# lathe just stopped



## TOOLMASTER (Sep 15, 2013)

i was pushing it for several hours....motor turns...hums....didn't blow any fuses ect..

the big tubular cap has a bit of a bulge (25uf)

there is a smaller one..but looks ok


what do you think.. cap?

looking at schematic is it a run cap or start...

jet 8x18


----------



## Tony Wells (Sep 15, 2013)

I would suspect the cap. If you have an old fashioned analog meter, like a Simpson 260, you can get an idea of its condition. Before you remove the cap connections for testing, be sure to disconnect the incoming power, etc to make this a safe endeavor. You also should discharge the cap. The proper way to do this is to clip a resistor (I use a 1k 2 watt) across it to bleed it off safely. Most people just jam a screwdriver across the terminals. It may spark so if you do that, don't use your favorite SnapOn for this. If it doesn't spark, that's the first sign that it may be bad. Using your meter, set it to read in the 10k range and measure the resistance of the cap. It should start off with a low ohm reading, then as the current passing through it from the meter, the resistance changes and should go high. Higher the better. As caps charge, they become something of an insulator, very loosely speaking. If it measures open, or very high ohms (true open is infinity, no reading, no meter movement), then it is bad. If it reads low, just a few ohms, and stays low, not charging, it is likely bad. 

On the other hand, some of the newer DMM's have a cap tester built in. Or, some supply houses have cap testers and can test it and sell you a replacement. Your case does sound like a bad cap to me. The DMM cap testers are not the same as the old style bench cap testers that actually used the voltage the cap is rated for. That is more of a real world test and is, IMO much more reliable. But they are better than no test at all. Of course, since you have noticed a bulge, it it probable that you have a problem, so you will either go to a supply house where they can confirm it, or find a way to test it yourself, even if only with a analog meter, and buy online.


----------



## TOOLMASTER (Sep 15, 2013)

I Went back out with my schematic in hand....the 2 wire i saw earlier that are taped off turned out to be the 10 uf cap..that is titled Milling capacitor...NO MILL ATTACHED 


so seeing how the 10 uf was doing nothing i put it in place of the 25 uf...fired right up....so i have to get a new 25 uf..

BUT still the question is ,is it a run or start cap?....i guessing run...  http://www.youtube.com/watch?v=OMd9QkinXz4


there was no spark...i even pushed it against a piece of steel...it started leaking gas pressure...so yup, she's toast

View attachment 60600
View attachment 60601


----------



## UncleRuss (Sep 15, 2013)

I am not up to speed on the chinese stuff as to their practices.  In the good old *U**SA* *start* capacitors are usually in a round "PLASTIC" enclosure while the *run* capacitors are in a oval "METAL" enclosure.  HTH!


----------



## Hawkeye (Sep 16, 2013)

Make sure you get an AC capacitor. DC ones are more common, but won't live long in this application. If you get one at a motor repair place, you should be okay.


----------



## TOOLMASTER (Sep 18, 2013)

all better.  25uf run cap from mcmaster fixed it right up


----------



## TOOLMASTER (Sep 19, 2013)

MOTOR  runs cooler now too...being a new lathe to me i didn't think nothing of it other than it just runs hot...but now it is cooler:thumbzup:


----------

