Test Procedures - Lincoln Electric PRECISION TIG 375 Service Manual

F-28
T1 MAIN TRANSFORMER TEST (continued)
G3909

TEST PROCEDURES

1. Using the 3/8" nut driver, remove the two screws
from the front control panel. Carefully lower the
panel. This will allow access to the control board.
2. Locate plug J11 on the control board. See Figure
F.5.
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.
3. Carefully apply the correct input power making cer-
tain the reconnect configuration at the reconnect
panel is correct for the input voltage applied. Turn
the Precision TIG 375 ON.
4. Using the voltmeter, carefully test for the correct
transformer secondary voltages per Table F.3.
TROUBLESHOOTING & REPAIR
Figure F.5 - Plug J11
PRECISION TIG 375
263
214
204
Plug
210
J11
209
201
265
262
5. Carefully check for 63.5 VAC at leads 267 to lead
268. Lead 268 is located at the background rectifier.
Note: Lead 267 is located at resistor R8. See Wiring
Diagram.
6. Carefully check for 115 VAC at leads 231 to 232.
Note: Lead 231 is located at the 115 VAC receptacle
on the back of the machine. Lead 232 is located
at the 15 amp circuit breaker CB1.
7. If all of the secondary voltages are correct, the T1
transformer is functioning properly.
a. If all of the secondary voltages are missing or
incorrect, make certain that the correct input
voltage is being applied to the correct primary
leads. See Table F.3.
b. If the correct input voltage is being applied to the
primary leads and any or all of the secondary
voltages are incorrect, the T1 transformer may
be faulty. Also check the leads for broken or
loose connections between plug J11 and the T1
transformer.
8. Replace the case side covers
F-28
266
220
270
253
Plug
J11
252
269
271
213