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If the r e s i s t a n c e s are within tolerance and the
dials operate properly, disconnect the r e s i s t a n c e bridge
and proceed t o paragraph 6.6.6.
CGRL justifying mechanism. If the readings are
SENS
abnormal, the CGRL rheostat mechanical justifying
mechanism must be readjusted.
T h e CGRL rheostat
1650.9
mechanical justifying mechanismconsists of eight cam
Figure
6
-
3.
Schematic for checking the detector circuit.
screws located on the rear of the CGRL rheostat
(Figure 6-Z), numbered from 1 t o 8 in a clockwise
direction a s indicated in the figure.
T o adjust, s e t
t o Table 6-8).
Check the battery voltage with the
them
for
the proper resistances
a s indicated in Table
panel
meter
(BAT CHECK position)
before reading
6-6.
transistor voltages.
Vernier drive.
The CGRL d i a l h a s a vernier
planetary drive with a 7:l reduction over a 90-degree
6.6.7 DETECTOR.
knob rotation.
It c o n s i s t s of two solid g e a r s and one
spring gear in a triangular configuration centered in a
combination of three outside rings (gear, cork, and
solid metal). When a c o a r s e setting i s made, the cork
ring s l i d e s inside the metal ring. When the vernier i s
used, the cork ring i s similar t o an engaged clutch and
s t o p s the rotation of the outside rings, leaving the
internal reduction g e a r s t o rotate.
It will not be nec-
e s s a r y t o disassemble t h e s e g e a r s in any of the service
procedures described in t h i s instruction manual.
6.6.6 OSCILLATOR.
Set the function switch t o AC INTERNAL 1 kHz
and the OSC L E V E L control t o i t s full cw position.
Use the C, bridge with nothing connected t o the
UNKNOWN terminals.
The CGRL control should be
full cw.
Perform the c h e c k s listed in Table
6-7
by
measurement of the output of the oscillator between
the collector of 4 1 0 3 and ground.
If operation is found t o be abnormal, perform a
stage-by-stage voltage c h e c k of the transistors (refer
T o c h e c k t h e detector, s e t the controls a s follows:
PARAMETER
s
GENERATOR
A C E X T E R N A L
CGRL
F u l l c c w
DQ
F u l l c c w
MULTIPLIER
100 p F
D E T SENS
F u l l c w
Continue with the following procedure:
a. Connect
a
100-kR resistor
between
t h e
UNKNOWN terminals.
b. Short out the EXT GEN terminals with a
shorting plug. The null meter should d&flect l e s s than
%
division due t o noise. Remove t h e shorting plug.
c. Connect an external oscillator ( 1 kHz) t o the
E X T GEN jack.
Turn the CGRL control full cw. T h i s
s e t s up the circuit of Figure 6-3.
d. Use a 1-KHz external oscillator and adjust
the external oscillator's level control s o there is
3
V
TABLE 6-7
OSCILLATOR PERFORMANCE CHECK
"Measurement Conditions: DET SENS full ccw, OSC LEVEL
full cw, GENERATOR switch at AC INTERNAL I kHz;
measurements made with GR Type 1806 ELECTRONIC
VOLTMETER between component and ground; all voltages
are positive. Voltages may vary
f
10%.
MEASUREMENT
Frequency:
1000 Hz, *20 Hz
Output voltage:
at least 2.7 volts rms
Distortion:
less than 2.5%
I H B L t 0-8
N O M I N A L TRANSISTOR VOLTAGES*
S E R V I C E A N D M A I N T E N A N C E
6-7
REMARKS
If frequency is incorrect, check
thevaluesof R101, R102, R103,
C102 and C103.
Measure with OSC LEVEL fully
clockwise.
Low output or excessive distortion
may be due to weak batteries (refer
to paragraph 6.5.1
).
If the batteries
are normal, R 107 or R 108 may be
clipped out to increase the OSC
LEVEL slightly.
TRANSISTOR
-
0 1 51
6 1 52
0 1 53
0154
Q101
Q102
0 1 03
COLLECTOR
(VOLTS)
4.6
0.52
5.0
2.7
0.6
3.3
0.13
BASE
(VOLTS)
2.2
0.52
0.52
5.2
4.3
0.6
4.6
EMITTER
(VOLTS)
1.6
0.0
0.0
5.9
5.0
0.0
5.4
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