MK Products Prince XL - Manual (Page 19)

Prince ® XL/Spool Gun Owner's Manual - Page 12
Section E Troubleshooting
All MK Products push-pull guns operate on the same principle. The 115
VAC or 42VAC slave motor in the feeder runs at a fast, constant speed, but
has very low torque; it is always trying to feed more wire than the gun motor
wants, and when the gun motor gets all it wants, it slows the slave motor,
preventing a bird’s nest. Because of the low torque produced by the slave
motor, a brake system is used to prevent wire overrun rather than tension.
The drag adjustment in the spindle is used simply to keep the wire slightly
taut, so it will not unspool while feeding wire.
The 24 VDC gun motor is controlled by a solid state speed control and a
pot located in the gun. The gun motor, potentiometer, and micro switch are
connected to the cabinet/control box via a control cable and an amphenol
connector. If this cable becomes damaged, a variety of symptoms can occur,
depending on which wire(s) break. To test, check each wire for continuity
and shorts.
With the increased torque rating in the current Prince XL motor, it now draws
about twice as much current on start-up as the original Prince motors P/N’s
211-0054 & 211-0056. Even though the duration of start-up is very short,
about 15msec, it is too much for the standard 2A fuse to handle. For this
reason, all 2A fuses in the motor circuitry should be changed to a 3AG 4A
fast blow 250V fuse. This new 4A fuse is sufficient for use on all model
welding guns on the wire feeders, while still providing protection for the
circuitry from any shorts in the motor or motor leads.
This fuse change includes all Cobramatic, Cobramatic II and CobraMig
250/260, WC-1, Torpedo’s, and any other motor circuits powering Prince XL
or Spool Guns.
Remember the micro switch in the gun activates both the 115 VAC or 42
VAC and 24 VDC circuits in the cabinet. Therefore, if the slave motor and
brake solenoid operate, but the gun does not, look more toward the 24 VDC
circuits, speed control, control cable, or the gun motor. If nothing operates,
look more toward the 115 VAC or 42 VAC input, micro switch leads, or micro
switch.