Lincoln Electric 11519 Service Manual page 75

F-29
AND TACHOMETER FEEDBACK TEST (continued)
6. Make the following voltage tests:
a. Turn the machine OFF between each test.
b. Carefully insert the meter probes into the
back of each Molex plug pin cavity to per-
form the test.
c. Turn the machine ON and pull the gun trig-
ger to conduct the voltage test.
FROM TO
LEAD LEAD
B W
(4J1) (2J1)
7. If the voltage to the wire drive motor armature is
zero, check the wires between plug J1 and the
wire drive motor. Also check the electrical con-
nector J12 for proper connection and contact.
8. If all wires and connectors are good and the
voltage to the drive motor armature is zero, the
control PC board may be faulty, replace the
control PC board.
9. If the motor is running at high speed and the
armature voltage is high and uncontrollable,
proceed with the tachometer test.
TROUBLESHOOTING AND REPAIR
WIRE DRIVE MOTOR
EXPECTED
VOLTAGE
3-20 VDC
(varies depend-
ing on wire feed
speed)
Power MIG® 255XT
TEST FOR SUPPLY VOLTAGE TO
TACHOMETER
1. Disconnect the main AC input power to the
machine.
2. Locate plug J1 on the control PC board. See
Figure F.9.
LEAD
515B
206B
3. Locate the following leads on Plug J1:
4. Connect main input power to the machine.
5. Make the following voltage tests:
a. Turn the machine OFF between each test.
b. Carefully insert the meter probes into the
back of each Molex plug pin cavity.
FROM TO
LEAD LEAD
515B 206B
(5J1) (1J1)
6. If the 15 VDC is present, check the leads to the
tachometer circuit.
7. If the leads are okay and 15 VDC is present, the
correct voltage is being received from the con-
trol PC board, continue with the Supply Voltage
to Tachometer Test.
8. If the 15 VDC is not present and the leads are
okay, the control PC board may be faulty,
replace the control PC board.
F-29
PLUG
LOCATION
5J1
1J1
EXPECTED
VOLTAGE
15 VDC