Microwave fan wiring?

Thread Starter

wayneh

Joined Sep 9, 2010
17,496
I've just stripped a microwave of parts as it moves towards the recycler. It had a bad PCB and wasn't worth fixing.

The vent fan is identical to the one here. It's marked 120V and has three wires, blue, orange and yellow. The blue wire is slightly larger gauge than the other two. The prongs on the motor terminal connect to blue, orange, yellow, in that order.

I'm fairly certain the fan acts as a transformer and provides 21V AC for the turntable motor, with the other two being mains AC. But which is which?
 

Thread Starter

wayneh

Joined Sep 9, 2010
17,496
Oops. I think I just destroyed it. I tested the yellow and orange pair and this made the fan run. But the windings got hot and now there is no continuity between any poles.

I couldn't get it to run with blue plus either of the other two. Maybe it's possible that the microwave failed because the vent fan died?
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
It could be the transformer type, also if 3 wire it is can also be a PSC induction motor that requires a 6 to 10 micro farad cap.
Max.
 

#12

Joined Nov 30, 2010
18,224
Yes, choke = inductor. especially in a DC power supply.
Those are so old that I'm not sure I have a schematic for one that uses the speaker for a DC choke.
 

debe

Joined Sep 21, 2010
1,389
Yes it is & its the same as the one waneh has, exept mine is a 240v ac motor. These motors with the 21V tap are common in microwave ovens.
 

Thread Starter

wayneh

Joined Sep 9, 2010
17,496
Since I couldn't get it to turn except by using the 21v, which promptly burnt out, I guess it wasn't much good anyway.
 
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