MK Products Cobra System III Gooseneck - Manual (Page 21)

Cobra Gooseneck Owner's Manual - 8/96 Page 16
TROUBLE-
SHOOTING
Regardless of which torch or feeder used, all M.K. Products’ push-pull guns operate
on the same principle. The 115 VAC slave motor in the feeder runs at a fast, con-
stant speed, but has very low torque. It is always trying to feed more wire than the
torch motor wants, and when the 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 adjust-
ment in the spindle is used simply to keep the wire slightly taut, so it will not pull off
the spool while feeding wire.
The high torque 24 VDC torch motor is controlled by a solid state speed control and
a pot located in the torch. The torch motor, potentiometer, and micro switch are
connected to the cabinet/control box via a control cable and Amphenol. 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.
Remember, the micro switch in the torch activates both the 115 VAC and 24 V
circuits in the cabinet. Therefore, if the slave motor and brake solenoid operate, but
the torch does not, look more toward the 24 V circuits, speed control, control cable,
or the torch motor. If nothing operates, look more toward the 115 VAC input, micro
switch leads, or micro switch.
TESTING THE TORCH
A. Motor Check
1. Remove the torch connector from the cabinet.
2. Using the torch Amphenol, check the resistance across pins “A” and “B” (motor
leads). The resistance across the motor should be between 5-10 ohms.
3. If an open circuit or short exist, check the motor leads and motor independently.
B. Testing the Potentiometer - “W” Clocked
1. Using the torch Amphenol, check the resistance across pin “D” (wiper) and pin
“C”. The resistance should vary from 0 - 5K ohms.
2. Check the resistance across pin “D” (wiper) and pin “G”. The resistance should
vary from 5K - 0 ohms.
C. Testing the Potentiometer - “S” Clocked
1. Using the torch Amphenol, check the resistance across pin “D” (wiper) and pin
“C”. The resistance should vary from 0 - 5K ohms.
2. Check the resistance across pin “D” (wiper) and pin “A”. The resistance should
vary from 5K - 0 ohms.
D. Testing the Micro Switch
1. Using the torch Amphenol, check for continuity across pins “E” and “F” when
the trigger is pressed.