speed transition smoother?
I have a data sheet on the controller from Surplus Center which pictures the board and shows the connections, but not a proper schematic.

Chuck in E. TN
 
I am a member at All About Circuits and it is a great source of electronic info. If you need assistance registering please let me know and I will be glad to assist you in any way possible. The MC-60 is very very common and has a long list of mods so if you get lost let me know. AAC is the "Hobby Machinist" of the electronic world. A very colegial and well run forum that has a great depth of knowledge.
Bob
 
I have joined the "All About Circuits" forum and have downloaded those files. Thanks for the link.
I also have found an old post from rec.crafts.metalworking that listed a couple of mods to the MC-60 controller to remove or lessen the soft start. One was clipping a resistor RPS3, and the other was removing Q7 and C7. I did all 3, but the motor became jerky in operation and made a loud humming noise.
I reinstalled Q7 and C7, but not RPS3, and operation was restored to that previous, except the motor starts with less turns from 0 position.
I get spindle speeds from around 50-60 rpm to 2700 rpm as it is now and can shut off the motor via removing the AC anywhere abouve about 300 rpm spindle speed and the motor will return to same speed when I turn it off and back on. Any lower than that I have to turn the speed pot up to get the motor started and then adjust speed.
Any other info or ideas? One mod from rec.crafts.metalworking lists removing transistor T3 to eliminate the soft start, but all transistors on both boards are labled Q#.
The two MC-60's I have are different revisions (G, and J)and some of the components are in different locations, but all connections to the board and the IC's and transistors are the same.

Chuck in E. TN
 
I just came across an old treadmill 2 hp motor and MC 60 controller and just started looking for info on why it won't run the motor. So far the only thing I have noticed is the SCR trigger led isn't doing anything nor is the CUR LIM led lit. Other two LEDs are on, done all continuity checks on motor, transformer and wiring so I am down to the board.
The old machine sat outside for awhile because it was headed for the dump but worked prior to being stuck out on the patio.
I am pretty good with electricity and have a good understanding of motors both AC and DC, but a rookie at circuit boards.
Most of them I have fixed has been by just replacing visually burnt or damaged components.
My goal is to try this motor on my benchtop mill, I am sick of changing speeds by belt changes. Mill is a 2 hp Rong Fu by Shop Fox.
Besides I am a die hard tinkerer.
Thanks
 
I just came across an old treadmill 2 hp motor and MC 60 controller and just started looking for info on why it won't run the motor. So far the only thing I have noticed is the SCR trigger led isn't doing anything nor is the CUR LIM led lit. Other two LEDs are on, done all continuity checks on motor, transformer and wiring so I am down to the board.

Thanks

How have you tested the board? You will need a 5K ohm linear pot connected to the board in place of the console control for testing/operation. This controller, as most if not all treadmill controllers, has a 'soft start' feature. The speed control pot must be set to zero and increased again to start the motor to prevent throwing the user off the treadmill. I tried finding a way to defeat that feature on the MC-60, but was not sucesasful. Instead, I added a Hall effect speed pickup/input to my DRO and use that to reset the speed when starting. Hope this helps.
I've gotten used to the soft start and it's second nature now.

Chuck
 
How have you tested the board? You will need a 5K ohm linear pot connected to the board in place of the console control for testing/operation. This controller, as most if not all treadmill controllers, has a 'soft start' feature. The speed control pot must be set to zero and increased again to start the motor to prevent throwing the user off the treadmill. I tried finding a way to defeat that feature on the MC-60, but was not sucesasful. Instead, I added a Hall effect speed pickup/input to my DRO and use that to reset the speed when starting. Hope this helps.
I've gotten used to the soft start and it's second nature now.

Chuck

Hi Chuck,
I am testing these with the original wiring harness minus speed sensor, which does not seem to connect to anything but the digital readout board, though I have wondered if somehow beyond what I can see the speed pickup signal gets back to the MC60.
Since my last post I have bought two more 50 dollar treadmills and ironically they were both Sears Pro-forms and have the same 2 hp motors and MC60 controllers as the first one I started with, which came off a Weslo. The MC60 controllers are different part #s but all revision J and have the same resistors snipped. So now that I know I can make them work outside of the treadmill, I am back to trouble shooting the first MC60 to see if I can repair it and have a backup or extra controller to experiment with. My original goal was to get one of these for my drill press and the other for my Rong Fu 31 mill.

I am very curious as to how you use the hall effect sensor connected to the DRO to reset the MC60? Isn't hall effect the one that creates a small electrical pulse, and how does this get back to the MC60? Does it connect to the Pot and show it a on-off-on signal to reset it without actually moving the Pot.

And do you think I will have any problem with just using a DPDT 15 amp toggle switch to reverse the motor? It should handle the load OK?

The other thing I am working on is to make a dual drive system on the mill where I can quick change from the original 2hp AC 220 volt motor over to the DC motor quickly, by building an intermediate shaft that has both motors connected to it by belt and shift cog between the two driven pulleys to drive the shaft which drives the original step pulley system on the mill. This would also enable me to have two extremely different speed ranges by using different input drive ratios to new intermediate shaft. Something like 10 to 1500 rpm and the other 1500 to 20000, leaving the original step pulley system intact. Though I do not know how stable the Rong Fu spindle would be at higher speeds? If I really get crazy, I have some small self contained hydrostatic transmissions from old equipment I use in my business I could put in the drive system.
I am much better at mechanical than I am at electronics so that is why the dead MC60 has become the challenge of the day, even though I know it is not worth the time to repair, it is more in "Can I Fix It".

Thanks for the Input.

Goodbye for now
 
I don't reset the controller with the hall effect. I use the hall efect and a magnet epoxied to the spindle as a rpm input to my Shumatec 550 DRO. I still have to turn the speed down and back up to restart the motor.
The DPDT sw sounds o.k. Just check it for getting hot when running. Does the switch have a center off?

Got to run to Knoxville for a while. Be back this afternoon.
Chuck
 
Cut the center wire on the pot ( wiper) and wire in your motor start and atop switch, now you start at the speed you left it at.
 
Cut the center wire on the pot ( wiper) and wire in your motor start and atop switch, now you start at the speed you left it at.

Can you explain where to put the start and stop switch and what kind of switches you used?

Chuck
 
I've eliminated the soft-start feature on a handful of MC-60 boards, just by clipping the resistor labeled RPS3. No other mods were required in my situation.

You can create a momentary Jog feature by defeating your potentiometer similar to this drawing:
Please ignore the motor wiring and other connections. Just consider the POT and JOG components.
jog.gif


Matt

jog.gif
 
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