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CHAPTER 7: MAINTENANCE
875DP/500DP/500HV DUAL PULSE
RESISTANCE WELDING
POWER SUPPLIES
7-8
990-290
Calibration
The power supply should not require any regular adjustments. Use the following procedure as a
guideline to
check
the calibration. Take care not to make unnecessary adjustments; however, if any
components or software are replaced, check the calibration. Do not hesitate to call the Miyachi America
Repair Department with any questions.
Calibration should be performed only by a qualified technician. Test equipment should be calibrated for
accuracy.
Test Equipment Required.
a Oscilloscope
b Digital Voltmeter, Keithley 2002 or equivalent
Pre-Calibration Procedures.
Calibration is performed using the instructions displayed on the
screen and the HELP messages. The procedure consists of verifying power supply voltages and
capacitor bank values, and adjusting five trimpots on the control printed circuit board. As each
trimpot
adjustment is performed, it must be displayed on the screen with the cursor positioned
next to the instruction.
NOTE:
It is not necessary to turn the trimpots if you are only performing a calibration check.
NOTE:
500/875DP power should be ON for at least 5 minutes before attempting calibration.
1 Switch power OFF.
2 Remove the cover.
CAUTION:
Exercise static protection procedures so that no IC chips are damaged.
3 Switch power ON. Use a DVM to check the voltage at each of the points listed in table 7-1. Use
TP0 as reference ground.