SECTION 3. CALIBRATION AND TEST OF PC CONTROL BOARD
1. General
This section describes the test points, test values, and adjustment locations for testing and adjusting
the printed circuit control board which is the “brains” of the GPU-600 DC power supply. As a minimum
the following equipment and tools are required.
A. High impedance, high accuracy DC voltmeter;
B. Small, standard blade screwdriver;
C. Small, insulated clip leads;
D. A resistance load bank or equivalent that can safely dissipate 2200 ADC at 20-V DC if the
overcurrent trip point is to be checked or adjusted.
Faulty control boards should be returned to the manufacturer for repair.
2. Printed Circuit Board Test Values and Adjustments
A. Refer to Figure 1 for the location of test points and adjustment potentiometers for possible field
adjustment.
B. Test point values and comments about the measurements and testing conditions are tabulated
in Figure 2.
WARNING: ELECTRIC SHOCK AND ARCS CAN KILL OR INJURE! USE ACCESS DOORS TO IN-
SPECT, OR TEST THE PRINTED CIRCUIT CONTROL BOARD WHILE THE EQUIPMENT IS RUNNING.
THE VOLTAGES ON THE PRINTED CIRCUIT BOARD ARE SAFE; HOWEVER, REMOVING THE RIGHT
SIDE PANEL EXPOSES PEOPLE TO DANGEROUS VOLTAGES.
C. Test and Calibration Procedure
Follow Figures 1 and 2 to verify that the PC board is functioning to the standard. If the voltage
readings to the PC board common are not within specification, attempt to correct the reading by
adjusting the applicable control. Be certain the operating conditions are exactly as stated in Fig-
ure 2. If the board does not adjust and the leads, fuses
(F2-F7)
, and connectors to the PC control
board are good and proper, the PC control board is faulty. Replace it with a known good board af-
ter the input power has been turned off. The PC board is held in place by six
(6)
self tapping
screws. After unplugging the three polarized connection plugs, remove the screws and keep for
the new board. Reverse the procedure when the new PC board is mounted in the exact orienta-
tion of the old board. Recheck the voltages. In some cases a minor adjustment may be required
for optimum calibration. If the same magnitude of error and lack of adjustment control is encoun-
tered, it is possible that the control board is not at fault.
Consideration should be given to returning the GPU-600 DC power supply to the factory or an
authorized repair facility if your recheck of the GPU-600 does not find the cause of the difficulty.
Field repair of the PC control board is not recommended.
OM-2010
April 10/89 Revised 3-3
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