Emerson Radio
TUNER ALIGNMENT: (Table V I I ).
STEP
SIG N A L GENERATO R IN P U T
C H A N N E L
A D J U S T
PROCEDURE
SWEEP G EN.
M AR. G EN.
1
207.0 MC.
209.75 MC.
12
A 12
Adjust for placement of 21.25 MC. marker
as per overall response curve.
2
»
12
A 14,
A 15,
A 16
Adjust shape of overall response curve for
maximum amplitude and bandwidth.
3
213.0 MC.
215.75 MC.
13
A13
Adjust as in Step 1.
4
201.0 MC.
203.75 MC.
11
A l l
»
5
195.0 MC.
197.75 MC.
10
A 10
»
6
189.0 MC.
191.75 MC.
9
A 9
7
183.0 MC.
185.75 MC.
8
A 8
8
177.0 MC.
179.75 MC.
7
A 7
»
9
85.0 MC.
87.75 MC.
6
A 6
99
10
79.0 MC.
81.75 MC.
5
A 5
99
11
69.0 MC.
71.75 MC.
4
A 4
99
12
63.0 MC.
65.75 MC.
3
A3
99
13
57.0 MC.
59.75 MC.
2
A 2
99
N O T E : The r-f response curve of the tuner, on each channel may be observed by connecting the scope in series with a 10K
resistor to the test point shown in figure 5-9. The curves should have maximum amplitude and flatness, consistent with
proper placement of the 21.25 me. marker on the i-f response curve.
8.
VOLTAGE AND RESISTANCE ANALYSIS—
Voltage and resistance readings are indicated in figure
5-10, to aid in servicing the chassis. The diagram indi
cates typical values obtained under the following con
ditions.
a.
A N A L Y S IS C O N D IT IO N S :
1) Line voltage maintained at 117 volts for volt
age readings.
2) Measurements made with voltohmyst or equiv
alent.
3) All voltage measurements are in + d.c. volts
and resistance in ohms, unless otherwise noted.
4) Socket connections are shown as bottom v:ews.
Measured values are from socket pin to B— ,
unless otherwise stated.
5) Readings made with antenna disconnected, no
signal applied and controls at normal.
6) Readings marked * are measured to ground.
9.
DEFLECTION CIRCUIT WAVE FORMS —
See figure 5-11. The sweep voltages produced in the
horizontal and vertical sweep circuits may be used in
locating defects in the deflection section of the chassis.
Two separate wave forms are shown" at various test
points up to the output of the second sync amplifier
(V 6 B ), as both horizontal and vertical pulses are pres
ent.
Different sweep frequencies are required at the
scope to distinguish between the sync pulses.
a.
A N A L Y S IS C O N D IT IO N S:
1) Line voltage maintained at 117 volts.
2) Controls at normal; no signal input.
3) Peak-to-peak values indicated may vary due
to component tolerances and response of scope.
Readings are obtained by calibration of scope,
prior to observation of waveforms.
Figure 5-9— Side View Tuner
10.
PRODUCTION CHANGES— Several changes
have been incorporated in the chassis used in Models
614, 637, and 644, during production. These changes
may be identified by code markings consisting of a tri
angle containing a particular number, stamped at the
rear of the chassis. Presence of a particular marking
indicates that the revisions described have been made
in the chassis. The various revisions are summarized
below. Unless otherwise noted, the changes have been
added to all subsequent models.
R -F AMP
' 6AQS
TEST POINT
ft-F OUTPUT, CONV.
AND OSC. COILS
(L-3,L-4 ,L -5 *
R-F INPUT
COILS
CL-l»L-2)
17
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Summary of Contents for Keystone Figure 637
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Page 14: ...Emerson Radio iOUNO D ISC itic Jbiagram Chassis 120110B 14 Scanned by mbear2k Jan 20121 17 ...
Page 26: ...Emerson Radio dio M 26 28 Scanned by mbear2k Jan 20121 17 ...
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