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oh turds! compressor motor starting cap's 'blown out' but it's a"non-standard"

D

dave

my ancient 4hp sears craftsman air compressor needs a starting
capacitor, I've determined (through a process of elimination). I still
have the original owners manual, and the capacitor is "part of the
motor", not shown in the parts blowup, or parts list, as a seperate
orderable part. further, the friggin' thing seems to be a 'non-standard'
mfd rating, too (it doesn't 'fall into' any capacitor size-groups of any
maker's starting cap's I can find online. matter of fact, it's not even
close):

the one in it now is
110 volt, 485-580 mfd
mallory #139852-49
seems a slightly non-standard SIZE as well:
diameter: 1 13/16ths inch, and
length, overall, excluding 'spades': hair over 4 5/16ths (but clearly
under 4 3/8ths)

atttempts to locate same by the mallory part number on it entirely
unsuccessful. so (physical size and 'look' issues aside) can I "daisy
chain" two cap's and achieve the same net effect, somehow? appearance
"not an issue", I just need a working compressor. I know I can replace
the cap with a higher voltage cap, and that'd be fine (maybe even
desireble) but what about the mfd rating? if I must, is it best to go
'bigger mfd numbers' or lesser?

thanks for tips on this, guys :)
 
D

David Nebenzahl

One trick we used to do in a emergency is to get two DC electrolytic
capacitors of twice the needed AC capacity and connect them in series,
either both + leads or both - leads together and wire the remaining
leads to the motor to replace a single AC capacitor. Gets you going
while you look for the correct replacement.

That can't be safe, can it--running AC through two polarized capacitors?

(Hey: two explosions for the price of one!)
 
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