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E8


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                                                 PSSG
   PHILIPS SERVICE SOLUTIONS GROUP



                                     PHILIPS TECHNICAL
                                              TRAINING


                                                   E8
                                               COLOR TV
                                                CHASSIS



P H I L I P S               Philips Technical Training (USA)
                            401 E. Old Andrew Johnson hwy

TECH
                 TRAINING




                            PO box 555
                            Jefferson City, TN 37760
VIDEOT A P E S              PH: 865-475-0397
                            FAX: 865-475-0221
MANUALS
                            EMAIL: [email protected]
E8 OVERALL BLOCK FIGURE 1            The Mono version has a 1 watt
                                     audio amplifier. The Normal
                                     Stereo version has a 2x1 watt
The E8 series chassis is the         amplifier. The DBX Stereo version
Small Screen TV chassis produced     has a 2x3 watt amplifier. Latin
by Philips Consumer Electronics      American versions of this chassis
Company for the 1999-2000 model      may have a 2 or 3 watt Mono
year. The E8 is used with 13,        amplifier.
19, and 20 inch CRT's. The E8
Tuning System features a 181         The E8 chassis features a
channel Tuning System with On-       Switching Mode Power Supply. A
Screen Display. The Tuning System    "HOT" ground reference is used in
uses two IC's mounted on the main    the primary side of the power
chassis. It consists of a            supply. "COLD" (signal)ground is
Microcomputer IC and Memory IC.      used from the secondary of the
The Microcomputer communicates       power supply and throughout the
with the Memory IC, the Customer     rest of the chassis. AN ISOLATION
Keyboard, the Remote Receiver, the   TRANSFORMER IS REQUIRED WHEN DOING
U/V Tuner, the TV Signal             SERVICE ON ANY CHASSIS.
Processor, the Stereo Decoder
(optional), and the Power On-Off     SIGNAL FLOW
circuitry. The Memory IC retains
the settings for favorite            The incoming TV RF signal is
stations, customer control           applied to the U/V Tuner via the
settings, feature settings, and      Antenna and RF input. The
factory setup data.                  45.75MHz IF signal is developed
                                     within the U/V Tuner, then
The chassis features a Very Large    amplified by an IF Preamplifier
Scale Integration (VLSI) IC for TV   located inside the Tuner. The
Signal Processing. This IC           amplified IF signal is sent from
performs Video IF, Sound IF,         Pins 10 and 11 of the U/V Tuner
AFT/AGC control, Horizontal Signal   to the SAW filter, 1003. The SAW
Processing, Vertical Signal          filter produces bandpass shaping
Processing, Horizontal/Vertical      for the IF signal before it is
Synchronization, Chroma/Luminance    applied to the TV Signal
Processing, and Video Switching      Processing Integrated Circuit,
between internal and external        7250, for processing. AFT voltage
inputs. On-Screen Graphics from      is developed within 7250. These
the Microcomputer are placed on      voltage values are then sent to
the main signal within the TV        the microcomputer via the I2C bus
Signal Processor. Automatic          for Tuner Oscillator frequency
Volume Level (AVL) from the          correction.
Microcomputer is sent to the TV
Signal Processor (Mono Sets) and     Sound IF signal processing for the
to the Stereo Module (DBX Stereo     E8 chassis is performed by
Sets via the I2C bus). AVL for       coupling the 4.5MHz Sound IF
Normal Stereo is switched by Pin     signal from 7250 Pin 6 through
9 of the Microcomputer, 7600.        transistor 7266 and a 4.5MHz band

                                                                PAGE 1
PAGE 2




         FIGURE 1 - E8 BLOCK
pass filter 1001 to Pin 1 of 7250.   between Pin 13, the External Video
In the Mono version, Baseband        source on Pin 17, or the External
Audio from Pin 15 of 7250 is         Two Video source on Pin 11. The
buffered by transistor 7951 before   selected Video is fed to an
being applied to Bass and Treble     internal Y/C separator inside
circuits. The outputs of the Base    7250. Luminance and Chromance is
and Treble circuits are applied to   fed to an internal SVHS switch
a 1 watt amplifier 7954 in the US    which selects between internal Y/C
version or a 2 or 3 watt amplifier   or external Y/C on Pins 11 and 10.
7953 in the Latin version. In sets   Internally selected "C" Chromance
equipped with a Stereo module,       is fed to an internal Demodulator
Baseband Audio from Pin 15 of 7250   which outputs R-Y and B-Y on Pins
is fed to the Stereo Decoder         30 and 29. Internally selected
module. The DBX Stereo Decoder       "L" Luminance is output on Pin 28.
module has internal/external         R-Y, B-Y, and "L" are fed to the
switching, AVL switching,            Matrix circuit on Pins 31, 32, and
volume control, and alignment        27.
settings via the I2C bus (SDA &
SCL). Internal/external switching,   Red, Green, and Blue On-Screen
AVL switching, and volume control    display signals from the
for the Normal Stereo module are     Microcomputer 7600 Pins 34, 33,
performed through individual         and 32 are fed to the Signal
control lines from the               Processor 7250 Pins 23, 24, and
Microcomputer. Audio Output          25. Fast Blanking from 7600 Pin 35
Amplifiers for both the DBX and      is fed to 7250 Pin 26.
Normal Stereo versions are located   Brightness, Picture, Sharpness,
on the Stereo module. AVL            Color, and Tint control voltages
switching for the Mono version is    are developed within 7250 from the
performed in 7250 via the I2C bus.   Tuning System Microcomputer 7600
Volume for the Mono set is           via the I2C bus. The Red, Green,
controlled in the Audio Output       and Blue signals developed by the
Amplifier 7954 or 7953 by a          signal processor, 7250, are output
control line from the                on Pins 21, 20, and 19 and applied
Microcomputer 7600 Pin 2. Volume     to the CRT board. On the CRT
for the Normal Stereo is             board, these signals are amplified
controlled in the Stereo Module by   before being applied to the CRT.
a control line from the
Microcomputer 7600 Pin 2. Volume     The White Balance controls for the
control for the DBX Stereo is        CRT set-up are controlled within
controlled in the Stereo Module by   7250 by the Microcomputer via the
the Microcomputer via the I2C bus.   I2C bus. Adjustments are
                                     performed with the set in the
Composite Video from Pin 6 of 7250   Service Test Mode. Always use the
is buffered by 7266 and sent to      procedures in the Service Manual
1200, a 4.5MHz trap, to remove any   for setting up the CRT circuits
sound. The Video is then applied     (White Balance). The White Balance
to Pin 13 of 7250. The               is set by adjusting the White Tone
Internal/External switch selects     adjustments in the Service Test

                                                                PAGE 3
Mode.                                Current, excessive High Voltage,
                                     or a Low +13 volt supply
Horizontal and Vertical signals      (VLOTAUX13V). The BCL_PROTN
are also developed within 7250.      circuit of the IFT monitors for
Adjustment for Horizontal and        excessive Beam Current. If the
Vertical Geometry are done with      BCL_PROTN line goes High,
the Remote Transmitter via the       transistor 7611 will turn On,
Service Test Mode. There is no       causing Pin 16 of 7600 to go Low,
adjustment for the Horizontal        turning the set Off. Transistors
Oscillator. The Horizontal circuit   7403 and 7404 monitor the
is a count down type of system       secondary of the IFT for excessive
that gets its base frequency from    voltage. If the output of the IFT
the 3.58MHz circuit.                 should go too high, the HEW_PROTN
                                     line will go High, causing Pin 50
When the set is turned On, the Low   of 7250 to go High. This will
on Pin 19 of 7600 is removed         shut the Horizontal Oscillator
allowing the On/Standby line to go   Off. Transistor 7621 and Zener
High. The High is applied to         Diode 6612 monitors the 13 volt
7607, the Astable Multivibrator,     (VLOTAUX13V) line. If the 13 volt
which is powered by the +5VD         supply should go Low or fail, 7621
supply. The Astable Multivibrator    will turn On, causing Pin 16 of
7607 provides Horizontal Drive to    7600 to go Low, turning the set
drivers 7608 and 7400. The drive     Off. Transistor 7620 provides a
is then applied to 7402, the         power On delay for this circuit.
Horizontal Output transistor,
which drives the Horizontal          E8 CHASSIS POWER SUPPLY BLOCK
Deflection Yoke and the IFT. The     (Figure 2)
IFT develops high voltage, focus
voltage, and filament voltage for    When a 120Vac source is connected
the CRT. Scan derived voltages       to the E8 chassis, approximately
produced by the IFT are 160 volts,   160Vdc is developed by the bridge
VLOTAUX13V 13 volts, -13 volts,      rectifier circuit. The 160 volts
VLOTAUX5V 5 volts, and VLOT8V 8      dc goes through 5545 to the FET
volts. The scan derived VLOT8V,8     switch. The start voltage for the
volt supply, produces the +8VA       switching mode power supply is
supply which is applied to Pin 37    taken from the hot leg of the
of 7250 to power the Horizontal      input ac.
and Vertical sections of the IC.
The Horizontal Oscillator section    The power supply includes a single
of 7250 does not operate until the   integrated circuit, operating as a
Scan circuit is working.             free-running switching mode power
Horizontal Drive on Pin 40 is        supply. The frequency of operation
applied to 7607 to synchronize the   varies with the circuit load.
Astable Multivibrator to the         There is no separate power supply
correct frequency.                   for standby; instead, the power
                                     supply turns On when ac is
The Shutdown circuits of the set     applied. The switching regulator
monitor for excessive Beam           IC starts switching when the

                                                                 PAGE 4
                         FIGURE 2 - E8 POWER SUPPLY BLOCK

initial voltage is applied through     POWER SUPPLY   (Figure 3)
the start circuit. Inside the
switching regulator, the drive         When a 120Vac Source is connected
circuit turns the FET switch On        to the E8 Chassis, approximately
and Off to allow current to flow       160Vdc is developed by the Bridge
through the primary of the             Rectifier circuit. The 160 volts
transformer 5545. Energy stored        dc goes through the primary of
in the primary during the On-time      transformer 5545 to the transistor
is delivered to the secondaries        switch. The startup voltage for
during the Off-time. Feedback from     the IC is taken from the hot leg
the Hot secondary is used to           of the input ac through resistors
control the switching regulator.       3510 and 3530.
Positive voltage from the hot
secondary is rectified to provide      The Power Supply is a Switching
B+ for the switching regulator.        Mode type Power Supply. The
The voltages needed to operate the     frequency of operation varies with
television are developed from the      the circuit load. There is no
secondaries of 5545.                   separate power supply for standby;
                                       instead, the Power Supply turns On
                                       when AC is applied. The Switching
                                       Regulator IC starts switching when

                                                                   PAGE 5
FIGURE 3 - E8 POWER SUPPLY   PAGE 6
the initial voltage is applied       supplied to the IC at Pin 2
through the Startup circuit. The     through resistor 3528. Energy is
Switching Regulator turns the        stored in transformer 5545 during
Switch On and Off to allow current   the On-time of transistor 7518.
flow through the primary of          During the Off time of transistor
transformer 5545. Energy stored in   7518, energy is transferred to the
the primary during the On-time is    secondaries. Since resistors 3510
delivered to the secondaries         and 3530 cannot supply sufficient
during the Off-time. Feedback from   current to operate the IC in
the Hot secondary is used to         normal operation, the voltage at
control the Switching Regulator.     Pin 1 of IC 7520 drops below 9.4
Positive Voltage from the hot        volts, which is below the under-
secondary is used as B+ for the      voltage lockout reference,
Switching Regulator.                 shutting IC 7520 Off. 2540 again
                                     charges to 14.5 volts through
From the secondaries of 5541, 10     resistors 3510 and 3530 turning
to 14 volts is developed for the     the IC On for a second time.
audio circuit, 95 volts              Voltage from Hot secondary Pin 1
for the Horizontal Output, and 14    of transformer 5545 is rectified
volts for the 3.3 volt regulator     by diode 6540 charging capacitor
and the 5 volt regulator.            2540 during each startup cycle.
                                     Once 5545 stores enough energy to
STARTUP   (FIGURE 3)                 keep capacitor 2540 above 9.4
                                     volts, the IC operates normally.
AC voltage is rectified by the       Capacitor 2530 is connected to the
bridge diodes, 6502 through 6504     Soft Start circuit. The Soft Start
to produce approximately 160 volts   circuit prevents the power supply
dc. The 160 volts dc is applied to   from operating until the internal
the primary winding of 5545 and to   voltages of the IC are at the
the Drain of the switching regu-     correct level. This provides
lator FET 7518.                      additional protection to the power
                                     FET 7518.
A startup dc voltage ramp is
developed when the Hot side of the   STANDBY   (Figure 3)
ac line charges capacitor 2540
through Startup resistors 3510 and   Voltage from Pin 1 of Transformer
3530. When the voltage at            5545 is monitored by Pin 14 of the
capacitor 2540 and Pin 1 of 7520     IC and is compared to a 2.5 volt
IC reaches 14.5 volts, the under-    reference for feedback sensing.
voltage lockout of the IC is         Resistors 3538, 3539, and 3540 is
overcome.                            used to set the Bias level at Pin
                                     14 to set the Output Voltage.
The Oscillator inside the IC turns   Variable resistor 3540 is adjusted
on, driving the Flip Flop            to set the 95 volt secondary
producing a 10 to 15 volt peak to    output. When the set is turned
peak drive pulse at Pin 3, turning   Off, the reduced load on the
On transistor 7518. The drive        secondary is felt by Pin 14 of IC
voltage for the output at Pin 3 is   7520. This voltage change is too

                                                                PAGE 7
small for a voltmeter to measure.    Supply will restart. The Foldback
The output of the comparator can     input on Pin 5 provides overload
be measured at Pin 13 which will     protection. This input becomes
be approximately 1.8 volts in        inactive when Pin 5 goes above 1
Standby and 2 to 3 volts in the      volt.
Full Power Mode. The Standby
Circuit inside the IC monitors the   TROUBLESHOOTING
output of the feedback comparator
switching the Oscillator to 20KHz    In the case of a Dead Set, first
in the Standby Mode and 70KHz in     check the startup voltage at Pin 1
the Full Power Mode. In the          of IC 7520. If this voltage is
Standby Mode, the pulse width at     missing, check for an open fuse
Pin 3 of 7520 IC is reduced, which   1500, a shorted IC 7520, an open
reduces the On time of transistor    diode 6504, a shorted diode 6540,
7518.                                or open resistors 3510 and 3530.
                                     If there is no output voltage from
FULL POWER (Figure 3)                the supply, the voltage a Pin 1 of
                                     IC 7520 should be changing. This
The IC's internal comparator         voltage must go to 14.5 volts to
connected to Pin 14 senses a load    overcome the undervoltage lockout
change when the set is turned On.    of the IC. If the IC is working,
The Standby circuit switches the     a dc voltage change can be seen
output to 70KHz and increases the    with an oscilloscope at Pin 3 of
outputs On time. The DEMAG circuit   the IC at approximately one to two
at Pin 8 of the IC monitors Pin 1    second intervals. Unless the Under
of 5545 through resistor 3520.       voltage lockout is switched, the
This circuit keeps Pin 3 of the IC   Reference Section will not turn On
from going High until Pin 1          to power the Oscillator and drive
reaches 0 volts. This is to          section in the IC.
ensure that FET 7518 will not turn
on until demagnetization of          If the voltage is changing at Pin
transformer 5545 is complete. The    3 of IC 7520, check the FET 7518
purpose of this circuit is to        and the surrounding components.
increase the efficiency of the
power supply. Pin 7 of the IC        For a High Voltage shutdown
senses the voltage across resistor   problem, monitor the base of
3518 caused by the current flow      transistor 7650 with an
through transistor 7518. If this     oscilloscope in the dc mode or a
voltage exceeds 1 volt, the pulse    DVM set at the 2 volt range while
width at Pin 3 of the IC, or the     turning the set On. If a change
On time of 7518 will be reduced      of approximately 0.6 volts is
turning 7518 Off sooner. The         observed, 5545 Flyback transformer
internal Overvoltage circuit of      would be the likely cause. Also
IC 7520 monitors the VCC at Pin 1    check for the   presence of the 9
of the IC. If this voltage goes      volt scan derived source when the
above 17 volts, the Power Supply     set it turned on.
will shut down. AC power will have
to be removed before the Power

                                                                 PAGE 8
Symptoms                                 The feedback voltage at Pin 14
                                         will go to zero volts. A random
For a No Power or Dead Set condi-        drive pulse will be generated at
tion, first check for shorts on          Pin 3.
the output secondaries. Check B+
voltages at Pin 7 of transformer         If the Output drive circuit,
5545. A short on the 95 volts B+         transistor 7518 is lost, caused by
line will cause Pin 1 of IC 7520         an open resistor 3525 for example,
to pulse between 9 and 15 volts.         and IC 7520 is working, the




                       FIGURE 4 - E8 HORIZONTAL DRIVE

voltage at Pin 1 of   7520 will          set is turned On, the On/Standby
pulse between 9 and   15 volts. An       line goes High, allowing the
output pulse at Pin   3 of IC 7520       oscillator 7607 to turn On.
will be seen at the   same rate.         During Startup, this circuit
                                         operates at a higher Horizontal
E8 HORIZONTAL DRIVE   (Figure 4)         frequency. The VLOT8V source from
                                         the Sweep circuit produces the
The Power source for the                 +8VA supply which powers the
Horizontal oscillator is the +8VA        Horizontal oscillator in 7250.
supply on Pin 37. This is a scan         Horizontal drive from Pin 40 is
derived supply which is not              then fed to 7607 to synchronize
present in the Standby mode.             the oscillator in 7607 to the
During startup, the oscillator           correct Horizontal frequency.
circuit 7607 provides drive for
the Horizontal Output. During
Standby, Pin 4 is held Low keeping
this circuit turned Off. When the
                                                                    PAGE 9
FIGURE 5 - E8 HORIZONTAL OUTPUT   PAGE 10
E8 HORIZONTAL OUTPUT   (Figure 5)    High, shutting the set Off.
                                     The BCL_PROTN transistor 7401 will
Horizontal drive is fed to 7400      shut the set Off in case of exces-
and then to the Horizontal output    sive Beam Current. Excessive Beam
transistor 7402. The Flyback         Current will cause the ABLINFO
transformer, 5445, produces High     line to go Negative, which will
voltage, Focus voltage, G2           cause Zener diode 6413 to conduct.
voltage, +13 volts, -13 volts,       Diode 6414 will be   forward
Filament voltage, VLOTAUX5 volts,    biased, turning transistor 7401
and the VLOT8V supply. The HEW       On, causing the BCL_PROTN line to
protection circuit monitors the      go High.
ABLINFO (DAG) line and the -13
volt line for over voltage. If       E8 ON/OFF SHUTDOWN CIRCUIT
the voltage on the base of           (Figure 6)
transistor 7403 goes above 6.8
volts, transistor 7403 will turn     In the Standby mode, a switch
On, turning 7404 On. This will       inside 7600 holds Pin 19 Low.
cause the HEW_PROT line to go        When the set is turned On, Pin 19
High, shutting the set Off.          is released. The Standby line
                                     then goes High through resistor
The BCL_PROTN transistor 7401 will   3617-B3. The base of transistor
shut the set Off in case of          7621 goes High. The VIOTAUX13V
excessive Beam Current. Excessive    supply from the Sweep circuit is
Beam Current will cause the          applied to the collector of 7620
ABLINFO line to go Negative, which   and to the emitter of 7621 through
will cause Zener diode 6413 to       zener diode 6612. The positive
conduct. Diode 6414 will be          voltage on the emitter of 7621
forward biased, turning transistor   keeps the transistor turned Off
7401 On, causing the BCL_PROTN       during normal operation of the
line to go High.                     set. If the VIOTAUX13V supply
                                     should fail, 7621 turns On,
E8 HORIZONTAL OUTPUT   (Figure 5)    causing Pin 16 of 7600 go Low.
                                     This will turn the set Off. If
Horizontal drive is fed to 7400      the BCL_PROTN should go High,
and then to the Horizontal output    transistor 7611 will turn On
transistor 7402. The Flyback         causing Pin 16 to go Low, shutting
transformer, 5445, produces High     the set Off.
voltage, Focus voltage, G2
voltage, +13 volts, -13 volts,
Filament voltage, VLOTAUX5 volts,
and the VLOT8V   supply. The HEW
protection circuit monitors the
ABLINFO (DAG) line and the -13
volt line for over voltage. If
the voltage on the base of
transistor 7403 goes above 6.8
volts, transistor 7403 will turn
On, turning 7404 On. This will
cause the HEW_PROT line to go
                                                                  PAGE 11
FIGURE 6 -E8 POWER ON SHUTDOWN




                                 PAGE 12
                                                                     DOES THE SET                                                                                                     YOUR PROBLEM IS
                                 DOES THE SET                                                                DOES THE SET                              IS AUDIO
            START                  TURN ON
                                                     YES           SHUTDOWN AFTER             NO            HAVE A PICTURE
                                                                                                                                     YES               PRESENT
                                                                                                                                                                            YES     BEYOND THE SCOPE OF
                                                                       TURN ON                                                                                                        THIS FLOW CHART




                                      NO                                       YES            A                           NO          B                    NO



                                 IS THE 95 VOLT                                                               CHECK KEYSWITCH                              C
                                SOURCE PRESENT                  DOES PIN 19 OF 7600 GO                             I2C BUS
                               AT THE CATHODE OF
                                                   YES            HIGH (5V) WHEN THE              NO                RESET
                                   DIODE 6550                      POWER BUTTON IS                               OSCILLATOR
                                                                       PRESSED
                 E8                                                                                                                                                          CHECK RESISTOR
          TROUBLESHOOTING                                                                                                                                                   3207 3411 AND DIODE
                                                                                                                                 CHECK CONNECTIONS                                  6412                NO
               FLOW                                                                                                               BETWEEN 7250 AND
                                                                                                                                                                YES               5445 IFT
               CHART                  NO                                 YES                                                            7607




                                 MEASURE THE
                               RESISTANCE FROM
                                                                                                                                                        IS DRIVE PRESENT                          IS APPROX 8 VOLTS
                                THE CATHODE OF                     IS DRIVE PRESENT           YES             IS DRIVE PRESENT             NO           ON PIN 40 OF 7250          NO             PRESENT ON PIN 37
                                 6550 TO COLD                       ON PIN 3 OF 7607                           ON THE BASE OF
                                                                                                                                                                                                       OF 7250
                                   GROUND                                                                           7402



                                                       7607                                                                         TRANSISTOR 7908,
             TRANSISTOR 7402
                                                     RELATED             NO                                         YES                   7400                   NO               IC 7250              YES
                                                   COMPONENTS                                                                      TRANSFORMER 5444




                                                                                                                                                            IS IT THE
                                     IS THE                                                                   IS DRIVE PRESENT
                    NO          RESISTANCE > 4K
                                                                               7402               NO         ON THE COLLECTOR              YES              CORRECT
                                                                                                                                                           FREQUENCY
                                                                                                                   OF 7402



                                                                                                                                   SET IS TURNING ON       YES
             CHECK FUSE 1500         YES
              BRIDGE DIODES




                                                                                                                                             IS A VOLTAGE > 15                     RESISTORS 3530 &
                                IS 140-160 VOLTS                IS A DRIVE SIGNAL                       IS DRIVE SIGNAL
                    NO          PRESENT ON THE      YES         PRESENT ON THE           NO            PRESENT ON PIN 3        NO           VOLTS PRESENT ON            NO               3510
                                                                                                                                               PIN 1 OF 7520                          DIODE 6510
                                 DRAIN OF 7518                    DRAIN OF 7518                             OF 7520




                                                                      YES
                                                                                                            YES                                   YES
PAGE 13




                                                           CHECK FEEDBACK CIRCUIT
                                                           PIN 1 OF 5545 TO PIN 14 OF                   RESISTOR 3525
                                                                                                                                                 IC 7520
                                                                                                       TRANSISTOR 7518
                                                                      7520
                                                                                                                                                               CHECK FOR MISSING HORIZONTAL
                                          DOES THE BASE OF                         IS THE VLOTAUX13V
                                                                                                                           IS PIN 50 OF 7250 > 3.9            AND VERTICAL ON PINS 37 AND 36 OF
                   A                     7611 GOT0 0.7 VOLTS
                                           AFTER THE SET IS
                                                                     NO             SUPPLY PRESENT
                                                                                    WHEN THE SET IS
                                                                                                            YES           VOLTS AFTER TURN ON         NO                    7600
                                                                                                                                                                     PROBLEM ON I2C BUS
                                              TURNED ON                                TURNED ON




                                                  YES                                                                               YES
                                                                                          NO

                                                                                                                         POSSIBLE EXCESSIVE HIGH
                                               DOES THE                                                                          VOLTAGE
          DODES 6413, 6610                    SCREEN GO                           CHECK THE VERTICAL                           TUNING CAPS
          TRANSISTOR 7401        NO          BRIGHT AFTER                            DRIVE CIRCUIT                                 IFT
                 IFT                           THE SET IS                                                               TRANSISTORS 7403 AND 7404
                                              TURNED ON




                                                  YES
                                                                                                                                                                IC 7250

                                           RESISTOR 3416
                                            CRT BOARD

                                                                                                                                                                 YES



                                                                          INSERT A SIGNAL INTO
                                     IS OSD (ON
                                                                             THE REAR JACK                         IS THE PICTURE                          IS VIDEO PRESENT                  CHECK CONNECTIONS
               B                  SCREEN DISPLAY)
                                      PRESENT
                                                               YES         PANEL AND SELECT                           PRESENT                 NO           ON PIN 17 OF 7250       NO          ON THE PC BOARD
                                                                               THAT INPUT




                       IC 7250
                                        NO                                                                              YES



                                                                                 TUNER
                        NO         IS DRIVE SIGNAL                          SAW FILTER 1003            NO
                                                                                 IC 7250                    IS VIDEO PRESENT ON PIN
                                  PRESENT ON PINS
                                                                                                              6 OF 7250 WHEN THE
                                   19, 20 AND 21 OF
                                                                                                              TUNER IS SELECTED
                                         7250




                                        YES
                                                                                                                        YES
                                                                                                                                                      TRANSISTOR 7266
                                                                                IC 7250                                                                   BPF 1200
                                      CRT PANEL
PAGE 14




                                                                                                                  IS VIDEO PRESENT
                                                                                              YES                 ON PIN 13 OF 7250                  NO
                 IS AUDIO                                                 IS THE 14 VOLT SUPPLY
          C   PRESENT ON PIN
                15 OF 7250
                                     YES        IS THE SET MONO
                                                   OR STEREO
                                                                   MONO    PRESENT ON PIN 1 OF
                                                                                   7954
                                                                                                  NO    FUSE 1571




                   NO                                                             YES
                                                   STEREO

                 BPF 1001
                  IC 7250                                                     DOES THE DC
                                                                                                        7600 MICRO
                                                                            VOLTAGE ON PIN 4
                                                                          VARY BETWEEN 0 AND
                                                                                                  NO      CIRCUIT
                                                                                                       CONNECTIONS
                                                                                4 VOLTS
                                                 IS THE 14 VOLT
                                                 AUDIO SUPPLY
                                                    PRESENT

                                           NO
                                                                                  YES
                        FUSE 1571

                                                     YES

                                                                                IS AUDIO
                                                                            PRESENT ON PINS       NO     IC 7954
                                                                              5 & 8 OF 7954

                                                   DOES THE DC
                                                 VOLTAGE ON THE
                                                VOLUME LINE VARY
                                                 BETWEEN 0 AND 4
                                                      VOLTS
                                      YES                                         YES


                    STEREO DECODER
                         PANEL
                                                      NO                       SPEAKERS




                                                     IC 7600
                                                    CIRCUIT
                                                  CONNECTIONS
PAGE 15



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