Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 80

F-28
G2081-[ ]
PROCEDURE
1. Remove input power to the machine.
2. With the 5/16" nutdriver, remove the screws and
carefully lower the front control panel.
3. On the power board, locate the test points that
are called out in the following Power Board
Voltage Test Chart. See Figure F.4.
4. Connect the volt/ohmmeter to each set of test
points and compare your reading to the expect-
ed reading from the chart.
WARNING
ELECTRIC SHOCK can kill.
• With input power ON, there
are high voltages inside the
machine. Do not reach into
the machine or touch any
internal part of the machine
while power is on.
TROUBLESHOOTING AND REPAIR
POWER BOARD TEST (continued)
FIGURE F.4 – POWER BOARD TEST POINTS
SQUARE WAVE TIG 355
12 11 10 9 8 7
J4
6 5 4 3 2 1
• Apply power and press the start button.
• If the correct voltages are being applied to
the power board but NOT generated by the
power board, the power board may be faulty.
• If the background voltages are NOT being
applied to the power board, the control trans-
former, the background rectifier, or the asso-
ciated wiring may be faulty.
5. After the tests are completed and the problems
repaired, install the front control panel, using
the 5/16" nutdriver.
F-28
10 9 8 7 6
J2
5 4 3 2 1
SQUARE WAVE POWER