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What's wrong with this wiring?

http://www.thebrewingnetwork.com/forum/viewtopic.php?f=4&t=28698

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What's wrong with this wiring?

Posted: Sun Aug 12, 2012 2:36 pm
by Quin
So is something wrong here? Just trying to run the motor in one direction.
Have continuity through switch and up to motor on black side.
Continuity from motor black lead to neutral.
120V to switch.

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Re: What's wrong with this wiring?

Posted: Sun Aug 12, 2012 3:12 pm
by siwelwerd
Looks to me like the wire from your switch should be running to the (motor side) terminal of the resistor, not the capacitor (for CW rotation).

Re: What's wrong with this wiring?

Posted: Sun Aug 12, 2012 3:52 pm
by Bugeater
In addition, make sure that you have the polarity of the capacitor correct.

Wayne

Re: What's wrong with this wiring?

Posted: Sun Aug 12, 2012 4:22 pm
by Quin
OK. Reversed the resistor so that the short back wire goes from the capacitor to the resistor and the black wire with white stripe goes from the switch to the resistor to the motor black lead. Still no luck...

There aren't any markings on the capacitor. How do you tell the polarity?

Re: What's wrong with this wiring?

Posted: Sun Aug 12, 2012 5:44 pm
by BDawg
Re: capacitor polarity-

An electrolytic capacitor has "+" and "-" markings on it. The schematic isn't calling for one. If it did, there would be little "+" and "-" signs on the symbol in the diagram, AND on the capacitor. I think its safe to assume then, that this capacitor is NOT electrolytic so it doesn't have a polarity to worry about.

If there was a polarity, based on the straight and curved sides of the capacitor symbol, you'd want to orient the "-" side toward the resistor and the "+" to the red line going to the switch and the motor.

Re: What's wrong with this wiring?

Posted: Mon Aug 13, 2012 4:08 am
by NHbeerscene
I think the flux capacitor needs charging and the finneginn pin needs cleaning :D . Sorry it's all greek to me. If it's a ventilator I am your man but electronics is way out of my league. Good luck though.

Re: What's wrong with this wiring?

Posted: Mon Aug 13, 2012 7:36 am
by gwk453
It looks like a motor from a milling machine which are generally 3 phase, but this is out of my realm of electrical knowledge.
Best of luck!

Re: What's wrong with this wiring?

Posted: Wed Aug 15, 2012 7:59 pm
by ajdelange
This is a biphase motor with white being the neutral and red and black the two phases. The reason there are no polarity markings on the capacitor is because it is not a polarized capacitor i.e. not an electrolytic.

The black wire from the motor should be connected to one side of the switch and one side of the resistor. The red wire from the motor should be connected to the other side of the switch and one side of the capacitor. The remaining terminal of the capacitor should be connected to the remaining side of the resistor.

You should check, with an ohmeter, the resistances between white wire and red wire and between white wire and black wire. These should be about the same. If one winding is open the motor won't run. You should also check that the resistor measures about 150 ohms. If it is open, the motor won't run.

If both windings measure about the same and if the resistor is about the right resistance then suspicion focuses on the capacitor. They do fail. If people knew how often they could fix their own air conditioners by replacing a run capacitor the pros would be out of business. You can try energizing the circuit and then spinning the motor by hand. If it runs, even briefly, that again focuses attention on the capacitor. If your meter has a capacitor check function measure the capacitance (remove it from the circuit first) to be sure that it is about 10 ufd. If not, measure the resistance of the capacitor. If it reads low instantaneously and then climbs to a very high or open circuit reading then all is well (this is hard to see on modern digital meters - the important thing is that it does not show any resistance other than a very high one). Short the terminals of the capacitor and then get a 9 volt battery and connect across the capacitor terminals. Then disconnect and quickly meausure the voltage. If you see some retention of voltage, however brief, then the cap is probably OK. If you pass all these checks and it still doesn't run then it's gremlins.

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