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F-22
TROUBLESHOOTING AND REPAIR
F-22
6. Locate leads #626 and #627 at the
relay board.
7. If a variable voltage board is
installed in the LN-8, make cer-
tain the mode switch is in the CV
position.
8. Apply 115VAC to the input recep-
tacle at pins C and D.
9. With the gun trigger activated or
the gun trigger terminals jumpered
together, (see wiring diagram),
check the motor armature volts at
leads #541 (+) and #539 (-).
Normal is 5 to 95VDC dependent
upon the setting of the wire feed
speed control.
10. With the LN-8 at idle (gun trigger
NOT activated) check the motor
field voltage at lead #626 and
#627. Normal is 115VDC. When
the gun trigger is activated or the
gun terminals jumpered together,
Figure F.6, the field voltage polari-
ty should reverse from the idle
state. Normal is 115VDC and is
independent of motor speed.
Note: The wire feed direction switch
(S3) must be in the forward, or “weld-
ing” position.
11. If the above voltages are present
and motor does not operate, the
motor, motor brushes, or the gear
box may be faulty. If the armature
voltage is not correct (leads #539
and #541), the control board may
be faulty. If the field voltage is not
correct (leads #626 and #627), the
1CR relay or relay board may be
faulty.
DRIVE MOTOR TEST (continued)
FIGURE F.6 – GUN TERMINAL JUMPER LOCATIONS
LN-8
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1CR
RELAY
627
626
7 529 32A 524(A) 525(A)
LN-8 RELAY