The
fine print: T. J. Snow assumes no liability by you following these
directions. You do so at your own personal risk, and at the risk of damage
to your equipment. If something goes wrong, you cannot hold us liable.
If you cannot accept these limitations do not proceed with these tests.
The tests described below utilize
an ohmmeter. A regular unit will pick up most shorts, but a mega-ohm meter,
if available, will work better. Later steps also ask you to use a fused
110 VAC power cord. Make sure the cord is fused with a ~5 amp fuse. As
always, exercise due care and caution when working around live electricity.
Make sure that the power to the welder
is disconnected and the power is locked-out according to plant approved
lockout-tagout procedures.
Disconnect the line leads running from
the transformer or tap switches to the control.
If the transformer has a tap switch
connected to it, make sure that it is on a tap and not in the “off” position.
Connect the ohmmeter across the line
leads that you disconnected from the control. You should read zero ohms,
or “continuity”, through the primary of the transformer.
Next connect the ohmmeter between either
line lead and the secondary of the transformer. You should read infinite
ohms, or “no continuity”.
Now connect the ohmmeter between either
line lead and the ground (or frame) of the transformer. You should read
infinite ohms, or “no continuity”.
Turn all tap switches to their highest
setting.
Make sure that the weld tips, or secondary
of the transformer is an open, not complete, circuit. This can be accomplished
by placing a piece of rigid insulation or an old credit card between the
tips.
Connect the fused 110 VAC cord across
the two line leads. Note: If the windings of the transformer are bad, you
will probably blow the fuse in the 110V cord.
Check the Secondary output voltage of
the transformer with a voltmeter. This measurement should be made right
at the transformer, and not at the tips. Bad connections in the secondary
loop could cause a larger voltage drop across them. Also make sure that
the secondary loop is still open (above) or the transformer will be under
a load.
If your welder has a 220 VAC supply,
you should read about ½ of the rated maximum secondary voltage.
If your welder has a 440 VAC supply,
you should read about ¼ of the maximum rated secondary voltage.
If the voltage reading is close, your
transformer is probably good.
If you have a clamp type ammeter, you
can check the primary current draw of the 110V line. It should be no more
than 1 to 2 amps for most transformers.
If you have any questions, feel
free to call T. J. Snow’s transformer experts at 423-894-6234.
at TJS