Thread: Motor stopped working on dust collector

If it has one it could be the run/start capacitor.

Have a look on the side of the motor and if it has a bulbous attachment then it has a capacitor

When you turn it on does it make a bit of a humming noise? If so that is a hint that the capacitor is gone.

You can check this by (BE VERY CAREFUL WHEN DOING THIS)
- MAKE sure the motor is turned OFF
- spin the impeller up to a good speed
- quickly turn the motor on and if it starts then its the capacitor

If it is a motor that uses a centrifugal switch then it could be the switching mechanism inside the motor.

Originally Posted by BobL

If it has one it could be the run/start capacitor.

Have a look on the side of the motor and if it has a bulbous attachment then it has a capacitor

When you turn it on does it make a bit of a humming noise? If so that is a hint that the capacitor is gone.

You can check this by (BE VERY CAREFUL WHEN DOING THIS)
- MAKE sure the motor is turned OFF
- spin the impeller up to a good speed
- quickly turn the motor on and if it starts then its the capacitor

If it is a motor that uses a centrifugal switch then it could be the switching mechanism inside the motor.

Hello Bob,

Thanks for the quick reply.

I had a look at the side of the motor yesterday and it indeed has a capacitor (big blue D cell sized ), didn't know until now that's what it was called but hey learn something new every day .

When I turn it on there is nothing, no humming or any noise at all. (that's what made me think its the on / off switch)

Where would I look to check the centrifugal switch? is this something I can do or do I need to take it to a professional?

I don't mind having a go at these things if not too complicated.

Steve

Originally Posted by stevepay

Hello Bob,

Thanks for the quick reply.

I had a look at the side of the motor yesterday and it indeed has a capacitor

Where would I look to check the centrifugal switch? is this something I can do or do I need to take it to a professional?


Steve

gidday Steve it is an either/or scenario. You have no centrifugal switch because you have a capacitor . A trip to your local motor rewinder and he can change it over at minimal cost. Capacitors are measured in microfarad I.e. 25 or 30 uf which will be printed on the side of the capacitor. I suggest a motor rewinder to change it over as the can be a bit tricky to wire up given you only just learned what they are called it is better to get an experienced hand to play with the electrical bit
cheers

Originally Posted by Wrongwayfirst

gidday Steve it is an either/or scenario. You have no centrifugal switch because you have a capacitor . A trip to your local motor rewinder and he can change it over at minimal cost. Capacitors are measured in microfarad I.e. 25 or 30 uf which will be printed on the side of the capacitor. I suggest a motor rewinder to change it over as the can be a bit tricky to wire up given you only just learned what they are called it is better to get an experienced hand to play with the electrical bit
cheers

Ah.. didn't read that very carefully did I

Thanks for the help guys, I'll have a bit of a ring around and see if I can locate someone in my area to do the repair.

Cheers

Steve

Well it seems I can get a replacement capacitor from Carbatec for about 22$ so I'll pick one up this weekend and give it a try, according to the guys there its not that hard to replace and I like a challenge

Cheers

Steve

Originally Posted by stevepay

Well it seems I can get a replacement capacitor from Carbatec for about 22$ so I'll pick one up this weekend and give it a try, according to the guys there its not that hard to replace and I like a challenge

Did you try the spin up test?

Danger......Danger.....Danger

Please read this. It's important, and (maybe) could prevent serious injury or worse.

Capacitors are (sort of) like batteries, and are capable of storing a substantial (even lethal) charge.

The difference is that this charge is fully and comprehensively discharged in the nanosecond a circuit is completed (i.e. a metallic tool or finger across the terminals).

This charge is in the case of some machinery in the thousands or even hundreds of thousands of volts. An old microwave, for example, lying on the tip face may have a lethal 100,000v plus fully charged capacitor waiting to kill the inquisitive. Likewise old TVs.

As a rule of thumb, the bigger the capacitor, the more semiconductive electrolyte, the greater the charge capacity (capacitance). Some old induction motors have big buggers.

Approach with caution.

Originally Posted by Ratbag

Danger......Danger.....Danger

Please read this. It's important, and (maybe) could prevent serious injury or worse.

Capacitors are (sort of) like batteries, and are capable of storing a substantial (even lethal) charge.

The difference is that this charge is fully and comprehensively discharged in the nanosecond a circuit is completed (i.e. a metallic tool or finger across the terminals).

This charge is in the case of some machinery in the thousands or even hundreds of thousands of volts. An old microwave, for example, lying on the tip face may have a lethal 100,000v plus fully charged capacitor waiting to kill the inquisitive. Likewise old TVs.

100,000V is a slight exaggeration. Most Microwaves have transformer V around a couple of thousand volts at most so this is the most the capacitor can charge to, still more than enough to give a decent shock. Some Old TVs had higher voltages but nowhere near 100,000V

The Voltage on a cap on a mains powered motor will usually be no more than 250 V. Still enough to give you a bite and well worth shorting out the terminals before handling it.

Originally Posted by Wrongwayfirst

gidday Steve it is an either/or scenario. You have no centrifugal switch because you have a capacitor . A trip to your local motor rewinder and he can change it over at minimal cost. Capacitors are measured in microfarad I.e. 25 or 30 uf which will be printed on the side of the capacitor. I suggest a motor rewinder to change it over as the can be a bit tricky to wire up given you only just learned what they are called it is better to get an experienced hand to play with the electrical bit
cheers

All of the induction motors (half to say 3 hp) that I have come across have both a Start Capacitor AND a Centrifugal switch. It is the centrifugal switch that switches the start capacitor out of circuit once the motor is up to speed.



The fact that the OP cannot hear the motor buzzing when the motor is switched on suggests it is either the main switch or the armature winding is open circuit.

I would only buy a new capacitor if I can hear the motor buzzing and it still won't rotate. If a manual "flick" test as BobL suggests gets it going, then it is either the Start capacitor or the centrifugal switch.


Trevor

Originally Posted by tgbrooks

All of the induction motors (half to say 3 hp) that I have come across have both a Start Capacitor AND a Centrifugal switch. It is the centrifugal switch that switches the start capacitor out of circuit once the motor is up to speed.

That's interesting because none of the 2 dozen or so single phase motors I have restored have had both a starting cap and a Centrifugal switch.

Originally Posted by BobL

Did you try the spin up test?

Hello Bob,

I will be trying this out tonight when I knock off work.

So just to be clear if I can get it going by the spin up test its most likely the capacitor but if not its probably something else?

For the sake of 22$ I'm not too fussed if I replace it and it still doesn't work because at least I have eliminated that particular possibility.


Steve

Hey guys just a quick update,

I tried the spin up test and it didn't work so I replaced the capacitor and didn't kill myself...

It turned out not to be the capacitor and actually was a faulty connection in the on off switch box which I missed first time around, I basically rewired the box with new connectors and a bit of solder and we were good to go.

I don't regret spending 25$ on a new capacitor as it was a good learning experience and not as hard as some would make it out to be, basically 2 wires and 2 connectors so pretty easy even for me.

Thanks for the help and suggestions guys

Cheers

Steve