MC-60 Motor Control

[unc1esteve]

Does anyone have an icon mc-60 motor control?
I am trying to repair one but resistor #42 is missing.
Does anyone know the value of r-42 or have a schematic?
Thanks.

[Chuck in E. TN]

unc1esteve,
I have 2 models of MC-60 controllers in operation. I will check them out in a few min. Need another cup of coffee while the pups play.
Don't think I have a schematic though, but I'll look.
Chuck

[unc1esteve]

Thanks much.

[John Swift]

going by this link to a circuit :- https://docs.google.com/file/d/0B7EYRdZSNmy7Z1R6TklROXlBQ00/edit?usp=drive_web&pli=1

it looks like R42 is 5.4K

  John

[unc1esteve]

I read of this sketch in my search but could not find it.
I will study it.  I had tried a 5.2k  but it did not start correctly.
Thank you.

[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.

[Chuck in E. TN]

unc1esteve,
I will go see if I can resd the color code on those resistors.
BTW, one of my MC-60's is running my greensand muller also. My muller is a Vontorne derivative, made from a BBQ propane bottle.
Chuck

[unc1esteve]

My mixer is a Rube Goldburg design of scrap materials.
As I have both my rotator cuffs torn I have difficulty lifting
and handling things.  Same with my hands. The idea is to have
a small mixer above table height that can mix, refurbish and riddle
small amounts of green sand directly above the flask.  I am planning to post
pictures on the metal thread if I am successful.
I am using the treadmill controls as I like the sound of the buzzer
and the soft start.  I was going to use the rpm-distance counter as
a visual aid but I lost the item embedded in the motor flywheel.  I
think it is a magnet but am not sure.  No experience with this.  I replaced
the incline controls with a SPDT switch and removed as much of the
plastic housing as I could.  I have tried several pots to replace all the
controls but until I can resolve the mystery resistor I will keep testing
with the original controls. 

[Chuck in E. TN]

I finally got out to the shop to take a closer look at my
MC-60's. The resistor in question is a different value on both controllers. One board is marked Rev J, one is marked Rev E. Funny thing, R42 is clipped on one end on both boards, and the resistor is bent up vertical to the board.! It's not used! Both boards are in service, and both function flawlessly. The Rev J board has R42 in the same position as yours, Rev E board, R42 is near center of the board, on the right side of the big power resistor. Both resistors ar 1/4 watt. Both boards have the label RPS1 next to R42.
I found somewhere on the web, a description of how to defeat the soft start on these controllers. I tried the mod as described, but it didn't work. It involved removing a transistor, if I recall correctly. I reinstalled the transistor. I wanted to be able to set a speed on the mill, and be able to shut it of and restart at the same speed again. Now, I just live with the soft start. It requires turning the speed pot to zero and back up untill the motor starts, and then setting speed. Works the same way as my 7x lathe controller, so I guess it's a good thing, plus I'm used to doing it that way.
I disconnected the muller controller and brought it in side to look at under my magnifier. It's (Rev E) R42 is banded brown, red, black, green, green.
Guess I'm not much help, eh?
Chuck

[unc1esteve]

Any help is good help.  We have established that all mc-60s
are not created the same.  That they will run without r-42 connected.
That the value of r-42 will determine the amount of soft start.
I soldered clip-on leads to its terminals.  I can then clip a resistor
in place to observe the affect of the soft start. 
I added a 2-1 gear reducer and then a 12-1  pulley reduction.
The motor will now full start and run with a full load.
It does not over heat.
Am trying different r-42 values with a full load including water and muller ball.
Right now r-42 = 4.7 k.
One would think that a motor and control for a 250lb person  would
run this mixer but not so.  It would get very hot, could not be touched.
The gear reduction adds unwanted noise.  Maybe a few adjustments
with a bigger hammer will help.
Thannk you.

[JHovel]

Can any of you confirm - or otherwise - that the MC60 Rev J controller is good for 240V AC input? My DC motor nedds 180V for full speed.
Also, in the original treadmill with digital controller (not MC60) there was no choke on the DC (motor) side at all. It seems the MC60 needs a choke from pictures I've seen. What are the values for this choke? in Henry or resistance, wire diameter and approximate physical size of the core?
Very much apporeciated!

[Chuck in E. TN]

Joe, the choke is not needed/used on either of my applications. both my applications use 11oVAC connected to the MC-60 through the original circuit breaker that was connected to the power cord. I see no option on mine to use 240vac input.
I am currently away from home visiting family, but I will look in my notes on this computer to see if the board will allow 240v operation and get back to you.
Chuck

[Chuck in E. TN]

I can find nothing on input voltages in my notes, or in the discussion of this controller online at All About Circuits.

http://forum.allaboutcircuits.com/threads/treadmill-motor-speed-controller-problems.18895/page-2

As all the MC-60 controlled treadmills I have encountered were marketed in the US, I would have to assume you would need a step down transformer to use it on 240v.

Chuck

[John Rudd]

To run the controller from 240 ac would need some rework of the components.....the main diodes and the two scrs would need uprating, then the supply for the 12v rail would need conponent mods too....
It can be done, the KB controllers which are similar are available in two flavours,110 and 240v....but why not buy a suitable controller? Unless of course you like tinkering like me? 

[JHovel]

I like tinkering 
Using a step-down transformer is a no-brainer, but it gives you 90V not 180.....
I did buy a Chinese 240VAC to 180VDC controller, and it works, but the motor makes a very loud humming/cogging noise all the way through the speed range. So it will definitely need some kind of smoothing. I'll try different coils and transformers that I have here, after measutring their coils' inductance. I tried today with a 1.8mH choke, that made no difference.... need something bigger.
The interesting thing to me is that the origina digital controller has NO choke at all, not even very large capacitors. It must be working at very much higher pulse frequency than the Chinese one I got.

[mackn918]

   R42 Resister value For the MC-60 controller is..  *54.9K Ohm. the band colors are [Green-Yellow-White-Red-Brown]
If your motor does not start until the potentiometor is turned about half way replace or resolder r42 for fine motor control over full range.