# How To Test A Capacitor



## 2500Ram (Oct 30, 2005)

Way off topic but I thought I'd ask.
Our pellet stove Quadrafire 1100i took a dive and isn't working. Everything and everyone said the board was bad so I replaced the board again, 2nd board in 2 years. Well the stove still isn't working. First board acts just like the new board. The call light for heat is on but the exhaust fan is not working, spinning VERY slow. The auger feed for the pellets is vacuum fed and if you suck on the hose the auger will start and eventually the igniter will fire but there is no exhaust fan = stinky smoke in the house.

Fast foreword I believe I have a bad startup capacitor but don't know how to test it. I've been all over the web and people say you can test them with a volt meter and other say you can't. I have 2 capacitors on the stove; while the stove is plugged in one will read 130.xx volts and the other .01volts AC. I tried using the ohm reading but don't know what I'm looking for. Everyone says just run down to Radio Shack and get a new one but I don't know if it's bad or if it's the fan but doubt they would have one anyways.

Thanks in advance.

Bill.


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## johnp (Mar 15, 2004)

Bill
On my friends stove the problem was the motor. As far as the capacitor the one reading 130 is good and the other one may or may not have power to it. If your lucky a bad capacitor will have a buldge or split in it. I don't think the exhuast blower motor would have a speed control on it. Check the voltage on the motor if its 120 the motor is junk or if your lucky oil the bearings.The blower should spin freely any drag and the little motor will not spin.

John


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## 2500Ram (Oct 30, 2005)

johnp2000 said:


> Bill
> On my friends stove the problem was the motor. As far as the capacitor the one reading 130 is good and the other one may or may not have power to it. If your lucky a bad capacitor will have a buldge or split in it. I don't think the exhuast blower motor would have a speed control on it. Check the voltage on the motor if its 120 the motor is junk or if your lucky oil the bearings.The blower should spin freely any drag and the little motor will not spin.
> 
> John
> [snapback]67270[/snapback]​


Thanks John, there is no drag on the motor and both caps are in working order. Just for the record you can not test a cap with volts you need ohms. The process as told to me was to disconnect all power to the posts, get a short piece of wire and short the posts. With your ohm meter set to 200k. Put the negative lead on and while watching the meter touch the positive post. You will get a quick readout and then open again on the meter if they are good, if bad they will stay open the entire time, repeat the shorting of the posts between reads.

Anyone have $250 for a new blower motor









Bill.


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## Katrina (Dec 16, 2004)

It's easier to check a capacitor with an old analog meter then with a digital one. Disconnect power to capacitor, short a piece of wire or a screwdriver between the posts on the capacitor. These things can store a charge and shock you pretty good other wise.
With your analog meter set on the highest ohms scale, touch the leads to the posts of the capacitor. Watching the meter, you should be able to see the needle rise and then slowly fall back as the capacitor charges.
Usually with a bad one, the needle will not move at all.
Any good electric motor repair shop should have an actual capacitor tester and check these for free.
Since the caps cost about 8 bucks, I would change them anyways before buying a new motor.


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## 2500Ram (Oct 30, 2005)

Katrina said:


> It's easier to check a capacitor with an old analog meter then with a digital one. Disconnect power to capacitor, short a piece of wire or a screwdriver between the posts on the capacitor. These things can store a charge and shock you pretty good other wise.
> With your analog meter set on the highest ohms scale, touch the leads to the posts of the capacitor. Watching the meter, you should be able to see the needle rise and then slowly fall back as the capacitor charges.
> Usually with a bad one, the needle will not move at all.
> Any good electric motor repair shop should have an actual capacitor tester and check these for free.
> ...


here is my reply on another board regarding the analog vs digital meter, agreed it is better to use analog but it will work with digital.


> Ok, last check. No smell what so ever, I pulled all connections from the cap's and shorted with a small piece of wire. Set the ohm meter to 200k witch left me a reading of 1xx. (x = spaces on the meter or no value) Put on the neg probe and while watching the meter put the positive probe on and had a reading from 130.0, 084.0 to the 1xx. within a second.
> 
> Just about the same readings on the other cap. I had to short the posts each time or the meter wouldn't move but after I had shorted the caps I received the same results each time.


Thanks again.
Bill.


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## PDX_Doug (Nov 16, 2004)

All I can say is, be very careful when messing around with those things, they can really pack a wollop! As in lethal!









Happy Trails,
Doug


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## 2500Ram (Oct 30, 2005)

PDX_Doug said:


> All I can say is, be very careful when messing around with those things, they can really pack a wollop! As in lethal!
> 
> 
> 
> ...


But isn't that where the fun begins









Seriously yes they can but these aren't that big or carry that much of a charge.

Hey honney can you get me thaaaaaaaOOOOOUUUUUUCCCCCCCHHHHHH!!!! sunny

Just kidding.

Bill.


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## CamperAndy (Aug 26, 2004)

This goes even more off topic but it reminds me of the good old days when the ignition system in our cars had points and capacitors.

In shop class you could charge a capacitor with a battery then toss it or hand it to an un suspecting class mate and then watch him dance. After a while we did not even charge them as it was just as much fun watching people try to get out of the way of them since they thought they were charged.

Good luck but I suspect the motor brushes or the bearings.


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