Model 140A Section V
Paragraphs 5-1 to 5-13
SECTION V
MAINTENANCE
5-1. INTRODUCTION. e. Deflection should be 10 cm *O.l cm.
5- 2. This section covers maintenance, trouble- f. Repeat steps a through e, using 0.5 V/CM
shooting, and adjustment of the Model 140A Oscil- vertical SENSITIVITY and 10 volts from the Volt-
loscope. A performance check is included which may meter Calibrator.
be used at incoming inspection or after adjustments
have been made to verify that the instrument meets
its specifications. 5-6. ADJUSTMENTS.
5-7. The following paragraphs (5-11 through 5-17)
give a complete adjustment procedure for the Model
5-3. PERFORMANCE CHECK.
140A Oscilloscope. A condensed procedure is given
5-4. CRT CONTROLS. in Table 5-3. If difficulty is encountered in making
any adjustment, refer to Paragraph 5-18 for trouble-
a. Install a single large plug-in or two small plug-
s hooting procedures.
in units in the Model 140A (vertical plug-in in the
lower compartment, horizontal in the upper com-
5-8. EQUIPMENT NEEDED FOR ADJUSTMENTS.
partment).
Test equipment recommended for the adjustment
b. Set: POWER ................ ON procedure is listed in Table 5-1. Similar instruments
AMPLIFIER coupling (if present) . AC having the listed characteristics may be substituted.
POSITION controls ....... Centered
5-9. LOCATION OF ADJUSTMENTS. Figure 5-2
c. If a time base plug-in is being used, shows the location of all internal adjustments in the
Model 140A.
set: SWEEP TIME. ....... 1 MSEC/CM
TRIGGER SOURCE ......... +INT
5- 10. PRELIMINARY PROCEDURE. Plug-ins must
LEVEL ............ FREE RUN
be ! installed in both compartments whenever power
NORMAL/SINGLE ........ NORMAL
su ipply voltage measurements are made; proper
re gulation may not occur if insufficient loading is
d. A trace should be on screen. If necessary, turn
INTENSITY control clockwise. Pr .ovided. Set line voltage to 115 volts (230 volts if
th e 115/230 volt switch is in the 230-volt position).
e. Remove trace from screen with POSITION
controls. Depress BEAM FINDER. The trace
should appear on screen. 5-11. ADJUSTMENT OF LOW-VOLTAGE POWER
SUPPLIES.
f. The INTENSITY control shouldvary the intensity
of the display from extinguished to brighter than 5-12. Measure the output of each low-voltage supply,
normal intensity. and adjust it to the value shown in Table 5-2. Meas-
urement may be made on any wire bearing the indi-
g. The FOCUS and ASTIGMATISM controls should
cated color code.
defocus the display at the extreme of each control,
and focus the display at approximately midrange.
Adjust FOCUS and ASTIGMATISM for sharpest overall Table 5-2. Low-Voltage Adjustments
display.
I I I 1
h. Adjust TRACE ALIGN to set the trace parallel I Wire Color Code I Adjustment
to the horizontal graticule lines. If the horizontal I (Volts) I
plug-in is not a time base, connect the calibrator
signal to the horizontal amplifier input to produce a
- 100 Violet -lOOV Adj. R200B
straight-line trace.
-12.6 White/Violet -12.6V Adj. R200C
+loo White/Red +1OOV Adj. R200A
5-5. CALIBRATOR.
a. Set: Vertical SENSITIVITY .... 0.05 V/CM
INPUT coupling ............ DC
5-13. ADJUSTMENT OF HIGH-VOLTAGE SUPPLY.
b. Connect 1 VOLT PTP from the Voltmeter Cali-
brator to vertical INPUT. a. Connect a Model 11044A 1OO:l Voltage Divider
to the DC probe of a Model 410B VO!+-~+-
c. Adjust vertical VERNIER for exactly 10 cm
,) deflection. b. Set Voltmeter to 3-volt -DC ra
d. Disconnect the Voltmeter Calibrator and connect c. Set the Voltmeter Calibrator 1
the 1V CALIBRATOR output to the vertical INPUT. output, and connect divider tip to the
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