Capacitor question

[kenmac]

Do you need to discharge the capacitor first?

Just put a screwdriver across the terminals it will short it out/ discharge

 

[Soundguy]

Not saying that you are wrong, but after 38 years servicing air conditioners, I have never found a capacitor that was defective and checked out ok with this test.

And I'm not saying that you are wrong.. just saying that a cap that was rated at XX MF might be at XX -10% and the meter current charge test won't show much difference once the electrons stop flowing... however in the long run.. motor issues might crop up unless the cap outright fails later on and is replaced .. etc.

soundguy

 

[kenmac]

Not saying that you are wrong, but after 38 years servicing air conditioners, I have never found a capacitor that was defective and checked out ok with this test.

I like the ones that look like their about to explode

 

[Soundguy]

The 'dead possum bloated on the side of the road' look.. especially with some seepage at the connection lugs/spades..

I use a slightly restive bleeder brobe to discharge caps.. I'm not a fan of the screwdriver method.. I've seen mor ethan one tool arcwelded to a cap.. not to mention the really big ones can discharge enough to melt things..

soundguy

 

[JerryG]

Thanks. I will give the test a try.

 

[kenmac]

The 'dead possum bloated on the side of the road' look.. especially with some seepage at the connection lugs/spades..

I use a slightly restive bleeder brobe to discharge caps.. I'm not a fan of the screwdriver method.. I've seen mor ethan one tool arcwelded to a cap.. not to mention the really big ones can discharge enough to melt things..

soundguy

Sometimes I'll just discharge them with my tongue. Ya know like testing a 9 v batt . No wonder i don't have any taste buds left. They are all burn off
Years & years of working on A/C units


seriously , your meter will also discharge the cap . If it's good and you touch the spades with the meter the meter will go over( non digital meter) & then fall back . You have discharged the cap. Then, just test with meter again & watch the needle

 

[schmism]

i have a HF pancake that has served me for an embarissing amount of time. (going on like 5 years now)

the only issue ive had is i melted the contacts on the pressure switch. i swapped with the one off my junk crapsman compressor that died and have been useing that one.

it reallly is time for me to upgrade to a real one......

 

[Soundguy]

My ohm meter is a tad too expensive to apply it to live voltage sources.. IE.. i don't try to measure the impeadance of a charged cap with it... I got to much practice fixing meters in school when some of the doofi ( plural of doofus ) would try neat tricks like measuring the impeadance of wall outlets and such.. etc.

I'll leave the ohm scale testing of charged devices for those with the cheap consumer grade vom's

soundguy

seriously , your meter will also discharge the cap . If it's good and you touch the spades with the meter the meter will go over( non digital meter) & then fall back . You have discharged the cap. Then, just test with meter again & watch the needle

 

[kenmac]

My ohm meter is a tad too expensive to apply it to live voltage sources.. IE.. i don't try to measure the impeadance of a charged cap with it... I got to much practice fixing meters in school when some of the doofi ( plural of doofus ) would try neat tricks like measuring the impeadance of wall outlets and such.. etc.

I'll leave the ohm scale testing of charged devices for those with the cheap consumer grade vom's

soundguy

I own 1 good fluke volt meter that I do most of my testing with. I use the cheep ones to test capacitors with. I loose alot of the cheap meters, burn them up, drop them, get them wet, etc,. That's why I buy the cheap ones by the dozen. Anyone but me do the tongue test ? It does work on the bad ones

 

[Soundguy]

I own 1 good fluke volt meter that I do most of my testing with. I use the cheep ones to test capacitors with. I loose alot of the cheap meters, burn them up, drop them, get them wet, etc,. That's why I buy the cheap ones by the dozen. Anyone but me do the tongue test ? It does work on the bad ones

I guess I could wait till harbor freight has the cheap voms on sale for 2.99 ( down from every day low price of 4.99 ).. but I just can't move myself to buy a meter so cheap. i'd always wonder if it was accurate... IE.. if it was close enough tolerance to let me do things without letting smoke out of other parts.

I have a small collection including a single analog meter for checking dc generators, 2 precision digitals, one with scope... and a couple of decent cheap vom's ( 50~70$ ) auto rangers. .. that's about as low as i want to go and still trust what the face of the meter says.

soundguy