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-   -   how do I test Capacitor ? (http://www.diychatroom.com/f18/how-do-i-test-capacitor-139079/)

walt1122 04-02-2012 07:52 PM

how do I test Capacitor ?
 
Hi all, refrig not working! Electric getting to the compressor and the klackson?( the overheat bi-metal switch thing) shows contuinity but compressor only hums! Tried to check compressor wiring. I have resistance on both sides so I think both start and run windings are ok so all I have left is the Capacitor ?? Not sure if I remember how to check or if I'm on the right track.

Any help would be appreciated.

thanks

Walt

jbfan 04-02-2012 07:57 PM

Some meters have a capacitance check, otherwise set your meter to 20k ohms, place leads on each post, then swap leads.
You should see the cap charge and discharge.

Works better with an analog meter.

walt1122 04-02-2012 11:14 PM

Hi jbfan, think I have an old Simpson meter (analog) around someplace.

Thanks

Walt

ddawg16 04-03-2012 12:53 AM

Quote:

Originally Posted by walt1122 (Post 890720)
Hi jbfan, think I have an old Simpson meter (analog) around someplace.

Thanks

Walt

As in an old Simpson 260? They work well.

Put it in the 1M range....with the cap removed from the motor....touch the leads....It should show a dead short and then the neddle should move back to open as the cap charges.

Note...this is not a 'solid' test...the voltage out of the simpson is what...maybe 1.5vdc? The cap it designed for 240Vac or higher....there could be a breakdown at higher voltages...

walt1122 04-03-2012 08:54 AM

Hi ddawg16, 260? maybe! Almost the size of shoe-box, black with big screen and couple knobs. Got it somewhere years and years ago but never took the time to learn how to use it with all the digit multi-function digital units around.

Guess I need to find it, clean the dust off, and give it a shot.
I'm calling local parts places today to see if they have a new cap. On the web the parts guys have the replacement cap for $20+- but the delivery time is a couple of days ( unless I spring for another $25 for overnight). So maybe I will just buy the new one and give it a try.


thanks

Walt

walt1122 04-03-2012 09:36 AM

Hi all, ddawg16 I removed cap from circuit, tried at 1m among other points. NOTHING! Meter does NOT move. To test leads and meter I just touched them together and it went all the way to dead short. Looks like the cap may just be the problem.

If anyone has any additional ideas of what I might be overlooking please jump in.

thanks

Walt

J. V. 04-03-2012 10:43 AM

Did you put fresh batteries in the meter? Do you want to sell the meter?

ddawg16 04-03-2012 10:58 AM

Quote:

Originally Posted by walt1122 (Post 890891)
Hi all, ddawg16 I removed cap from circuit, tried at 1m among other points. NOTHING! Meter does NOT move. To test leads and meter I just touched them together and it went all the way to dead short. Looks like the cap may just be the problem.

If anyone has any additional ideas of what I might be overlooking please jump in.

thanks

Walt

If there was NO movement of the meter movement when you connected to the cap....yea....looks like a bad cap. To bad it's not a regular motor....then you could give it a start spin to see if it runs.

Quote:

Originally Posted by J. V. (Post 890918)
Did you put fresh batteries in the meter? Do you want to sell the meter?

Hey...I have first dibs.....

walt1122 04-03-2012 11:03 AM

Not sure what I'm looking at but...I do see a "bounce" when I move the Simpson knob from Rx1 to 1 MA. while connected to the cap? Needle move maybe a 1/16 of an inch to say 250 on the ohms scale. Not sure what this means? if anything?

Cap says 210 VAC 15 uF.

Sure looks like the cap feeds the start AND run circuits The white is the top or common has the overheating relay, then the other two posts on the compressor get the two black from the cap and the third an orange one goes into the same block as the black connectors not sure what all this means. Looking through a book I have but this arrangement doesn't show up as a wiring diagram option.

OK got to be me. Sitting here with the cap in my hand, with the meter on R1 I touched the leads to the cap and got a spark!!!!

Think I have a problem with the meter??
I only get a short ( needle buried to right) on Rx10,000, Rx100, Rx1 NOt on 1 MA., 10 MA., or 100MA.. I think I will have to go looking for that cheap Harbor Freight meter that I think has cap tester.

Plus, if the cap is charging up then I'm still in trouble cause that means it must be something else.

thanks


Walt
1

jbfan 04-03-2012 11:17 AM

Meter needs to be set at rx highest value.

You are not going to test anything with the ma setting

walt1122 04-03-2012 09:26 PM

Yes new battery.

I get a short ( full swing) on the Rx__ function but not on the MA when I touch the leads together. I thought I would get something from any of the functions.

Ordered a new cap and hope this will fix problem. Keep your fingers crossed. With luck maybe I won't be back asking additional questions. But thanks for all the suggestions and help.

Walt

zappa 04-03-2012 10:49 PM

Quote:

Originally Posted by walt1122 (Post 891271)
Yes new battery.

I get a short ( full swing) on the Rx__ function but not on the MA when I touch the leads together. I thought I would get something from any of the functions.

Ordered a new cap and hope this will fix problem. Keep your fingers crossed. With luck maybe I won't be back asking additional questions. But thanks for all the suggestions and help.

Walt

That's correct, only the Rx settings will give a meter movement when the leads are touched together. The ma (milliamps) is for measuring current in series and doesn't use the battery in the meter. When the meter jumped while in the ma setting when you placed the leads across the cap was because you shorted out the slightly charged cap with the meter and it was measuring the current. This could damage the meter if the cap had a full line voltage charge on it.

Reading your thread made me a bit sad that I sold my 260 years back so I just went downstairs to confirm it was really gone. What a pleasant surprise to see that it was still there. When a person starts forgetting what they have means there is too much stuff laying around. :yes:

walt1122 04-04-2012 06:41 PM

Hi zappa, I hear ya' I have more junk than anyone needs. Basement full, 2 car garage full, and couple sheds crammed to the rafters with this-and-that. Mostly broken, rusty I'll get around to it someday projects. Plus we built a 3 car garage in Tennessee that I'm slowly filling with stuff so I can have my "stuff" there too. So I know just what you mean.

Meanwhile, guys I'm lost! I got the new cap and still not working right. So I want to pose a second question; We were away for almost 4 months at our Tennessee home. Could the refrigerator be out of 134a. I have about 125v going to the compressor relay. The start and run wires seem to be run through the cap and I have volts and amperage of about 1 amp through the cap. The compressor is humming and maybe running but hard to really tell. But I got no cooling no sweating no frost, nothing. Sounds strange but could the refrigerator be completely empty?? How can I tell without getting a piercing valve. I'm having trouble trying to figure this out and the wife is getting tired of me scratching my head and keeping food in ice chests.
Any thoughts, suggestions, ideas?

thanks

Walt

qbert 04-04-2012 07:36 PM

Did you ring the compressor out prior to replacing parts? Start to com and run to com should add to the value of start and run. If it checks out they do make a start booster for domestic refrigerators as a last resort. When testing the function of a fridge you test amp draw of compressor and box temperature. Check your schematic and make sure system is sending voltage to compressor defrost timers have been troublesome

walt1122 04-04-2012 08:08 PM

Hi qbert, you are talking over my head. Just a homeowner who has a very limited understanding and a refrigeration and air conditioning book. I tested the start and run wiring to see if they were OK and I had resistance, no shorts found so I figured all was good. I guessed it might be the cap acting up and not kicking on the compressor. That is what brought me here, not being able to figure out how to test a capacitor. Even went so far as to buy a new one but it too made no change in the operation of the refrigerator. I hear the motor hum and if pressed I think it is running just doesn't sound like it is compressing anything. That is why I'm thinking there is no 134a charge but it sounds unlikely that there is NOTHING?? So I'm interested in others thoughts on this as a possible problem or ways to test this theory.

thanks

Walt


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