Hi,
I have a Proform 770 EKG treadmill that at the moment with a problem on the motor control board. The control board is called a model no. MC-60, which was used in several different makes and models of treadmill; as it turns out I'd scavenged a similar control board and motor at the scrapyard a few years ago, and the treadmill seems to have all functions restored when I swap this board in. However, I'd like to repair the board, as I was hoping to use the spare one (and motor) to power a drill press or something shop related like that.
Hence, having a working circuit board to compare the non-working one to, I'm hoping for some hints that will help isolate the problem component. The motor is powered by 2 SCR's, which are not being triggered. The trigger circuit has an opto-isolator MOC3052, which is supposed to be activated by an op-amp on a nearby LM324, and I'm to the point now that I think the op-amp is bad, from doing comparative diode junction measurements on the two boards.
I wondering if I can confirm the faulty component's identity with my DMM before I start replacing things - I don't have access to O-scopes or anything fancier than a $30 DMM, so I wondering If getting significantly lower readings on the suspect portion of the LM324, would be a valid test (no short circuits, but 40 - or 50% lower mv's on the diode-test scale.
So far I've only found a hand drawn schematic of the MC-60 board, I kind of like the design of it as it has several LED's on it telling what's working and what's not, I'll callcustomer support later in the day to see if they can be of assistance.
Thanks in advance for any help, Mike