Treadmill Motor Help Needed

fahrphrompuken said:
I think you would want a switch to power off on the AC in so that nothing is energized when it's "off". The speed at start-up will be wherever the pot is set to. If the pot is set half-way when you turn it off, and it has not been moved, then when you power it back up, it should go to the speed that it was with the pot at half-way. There is no need for a speed sensor unless you want to measure the speed, but it's not required to run the unit, that was just needed when it was living as a treadmill.
Click to expand...
No, some boards if you shut the A/C input off with ,say the pot set at 1/2 way, and turn the power back on, it will not run till you dial it down to Zero, and back up. My merrimac board , that came off a tread mill, on my drill press is like that.
Now the KBIC 120 boards I have, will start where ever you shut them off.
 
mrbreezeet1 said:
No, some boards if you shut the A/C input off with ,say the pot set at 1/2 way, and turn the power back on, it will not run till you dial it down to Zero, and back up. My merrimac board , that came off a tread mill, on my drill press is like that.
Now the KBIC 120 boards I have, will start where ever you shut them off.
Click to expand...

First off, Domo Arigato Gozaimasu to Kernbigo. I was recently given the "business end" of a treadmill, and using your info, got it to run nicely on the bench earlier today. Your schematic and picture of the MC-60 were right on, and easy to follow! PS - didn't have a 5K pot ... but a 10K I'd bought from Radio Scrap before they closed is working just fine!

Mrbreezeet1 - Yup, you're right about the MC-60 board's behavior. But (as others have pointed out) if you put a switch in the white (wiper) wire between the pot and the board, leave it open when you first power up, and then close it, the motor does resume whatever speed you'd last set (with some hesitation, as Randy observed in an earlier post). No need to dial down, etc.

Is the KIBC 120 board from a more modern treadmill, or is it a generic DC motor control board? Does sound nice!
 
More modern I think, Its a 120 A/C input, they have one thats KBIC 225 or something like that. Takes 220 though.
I thing it's duel powered, 90 vdc at 120 Vac, and 180 VDC at 220 VAC,
Yeah, I might break the center on the pot if I use this MC-60. I just burned it up, 2 of the PC tracks, but was able to repair it.
I got lucky, I know very little about electronics.
Yeah, I have used a 10K pot on there boards, it seems fine.
The merrimac actually calls for a 10K pot. I really don't know what the difference is. I have a 200 K one, I am gonna try, just to see what the result is.
https://www.galco.com/buy/KB-Electronics/KBIC-120
kbic-240d_p1.jpg
 
mrbreezeet1 said:
Yeah, I have used a 10K pot on there boards, it seems fine.
The merrimac actually calls for a 10K pot. I really don't know what the difference is. I have a 200 K one, I am gonna try, just to see what the result is.
https://www.galco.com/buy/KB-Electronics/KBIC-120
Click to expand...
My Mistake, It is a 250 K Pot I had.
Seems to work fine too.
I don't understand?
That is a big difference, 250K vers. 5K?
 
These motor controls appear to use the pot as a simple voltage divider/source. So the actual value of the pot (within limits, as explained below) shouldn't be a big issue. The "ends" of the pot are supplied with ~12 volts DC, and the wiper picks off whatever fraction of that 12 volts it's physically set to, and sends the voltage to the "wiper" terminal. Side note - the fancy computer controls [an actual 8086 on mine] that interface with the user kinda "bypass" the whole pot issue and (as far as I can tell) simply supply an appropriate voltage to the "wiper" terminal.

Again there are some limits to the resistance value of the pot. Too low a value, and the pot can load down the voltage supply and/or start getting warm from too much power passing through it. Too high a value, and the amount of current the pot can supply to the "wiper" terminal might not be enough to drive whatever circuitry is using the signal. This would show up as a non-linear response of RPM vs knob position. There might possibly be an issue with electrical noise as well.

I'd not worry about any pot value anywhere between 1K and 100K. If your 250K works reliably and is immune from electrical noise and non-linearity, that's wonderful. If you do see a problem later on, you can substitute a lower resistance pot very easily.
 
Yeah, l just had the 250 K one laying around.
I have to find a better source, as I have had two bad ones from Radio Shack already.
Where can I but a quality Pot?
thanks,
Tony.
 
hman said:
These motor controls appear to use the pot as a simple voltage divider/source. So the actual value of the pot (within limits, as explained below) shouldn't be a big issue. The "ends" of the pot are supplied with ~12 volts DC, and the wiper picks off whatever fraction of that 12 volts it's physically set to, and sends the voltage to the "wiper" terminal. Side note - the fancy computer controls [an actual 8086 on mine] that interface with the user kinda "bypass" the whole pot issue and (as far as I can tell) simply supply an appropriate voltage to the "wiper" terminal.

Again there are some limits to the resistance value of the pot. Too low a value, and the pot can load down the voltage supply and/or start getting warm from too much power passing through it. Too high a value, and the amount of current the pot can supply to the "wiper" terminal might not be enough to drive whatever circuitry is using the signal. This would show up as a non-linear response of RPM vs knob position. There might possibly be an issue with electrical noise as well.

I'd not worry about any pot value anywhere between 1K and 100K. If your 250K works reliably and is immune from electrical noise and non-linearity, that's wonderful. If you do see a problem later on, you can substitute a lower resistance pot very easily.
Click to expand...
But in other words also, the 250 Pot will not hurt anything?
 
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