TM 9-6625-1753-14
C2
Table 2-5. Dual race Plug-In 79-02A, Check Procedures (Nonperiodic)
Table 2-5. Dual Trace Plug-in 79-02A. Check Procedures (Nonperiodic)
Step
Operation
Normal Indication
Corrective procedure
Step
Operation
Normal Indication
Corrective procedure
d. While watching the CRT trace, rotate the CH1 VARIABLE control throughout its range.
1.
Establish the check condition.
Vertical movement of the trace is less than -1/16 inch.
b. Set the CH1 and CH2 controls as follows:
Repeat b(1) through b(8) above, sub-
stituting 1 for 2 wherever it appears in
VOLTS/DIV ....................................................... 0.1
channel and control designators.
VARIABLE ............................... CAL , X1 (pushed in)
4.
Check chopped operation.
NORM-INVERT ............................................NORM
a. Set the chop rate switch to 100 KC.
b. Set the MODE switch to CHOP, and the TIME/DIV switch (delayed sweep plug-in unit) to 5 sec. Adjust the
2.
Check adjustment of the gas compensation resistors.
POSITION controls so that the trace appears as a broken line.
a. While observing the trace, set the DC-AC-GND switch for CH1 to GND, to AC, and again to GND.
The width of each dark space (blanked area) between segments of the trace does not
There is no visible movement of the trace on the CRT.
exceed 3 divisions on the CRT overlay.
Adjust the GAS COMP 1 resistor.
The switching transients (bumps or dips in the trace at the start or end of a trace
b. Set the MODE selector switch to CH2. While observing the trace, set the DC-AC-GND switch for CH2 to GND, to
segment) are blanked.
AC, and again to GND.
Refer to figure 4-4.1.
There is no visible movement of the trace on the CRT.
c. Set the chop rate switch to 1 MC and the TIME/DIV switch to 0.5 sec. The width of each dark space (blanked
Adjust the GAS COMP 2 resistor.
area) does not exceed 3 divisions on the CRT overlay. The switching transients are blanked.
3.
Check adjustment of the DC balance controls.
Refer to figure 4-4.1.
a. Adjust the CH2 POSITION control to position the trace behind the cent er grid line. While watching the trace,
5.
Check amplifier balance.
rotate the CH2 VARIABLE control throughout its range.
a. Set the controls as follows:
Vertical movement of the trace is less than 1/16 inch.
Dual trace plug-in 79-02A
(1) Adjust the CH2 DC BAL control.
DC-AC-GNC (CH1)..................................................... GND
Repeat a and b above.
MODE switch............................................................... CH1
(2) Set the CH2 GAIN ADJ control
VOLTS/DIV (CH1).......................................................... 0.1
fully clockwise and set the DC BAL
VARIABLE (CH1) ................................ CAL, X1 (Pushed in)
control to the center of its range.
Delaying sweep plug-in
(3) Readjust the CH2 POSITION con-
TIME/DIV ..............................................................0.5 sec.
trol as necessary to center the trace.
(4) While rotating the CH2 VARIA-
b. Switch the CH1 NORM-INVERT switch to INVERT, and then to NORM.
BLE control through its range, adjust
There is no visible movement of the CRT.
the DC BAL 2 control to minimize shift-
(1) Adjust the INV BAL 1 control.
ing of the trace.
(2) Repeat b to check the adjustment.
(5) Set the CH2 VOLTS/DIV switch
(3) Refer to figure 4-4.1.
to CAL.
c. Set the MODE switch to CH2, and repeat b above, using the CH2 NORM-INVERT switch and the INV BAL 2
(6) Adjust the CH2 DIODE LEVEL
control.
control for a maximum amplitude wave-
shape.
(7) Reset the VOLTS/DIV switch to
0.1.
(8) While rotat ing the CH2 VARIA-
BLE control throughout its range, ad-
just the DC BAL 2 control to minimize
shifting of the trace.
(9) Repeat a and b above.
c. Set the MODE switch to CH1, and adjust the CH1 POSITION control to position the trace behind the center grid
line.
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