4. CHECK CALIBRATOR AMPLITUDE
a. Remove Q2114 located on Sweep board near Cali
brator output.
b. Using DVM measure voltage at CAL 5 V output on
front panel. Record the voltage.
c. Remove Q2124.
d. Check that CAL 5 V output is 5 V more positive
(±5 mV) than the voltage recorded in step b.
e. If necessary adjust CAL 5 V (R2130).
f. Replace Q2114 and Q2124.
5. ADJUST CALIBRATOR FREQUENCY
a. Set TIME/DIV to 0.2 ms; INT TRIG to CH 1; VERT
MODE to ADD.
b. Apply 1 ms markers from the Time-Mark Generator
to CH 1 50 input; connect CAL 5 V, FREQ 1 kHz to
CH 2.
c. Set VOLTS/DIV to obtain about 2 div of signal.
d. Trigger display (markers).
e. Adjust 1 kHz (R2105) for less than 0.5 cycles
(2.5 div) of square wave (calibrator) drift in 1 second.
(0.5 Hz/1 kHz = 0.0005 or 0.05%).
f. Set TIME/DIV to 2 ms; INT TRIG to NORM;
coupling to DC; CAL 5 V frequency to 1 MHz; Time-Mark
Generator to 1 ps; VERT MODE to ADD.
g. Trigger at top of waveform from the CW end of
trigger LEVEL. Use A TRIGGER HOLDOFF to obtain
display showing the beat frequency.
h. Adjust 1 MHz (R2100) for beat period greater than
2 ms. (0.5 kHz/1 MHz = 0.0005 or 0.05%.)
Calibration—485/R485 Service
6. CHECK CALIBRATOR 1 kHz DUTY CYCLE
(49.8 to 50.2%)
a. Connect 1 kHz of CAL 5 V to CH 1 input; CH 1
impedance to 50 El; CH 1 VOLTS/DIV to 0.1 V; INT TRIG
to NORM; A TIME/DIV to 0.1 ms; B TIME/DIV to 1 ps;
HORIZ DISPLAY to INTEN; B TRIGGER SOURCE to B
RUNS AFTER DELAY TIME.
b. Trigger A on + SLOPE; use DELAY TIME POSITION
control to position the intensified portion of the negative
step near center screen.
c. Switch HORIZ DISPLAY to B and position the
negative step to center screen.
d. Switch A SLOPE polarity and check that the
transition changes less than 3 divisions horizontally.
7. CHECK CATHODE REGULATOR +95 V
(± 8 V )
a. Set INTENSITY controls CCW.
b. Measure at CATH REG test point on rear of
Horizontal Amp board.
c. If necessary adjust R1625 located next to CATH
REG test point.
8. CHECK -3 0 0 0 V for ±50 V; or ±500 V With
VOM Accurate to 2% (this voltage is marked
—2950 in some instruments)
a. Make this measurement using the precision divider in
conjunction with the precision DC voltmeter, or use high
voltage scale of 2% VOM.
b. Measure through hole in plastic cover at rear of
Horizontal Amp board.
c. This voltage should be within the —2950 to —3050 V
range because of correct adjustments performed in steps 1,
2, and 7.
9. CHECK COMPENSATION PLATE VOLTAGE
NOTE
Adjustments and test points are accessible from the
top of the instrument.
REV. E, MAR. 1978
5-9
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