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Old 08-21-2018, 08:09 AM   #20
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Join Date: Sep 2008
City & State: NL
My Country: Canada
Line Voltage: 120VAC 60 HZ
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Posts: 474
Default Re: Treadmill DC Circuit no motor start

Originally Posted by R_J View Post
I would think the ic is bad, I can't trace where LG2 goes but it must connect to one of the ic input pins, It seems to go under the ic?
check which input pin it goes to, the speed control should vary the input pin and likewise the output pin
when you connected VCC pin4 to pin3 (in1+), out1 told the rest of the circuit to turn the motor full on. So I still think the ic is bad
R33 will be good
I can't see where the trace for LG2 goes under U2 but I buzzed LG2 to the pins on U2 and I get a signal on pin 3 (all wires disconnected).
I did order a couple of the KA324A IC's off Ebay but may have to get them elsewhere if I need them quickly.
I did notice that discoloration on U2 has now disappeared with all the handling? What effect would R5 have on the speed control circuit? looking at the bottom side of the board it do look like some kind of corrosion there? A couple of new pic.
I also just noticed that I reported voltages on U1 in post #18?? The voltages on U2 should read like this using LG3 as ground;
Pin 1- 0.00
Pin 2- 0.06
Pin 3- 0.00
Pin 4- 11.29
Pin 5- 0.02
Pin 6- 1.02
Pin 7- 0.00
Pin 8- 5.21
Pin 9- 5.21
Pin 10-5.20
Pin 11-0.00
Pin 12- 0.00
Pin 13- 0.002
Pin 14- 0.002

Sorry for the mix-up
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Last edited by davg; 08-21-2018 at 08:53 AM..
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