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Maintenance
Refer to Appendix A for complete maintenance
information.
I f trouble exists in the output amplifier, remove the +
and - tracking power supply jumpers located as shown in
the adjustment location illustration. This completely
isolates the tracking power supplies from the output
circuitry.
Circuit Board removal
To remove the output circuit board and gain access to
the components on the variable transition timing board,
first remove the four screws on the plug-in rear panel
and remove the panel. Next remove the TRANSITION
TIME knob. Disconnect the coaxial cable plugs and
unplug all the wires connected to the output and
transition time boards. Finally, remove the four screws
holding the output board to the plug-in frame and
remove the two boards by sliding toward the rear of the
plug-in until the TRANSITION TIME shaft clears the
front panel hole. Now lift the boards and remove them
from the mainframe. To remove the input board remove
the wires and cables to the input board and the two
screws holding the board chassis. To remove the timing
board, first remove the rear panel, as explained above.
Then remove the PERIOD, DELAY, and DURATION
knobs from their shafts. Disconnect all wires and cables
leading to the timing board. Remove the four screws
holding the timing board to the spacers. Slide the timing
board toward the rear of the plug-in until the shafts clear
the front panel and lift the board out.
GENERAL MAINTENANCE AND ADJUSTMENTS
Test Equipment
For adjustment of the PG 508, the following
equipment is recommended:
Complete oscilloscope system, capable of faithful
reproduction to at least 500 MHz. TEKTRONIX 5440
mainframe, 5A45 real time vertical amplifier, and 5B42
real time delaying sweep plug-in suggested.
50 Ω 42 inch coaxial cable with bnc connectors,
Tektronix Part No. 012-0057-01, or equivalent.
General
Adjustments for the PG 508 are described below. For
complete calibration procedures, refer to TB 11-6625
2980-35.
Output Voltage Control Knob Check or Adjustment
To check or reset the OUTPUT (VOLTS) control
knobs, use the following procedure. Connect an
oscilloscope to the PG 508 OUTPUT connector. Set the
DURATION control to the SQ WAVE position, and the
PERIOD control at the 2 ms position. Set the HIGH
LEVEL knob for an output level of about +5 V on the
oscilloscope, and the LOW LEVEL for 0 V. If the LOW
LEVEL knob does not point to 0, loosen the set screw
and reset the knob to the 0 mark on the front panel. Now
set the LOW LEVEL knob for a reading of about -5 V,
and the HIGH LEVEL for 0 V on the oscilloscope. If the
HIGH LEVEL knob does not point to 0, loosen the
setscrew and readjust.
3-2
TM 11-6625-2980-14
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