Changing motor capacitor

[MichaelMouse]

The "points" get welded or burned sometimes.  Bit of folded wet/dry between them does it like new.

[stav]

The rope trick got it started but it popped the capacitor again. All the oil leaked out.

I was about to pull it and then the county mosquito spray truck came down our street so I retreated into the house. As if there would be any mosquitos out with how smokey the air is due to the wild fires we are having.

[DFJarvie]

Take apart and clean it out. As mr mouse said clean the centrifugal switch with a little sandpaper then make sure it clicks back and forth.

[stav]

I disassembled the machine and got the motor where I can work on it. I'll see if I can get to the motor after work tomorrow.

[TDKPE]

If the start capacitor blew while it was running, it's because the centrifugal switch didn't open once up to speed. It would also explain why it started (in your OP) and didn't seem to get to full speed, as the start winding can actually retard the rotor speed beyond a certain point. Like a starting motor on an engine that won't deenergize, and the Bendix won't let go. It's helpful to a point, and a hindrance beyond that.

And it isn't designed for continuous running, unless it's a cap start/cap run motor, in which case only the start cap is cut out, while the "B" winding (start winding) remains in the circuit with the (much different) run capacitor in series with it. But yours doesn't seem to have two capacitors, so that start winding has to be cut out completely, or it can fry, along with the start cap.

Do check for welded contacts, or sticky mechanism.

[stav]

I got the motor open and this is what I found. 



It was pretty clean inside other than a few little chips.  The windings look good as far as I can tell.



And the centrifugal switch part seems ok.  Although, I watched a video from Grizzly and theirs is adjustable on the shaft.  Mine does not appear to move.  



And the points on the static switch appear to be a little corroded. 



Everything seemed to move pretty freely. 

Based on the parts here, it looks like as the motor spins up the black ring on the centrifugal switch moves out towards the static switch and causes the static switch to close.  I guess that is where it disengages the start windings.

[daddo]

You said the motor never seemed to get up to speed. If this happens, the start circuit will remain closed and burn the capacitor.

It may not be getting up to speed because of a start circuit failure, wrong voltage to the motor or a bad winding in either the start or run winding- or a tight motor.  If the start circuit is stuck closed, the motor might reach full speed but quickly overheat.

The burned capacitor is harmonious with voltage being applied too long to the capacitor- which takes you back to the motor not going to 75% speed.

I can tell you what I would do in my shop on the bench. You decide if it is good for you.
I would lightly lubricate the start circuit moving parts and see that the contacts are clean and of course not stuck closed and move freely.
I would then assemble the motor. I would then leave one wire off of the start capacitor. I would then energize 240v to the motor and at the same time touch the open wire at the capacitor to the capacitor for no longer than 2 seconds to simulate the momentary start circuit and see if the motor runs. You could rig a momentary switch for this too- which is much safer!   If the motor runs normally, I know the motor is good and there is/was a problem in the start circuit controls.

 Keep in mind that when taking the motor apart, things are jolted and jiggled and stuck contacts could have been freed during that process.


This capacitor will put off a lot of voltage which will jump a small gap, so protect yourself from this and bleed it off afterwords.

I would say to ohm the run and start windings, but I don't know what the readings should be except that the run windings will have more resistance.

[stav]

Just getting back to this after taking the weekend to clean up after a water heater failure.  If they get to be 25 years old in your house, start to think about replacing them is all I can say.

Daddo, I like the idea you presented, but that thought of connecting the power that way with the limited equipment I have scares me quite a bit.  If I were to go with the switch idea, what kind of switch would be required?

[fredhargis]

I don't doubt the knowledge of those helping you with this, but if the motor is out  I'd take it to a motor shop for diagnosis.

[doobes]

I don't doubt the knowledge of those helping you with this, but if the motor is out  I'd take it to a motor shop for diagnosis.

Kinda tend to agree here.