Section
V
Paragraphs 5-1 to 5-7
Model 204B
5-1.
INTR U
I
SECTION
V
MAINTENANCE
N.
5-2.
This section provides maintenance and service
information for the Model 204B Oscillator. Required
test equipment, replacement and adjustment proce-
dures, and
a
troubleshooting summary
are
included
in the section. Also includedare performance checks
which verify proper instrument operation,
5-3.
REQUIRED
TEST
EQUIPMENT.
5-4. Test equipment required for maintaining and
checking performance of the Model 204B
is
listed
in
table 5-1. Equipment having similar characteristics
can be substituted for the equipment listed.
5-5.
PERFORMANCE CHECKS.
5-6. The performance checks verify that the Model
204B
is
operating normally and
is
accurately cali-
brated. These checks may be used
after
maintenance
or
as
part of incoming quality control inspection. In
the following checks be sure the test equipment used
has been recently calibrated.
5-7. DIAL ACCURACY CHECK.
a.
Connect frequency counter and 600-ohm load to
oscillator output
as
shown in figure 5-1.
b. Set Model 204B controls
as
follows:
RANGE.,
.............
XI
FREQ..
...............
5
AMPLITUDE.
.........
MAX.
VERNIER
..........
centered
Instrument Type
Oscilloscope
Distortion Analyzer
AC Voltmeter
DC Voltmeter
Clip-On
Milliammeter
Frequency Counter
01369-3
5232A/ S32A
FOR DIAL ACCURACY
@
2040
I
I
I
I
0330
C/D
I
-6OOn
Figure 5-1. Test Setup for Dial Accuracy
or
Distortion Checks
c. Set frequency counter controls
as
follows:
Function.
,
100
PERIODS AVERAGED
SENSITIVITY,
............
3
DISPLAY. maximum counterclockwise
d. Counter should read 200 i6 milliseconds.
e.
Set FREQ. dial to 20, counter should read 50.0
i1.5 milliseconds.
Table 5-1. Required Test Equipment
Required Characteristics
Passband: dc to 600 kc
Sensitivity:
0.1
volts/cm
Input Impedance:
1
megohm
Measure distortion to -40 db
Frequency Range: 5 cps to
Voltage Range:
1
mv to 5 volts
Accuracy:
*l%
Voltage Range: Positive and
1
kc
600 kc
negative voltages from 100
m
to 15 volts
Input impedance: at least 10
megohms
Range: 5 to
11
milliamperes
Accuracy:
*3%
Counting Range: 5 cps to
600
kc
Accuracy: 0.03%
Us
e
Waveform checking
Distortion measurement
AC voltage measurements
DC voltage measurements
Charge current
Frequency measurements
measurements
Recommended Model
@
Model 175A with
plug-in Model 1753A
@
Model 330B/C/D
@,I
Model 400H
@
Model 412A
@
Model 428A
@
Model 5232A/5532A
5-1