On May 18, 5:48*pm, robgraham wrote:
On May 18, 12:49*pm, Andy Dingley wrote:









On May 18, 12:20*pm, robgraham wrote:

Further guidance now sought - I've got the capacitor off, but am
puzzled by its working voltage of 125vac (capacitance of 200mfd). *

Jet tools - US spec electrics. We no longer get the toggle switch
controls with no NVR, but we do still get vibration-sensitive magnetic
latches that wear out in 6 months, motors that overheat at 50Hz and
these capacitors that are under-specced for their actual use. Let
alone the abyssmal standards of construction and reliable earth
continuity on most US-built kit. A lot of US kit simply isn't safe on
arrival

Working voltage on capacitors like this doesn't mean that they'll fail
instantly at anything over this, it's more of a design working voltage
to achieve an adequate life. As you've discovered, when used in Europe
the result tends to be a functional unit on arrival, but with an
inadequately short lifetime.

I suggest fixing it by replacing the capacitor - it's easy to find
replacements from anyone who deals with power electrics or motors.

I'd also suggest a complaint to jet and to your retailer. This
American electrical farce has gone on for far too long. China doesn't
try to sell this sort of under-spec kit any more, why should the US
get a free ride?

Andy
So far I'm impressed by the earthing on this machine and the quality
of the build, NVR , etc. *The reason that the capacitor is 125vac is,
I'm told, nothing to do with US specced machines but is a cost cutting
design where the start winding is tapped into the main winding such
that the main winding acts as an autotransfomer and the start winding
only sees 125v. *The cost of making 125vac *capacitors is considerably
less than that of 250vac for the same capacitance (verified by the
price per item on Ebay) and the greater capacitance required has a
considerably less significance on the end price.

The problem may be the capacitor, but the large capacitance and the
lower voltage does back up the info I am receiving. *Nothing has
convinced me as yet to be suspicious of the design or materials.

Rob

A new idea has been put forward on this one and it would be
interesting if anyone has any comments on it.

Bearing in mind that the starter winding is not a totally separate
winding but tapped into the main winding auto-transformer wise, the
possibility has been suggested that a back emf / induced voltage is
appearing across the starter windings that is in the opposite phase to
the mains voltage and therefore is adding to the voltage across the
capacitor and leading to it's breakdown - the randomness of the motor
current overload tripping could be explained by the point in the mains
cycle that the machine is switched on.

Plausible ?

Rob