Re: Treadmill DC Circuit no motor start
The speed control should vary the voltage on LG2 from 0 - 5 volts, If it is connected to pin 3 of U2 I would expect more than 0 volts on that pin. You need to check the resistance between LG2 and pin 3, (buzzed has no value) is it 0Ω
Do you still have 5 volts on LG1 if you do, you should have ie: 2.5 volts on LG2 with the speed control set to the middle.
You said you shorted pin 3 & 4 and the motor ran full, that tells me if there is a higer voltage on pin 3 the circuit should work. That slipp of the probe may have also damaged the speed pot, so check its resistance through its full range
R5 is should be a minimum or maximum speed set, likely sets motor stop when speed control is at minimum.
Now with the new voltages and the top of the ic not looking like it is damaged, the ic could be ok.
From post #13
Where is the speed control set when you are checking these voltages?
The speed control should vary the voltage on LG2 from 0 - 5 volts, If it is connected to pin 3 of U2 I would expect more than 0 volts on that pin. You need to check the resistance between LG2 and pin 3, (buzzed has no value) is it 0Ω
Do you still have 5 volts on LG1 if you do, you should have ie: 2.5 volts on LG2 with the speed control set to the middle.
You said you shorted pin 3 & 4 and the motor ran full, that tells me if there is a higer voltage on pin 3 the circuit should work. That slipp of the probe may have also damaged the speed pot, so check its resistance through its full range
R5 is should be a minimum or maximum speed set, likely sets motor stop when speed control is at minimum.
Now with the new voltages and the top of the ic not looking like it is damaged, the ic could be ok.
From post #13
Originally posted by davg
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