Hello,
I have trolled and read everything I can find (big thank you to Rom Rollins for the hand drawn MC-60 schematic!) but I cannot figure out what is going on with a Proform J8 treadmill. The belt stutters when you walking. I started down the usual path but it turns out the motor runs (drive belt disconnected) in some kind of open loop but still appears to control the speed somewhat. I feel like I must be missing something obvious.
Proform J8, PB-121 Power Supply Board, MC-60 Motor Control Board, Icon 2.5 HP 130 VDC motor (red, black, and two blue wires)
Observations:
1) with the drive belt off (so no signal from the reed sensor that the walking belt pulley is turning) the motor will still run without going to max speed.
2) the speed changes with the speed changes via the control panel, up and down. It stops driving the SCR's when reducing the speed.
3) I can stall the motor by pressing on the flywheel with my shoe. The current limit comes on at a steady 14amps.
4) the system appears to ignore the signal from the reed sensor.
5) voltage on motor seems to track with speed setting, around 12V at 1mph, 24V at 2mph, 36V at 3mph.
Ok, running in open-loop with no speed feedback would explain the jerky behavior when walking. But this raises two questions.
1) where in the heck is it getting the speed signal to know when to turn the SCR's on and off? It is not just firing at a fixed angle verses speed setting because it will coast with no SCR firing until the speed drops when you lower the speed.
2) why does the system not drop into an error condition after X amount of time with no signal from the tach. (I am not going to change any firmware on the interface panel so this is more of a philosophical question)
I cleaned the brushes and the contact area just for good measure with no impact. Any suggestions on closing the control loop short of replacing the interface panel?
Thank you,
-Shane
I have trolled and read everything I can find (big thank you to Rom Rollins for the hand drawn MC-60 schematic!) but I cannot figure out what is going on with a Proform J8 treadmill. The belt stutters when you walking. I started down the usual path but it turns out the motor runs (drive belt disconnected) in some kind of open loop but still appears to control the speed somewhat. I feel like I must be missing something obvious.
Proform J8, PB-121 Power Supply Board, MC-60 Motor Control Board, Icon 2.5 HP 130 VDC motor (red, black, and two blue wires)
Observations:
1) with the drive belt off (so no signal from the reed sensor that the walking belt pulley is turning) the motor will still run without going to max speed.
2) the speed changes with the speed changes via the control panel, up and down. It stops driving the SCR's when reducing the speed.
3) I can stall the motor by pressing on the flywheel with my shoe. The current limit comes on at a steady 14amps.
4) the system appears to ignore the signal from the reed sensor.
5) voltage on motor seems to track with speed setting, around 12V at 1mph, 24V at 2mph, 36V at 3mph.
Ok, running in open-loop with no speed feedback would explain the jerky behavior when walking. But this raises two questions.
1) where in the heck is it getting the speed signal to know when to turn the SCR's on and off? It is not just firing at a fixed angle verses speed setting because it will coast with no SCR firing until the speed drops when you lower the speed.
2) why does the system not drop into an error condition after X amount of time with no signal from the tach. (I am not going to change any firmware on the interface panel so this is more of a philosophical question)
I cleaned the brushes and the contact area just for good measure with no impact. Any suggestions on closing the control loop short of replacing the interface panel?
Thank you,
-Shane