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F-28F-28
PRECISION TIG 275
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TROUBLESHOOTING & REPAIR
T1 MAIN TRANSFORMER TEST (continued)
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.4.
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 275 ON.
4. Using the voltmeter, carefully test for the correct
transformer secondary voltages per Table F.3.
5. Carefully check for 63.5 VAC at leads 267 to lead
268. Lead 268 is located at the background rectifi-
er.
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 recepta-
cle 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 sec-
ondary voltages are incorrect, the T1 trans-
former 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.
Figure F.4 Plug J11
263
214
204
2
10
2
66
2
53
270
220
209
262
265
201
252
269
271
213
Plug
J11
G3909
P
lug
J11
WARNING