© 2016 Nelson Stud Welding, Inc.
Page 24
All Rights Reserved.
February 2016
Part No. 729-110-042 v1.03
7.3 Electrical Functions of Guns
7.3.1
Coil Power Circuit
Check the coil circuit by connecting an ohmmeter parallel to pins 2 and 6 in the control plug. The resistance
should be about 240 ohms cold and 275 ohms while hot. The Contact gun does not have a coil.
7.3.2
Triggering Contact
The trigger switch is checked for proper functioning by connecting a continuity tester or ohmmeter at pin 3 of the
control plug and to the foot plate.
If the switch provides a proper contact, the continuity tester will emit a signal or the ohmmeter will show 0 ohms.
7.4 Gun Coding
A jumper between pins 1 and 6 tells the power unit that a set lift gun is connected. An ohmmeter will show 0
ohms.
7.4.1
Dismantling & Reassembling Gap & Contact Welding Guns
1
Loosen set screws in the front cap 2 and rear cap 1.
2
Remove the caps and lay the gun on its right side.
3
Remove 3 screws that hold the gun halves together.
4
Separate and remove the left gun body such that the internal components remain in
the right half.
5
Inspect parts for damage or excessive wear and replace if necessary.
6
Reassemble in reverse order; making sure that the radial orientation
of the holding coil assembly 8 is such that where the leads emerge
from the coil is adjacent to the slot in the right gun body so the leads
can be neatly run into the gun handle. The spring adjusting nut 5
should be oriented such that the radial screw fits in the keyway in the
gun body and the spring tension gage line is toward the top of the
gun.
7
Reassemble the rear cap with the slot towards the top of the gun
and the front cover with its bottom perpendicular to the gun handle.
Wire Code
Pin #3
Trigger
Pin #4
Trigger
Pin #5
Gun Coil
Pin #6
Gun Coil
Located in Gun Handle
White
Trigger
Black
Trigger
Brown
Weld Cable
Blue
Safety Bypass
(Spring to Front Cover)
Green
Coil
Red
Coil
