Emerson Keystone Figure 637, Service Manual

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Emerson Radio
Model 648B
1. GENERAL
Model 648B is a wide-band video receiver,
providing direct view high-definition pictures on
a ten-inch electro-magnetic deflection kinescope.
This model incorporates several design features
including Expan-Scope, Built-In-Antenna, Auto­
matic Gain Control, Inter-carrier Sound, Auto­
matic Frequency Control and a Transformer
Power Supply.
Model 648B uses chassis 120110E and is
housed in a plastic cabinet.
It should be noted that the tuner assembly
part number listed for chassis 120110E is not
the same as the tuner part number listed for
chassis 120110B. These tuners are identical elec­
trically, the only variation being mechanical.
Alignment procedure, circuit description and
general information, will be the same as that
given for Model 614 using chassis 120110B.
2. EXPAN-SCOPE
The Expan-Scope incorporates a remote switch with a 20 foot extension cord which enables the viewer to either
watch a normal picture or one which is expanded both vertically and horizontally so that the center of the picture is
enlarged. This unit is plugged into the expan-scope jack in the rear of the chassis. (See Fig. 1)
The horizontal expansion is accomplished by inserting condenser (C-78) in series with the horizontal deflection
yoke and opening the horizontal width coil (L-6). The vertical expansion is accomplished by raising the plate voltage
of the vertical amplifier. This is done by shorting resistor (R-105). To improve vertical linearity (R-102) is also shorted.
CABINET PARTS LIST— (MODEL 648B)
PART NO.
140335
410805
450041S
450044
450045
45005 IS
505040
520103
5601UB
580689
583206
^85056
635023
180066
DESCRIPTION
Cabinet— Bakelite
Mask
Knob— Off-Volume
Knob-— Fine Tuning
Knob— Contrast and Brightness
Knob— Selector
Connector Plug— Speaker
Selector Escutcheon
Back
Twin Conductor Lead (1 1 0 ")
Line Cord
Plug and Cable— (Speaker)
Safety Glass
Speaker— ( 6 ")
TUBE COMPLEMENTS—(CHASSIS 120110-E)
SYMBOL
TUBE
TYPE
FUNCTION
V I 6AG5
First video i-f amplifier
V2 6AG5
Second video i-f amplifier
V3
6AU6
Third video i-f amplifier
V4 6AL5
Video detector and AGC
V5
6AU6 First video amplifier
V 6 12AU7
Second video amplifier; second
sync amplifier
V7 6AU6
Sound i-f amplifier
V8
6AU6
Sound limiter
V9
6T8
Sound disc, and audio amp.
V10 6V6GT
Audio output
V l l
6SN7GT
Hor. phase invert.; horizontal
control,Cd.c. amp.)
V 12
6AL5
Hor. phase det. (sync disc.)
V 13
6SN7GT
Hor. oscillator and discharge
V 14 6SN7GT
Vert, oscillator and discharge
V 15 12AU7
Sync sep. and d.c. restorer;
first sync amplifier
V l6
6K6GT
Vertical output
V 17
6BG6G
Horizontal output
V 18
1B3GT
High-voltage rectifier
V19
6W 4G T
Horizontal damper
V25 10BP4
Kinescope
V27
6J6
Oscillator ?md converter
V28 6 AG 5
R-f amplifier
V29
5U4G
Low-voltage rectifier
Fig. 1 —Operating Controls
PARTS LIST
SYMBOL PART NO. DESCRIPTION
C-5 928006 1,500 mmf Ceramic, 400v
C-6 928006 1,500 mmf Ceramic, 400v
C-7 928109
.005 mf Circ. Ceramic, 400v
C-8
928006 1,500 mmf Ceramic, 400v
C-9
910015 270 mmf Mica, 400v
C-10
928006 1,500 mmf Ceramic, 400v
C -ll
928006 1,500 mmf Ceramic, 400v
C-12 910015 270 mmf Mica, 400v
C-13
928006 1,500 mmf Ceramic, 400v
C-14 928006 1,500 mmf Ceramic, 400v
C-15 910290 30 mmf Mica, ± 10%
C-16 923062 .05 mf Paper, 400v
C-17 928006 1,500 mmf Ceramic, 400v
C-18 922025
.047 mf Paper molded,
± 2 0 % , 400v
C-19
922025 .047 mf Paper molded,
± 2 0 % , 400v
C-20
922008 .1 mf Paper molded,
± 2 0 % , 400v
C-21 Pt. of C-39 10 mf Electrolytic, 450v
C-22 922015 .01 mf Paper molded,
± 2 0 % , 400v
(Continued, on page 2 7 )
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