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TROUBLESHOOTING AND REPAIR
SHUNT CALIBRATION TEST (continued)
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TEST PROCEDURE
NOTE: In this test procedure, the positive output stud is used for common.
1.Using the 5/16” nut driver, open the control panel and tilt out. Remove the control board cover. Start the machine.
WARNING
There are high voltages present inside the control box while the machine is running. THE VOLTAGES ARE HIGH ENOUGH TO KILL. Use extreme caution to avoid the back- side of the receptacles, breakers, and
terminal strip while checking voltages inside the control box.
2.Set the range switch to the CC/General fabrica- tion tap. Using the fine control pot, set the pre- set amps on the display to 300 amps.
3.Using a grid bank, load the machine to 300 amps at 25 volts using an external ammeter and volt- meter.
4.At the control board, measure the voltage from J1 pin 3 (pos. lead) to J1 pin 2 (neg. lead). See Figure F.29. The voltage should be 25 mVDC +/- 5%. The current reading on the display should be within +/- 5% with the external ammeter. See Figure F.29.
5.If step 4 fails, the shunt is out of calibration and must be replaced.
6.If the test is complete, replace the control board cover and close the control panel.
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Figure F.29 Control Board Plug J1
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| C112 |
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|
|
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| J20 | J22 |
J2 |
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| J1 |
J6 | J5 | J8 | J7 | |
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| J4 |
Plug J1
+Pin #3
