Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 88

F-36
PILOT TRANSFORMER TEST (continued)
PROCEDURE
1. Remove input power to the machine.
2. With the 5/16" nutdriver, remove the machine
top and sides.
3. Locate terminals X1 and X2 connected to the
pilot transformer secondary. See Figure F.7.
4. Connect the volt/ohmmeter to X1 and X2.
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.
5. Turn on input power to the machine.
TROUBLESHOOTING AND REPAIR
FIGURE F.7 – PILOT TRANSFORMER CONNECTIONS
SQUARE WAVE TIG 355
X1
X2
6. Check for 120 VAC at the X1 and X2 terminals.
• If 120 VAC is present at X1 and X2, the pilot
transformer is good.
• If 120 VAC is NOT present at X1 and X2, check
for the correct primary voltage at leads H1 to HX,
depending on the input voltage being applied to
the machine. See the machine Wiring Diagram.
NOTE: H1 is located at L1 on the input side of CR1
input contactor.
If the correct voltage is being applied to the prima-
ry of the pilot transformer and 120 VAC is not pre-
sent at terminals X1 and X2 of the secondary wind-
ing, the pilot transformer may be faulty. Replace.
NOTE: The secondary voltage will vary with fluctu-
ations in the input line voltage.
7. After the tests are completed and the problem
repaired, install the machine sides and top,
using the 5/16" nutdriver.
F-36