Backward Engineering AC motor wiring

[bladecrasher]

Hello,

I know almost nothing about electric motors, other than low volt DC is safe and AC can kill.

My 12yo child and I are building a project involving an air-pump. We scavenged a low pressure pump off an old Xerox production (135 ppm) laser printer at my work that was being tossed out. The motor Fasco Ind. 115v 60 hz and has the two air pumps on either side of the motor, with tubing on top that connects the two pumps to provide one air intake and one output.

I found some Fasco wiring info, but none of the wires match what this motor has. Being that it was probably OEM'ed for Xerox, maybe they do their own wiring thing. I asked our Xerox service tech if they would show me their fix-it details on their laptop, but due to liability they said no. Weenies, but hey I'm not offering any $$.

The motor has 5 wires coming out of it. 1-Green (ground which I can see in the case). 1 - Blue 1 - Brown and 2 - Black with no other marks on the covering. The Fasco PDF attached "almost" shows this as maybe a 2 speed (blue = med) but not quite.

Is there anyway to determine how to wire up the leads to make this thing run?

I checked the resistance between the various wires and labeled the black wires 1 and 2 with tape, and got the following:

Green - (all other wires) - Open circuit

Blue
Brown: 3.4 ohms
Black1: 0.3
Black2: 15.6

Brown
Black1: 3.0
Black2: 12.7

Black1
Black2: 15.5

I can send a photo but it doesn't show much. There is no wiring diagram.

Thanks for your thoughts and suggestions.

Blade...

 

[RODALCO]

I would say the high R winding (blue-black2) is the start winding the low R winding (blue-brown) is the run winding.

The (blue-black1) may be a Voltage tap for 100 or 127 Volts.

For testing put a 100 Watt lamp in series with the motor. It will limit the current to just under 1 Amp in case you short something out.
Try out the wire combinations and see what works best.
If all fine, remove lamp and apply full Voltage and see what happens.
Ensure that the motor casing is earthed, just for your own safety.
Unplug from wall before altering your wires.

 

[bladecrasher]

Test light in circuit, no go.

Rodalco: Now I'm confused.

I hooked up the testing like you outlined. I used the blue wire to one side of a 120w bulb, and the other side of the bulb to the power plug. I then connected the brown wire to the plug and plugged it in. Blub was bright. No motor. I then moved the brown to Black2 - same result. Then Black1, same result.

I next moved the blue wire to light lead to the brown wire, and retested the two black leads on the other side of the circuit. Same result. Light glows, no motor.

I then moved the light side to Black1 and the other to Black2, no motor, just light.

I'm starting to think this is not a 115v motor like it says.

Any other thoughts before we attempt to toss out the motor and find a new motor to run the air-pumps?

 

[shortbus=]

It won't start without the "start capacitor". Or at least it won't start on its own, may start if the shaft is manually rotated, but unlikely with compressor/pump connected.

 

[bladecrasher]

Back to my original question then. Can it be determined what type of start capacitor I might want to try finding and how to wire it in given the unknowns.

Any suggestions?

 

[crutschow]

Back to my original question then. Can it be determined what type of start capacitor I might want to try finding and how to wire it in given the unknowns.

Any suggestions?

I would suggest you try to find a Fasco motor of about the same physical size as your motor and see what value cap they use. That value should be close enough.

As to the wiring, that's a bit of puzzle. The Blue does seem to be connected to Black1 which is odd. Otherwise I don't have any good suggestions.

 

[RODALCO]

Just wondering if the motor may have a centrifugal switch inside which may be connected across the 0.3 ohms reading
Try a 22 uF 400 Volt start cap. and switch it off when the motor runs.

Often result have to be found with trial and error. In case the motor goes up in smoke, only time is lost and you are an experience wiser.

 

[shortbus=]

Back to my original question then. Can it be determined what type of start capacitor I might want to try finding and how to wire it in given the unknowns.

Any suggestions?

The bottom of page 2 in your attachment, page36-38.pdf, says to use a "5MFD 370VAC capacitor"