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PSSG
PHILIPS SERVICE SOLUTIONS GROUP
H8 CHASSIS
TECHNICAL TRAINING
MANUAL
2001 RTM TRAINING
P H I L I P S philips technical training
401 e. old andrew johnson hwy
TRAINING
TECH p.o. box 555
jefferson city, tn 37760
phone: 423-475-0397
VIDEOTAP E S
fax:423-475-0221
MANUALS
email: [email protected]
TABLE OF CONTENTS
AUDIO OUTPUT 24
AUDIO SIGNAL PROCESSOR 24
BOARD LOCATIONS 2
CUSTOMER CONTROL INTERFACE 28
DOUBLE WINDOW 19
DOUBLE WINDOW VIDEO SIGNAL FLOW 19
HEADPHONE AMPLIFIER 24
HORIZONTAL AND VERTICAL DRIVE 7
HORIZONTAL OUTPUT AND SHUTDOWN 7
INTRODUCTION 1
MICROPROCESSOR 29
M-LINK 34
NON PIP VIDEO SIGNAL FLOW 8
POWER DOWN AND FRONT DETECT 6
PIP CIRCUIT 15
PIP VIDEO SIGNAL FLOW 15
SERVICE MODES 33
SIDE JACK PANEL 28
STANDARD CRT DRIVE 12
STANDBY REGULATORS AND ON/OFF 5
SWITCH MODE POWER SUPPLY 3
TROUBLESHOOTING FLOW CHARTS 35
VERTICAL OUTPUT 8
VERY FLAT CRT DRIVE 22
INTRODUCTION with the M-Link feature. The M-Link
feature allows VCRs, DVD, etc to be
The H8 TV Chassis is designed for the 2000- controlled through the TV. Up to five
2001 model years. It comes in three screen devices can be controlled. Refer to the
sizes which are 27, 32, and 36 inch. All Model to Module listing in the Service
Chassis versions have a Side Jack Panel, a Manual to determine which modules are
Component Input, and Surround Speaker in a given model.
Jacks. The Rear Jack and Side Jack Panels
are equipped with both Composite, Other features include an Audio Volume
Component, and SVHS inputs. The sets are Leveler (AVL) to compensate for
equipped with either a Standard Dark Glass changes in volume level. AutoLock
picture tube or a Very Flat Square Invar which allows certain channels, or
picture tube. programs with certain ratings to be
blocked. Each time the set is turned Off
The H8 Chassis comes in Non-PIP (Picture in and back On, the Access Code must be
Picture), Single Tuner PIP, two Tuner PIP, or reentered to view the blocked channels.
Double Window versions. Each time the User If the Customer forgets the Access Code,
selects the PIP window, the PIP window entry into the Menu to change the code
appears, changes size, then disappears. In can by obtained by entering Access
the Double Window version when the PIP Code 0711. To gain entry, the code must
On/Off button on the Remote is pressed, a be entered twice.
PIP window appears. When the button is
pressed again, the window changes size. A Format selection in the menu allows
Press it again and the picture goes to a the user to select between 4x3, Zoom, or
double window (split screen). Pressing the 16x9 aspect ratio for the picture. This is
button again, the picture returns to normal. accomplished by changing the Height
The XXPT41 and larger models are equipped and Width settings in the set.
The following table refers to the models and features:
27PT31 NON PIP
27/32/36PT41 Single Tuner PIP
27/32/36PT71 Two Tuner PIP
27/32PT81 Real Flat Invar CRT - Two Tuner PIP - SCAVEM
27/32PT91 Real Flat Invar CRT - Double Window - Guide Plus
Virtual Dolby - SCAVEM - Histogram
Page 1
H8 CHASSIS BOARD LOCATIONS
NON PIP CHASSIS VIEW
TV BLOCKING OPTIONS
Page 2
POWER SUPPLY (135 volt source). This source is sampled
by 7971 which drives the feedback
Switch Mode Supply (Figure 1) opto-isolator 7929 to set the switch time of
comparator B. This controls the On time of
The Power Supply is a Switching type supply. the internal switching FET to maintain the
The Power Supply begins operating as soon VBAT voltage at the correct level. There
as AC power is applied to the set. AC power are four output voltages from the
is applied to the Large Signal Board through transformer which are the VBAT voltage, 8
Fuse 1900 and applied to the Bridge Rectifier volts to the 5 and 3.3 volt regulators, 8
6915. The rectified B+ voltage is applied to volts unregulated, and 27 volts for the
the regulator switching IC, 7921, through Pins Audio Output circuit.
6 and 3 of transformer 5912. Startup voltage
for the supply is applied to Pin 4 through To troubleshoot the Power Supply, first
resistors 3914 and 3913. The Zener Diode check the VBAT (135 volt source). If this
6921 prevents the voltage on Pin 4 from voltage is missing, check for a short on the
exceeding 33 volts in case the Regulator IC is VBAT line. The most likely cause would be
not working. When the voltage on Pin 4 a shorted Horizontal Output Transistor. If
reaches 16 volts, the Oscillator inside the IC the voltage is pulsing or is Low, check the
begins operating. Once the Supply is in full feedback circuit, 7971 and 7929. Also
operation, the operating voltage for the supply check Fuse 1941 on the 8 volt unregulated
is supplied by Pin 8 of 5912 and is rectified by supply. This line supplies the operating
6929. The Oscillator drives the internal voltage for the feedback circuit. Next,
switching FET. When the FET is On, energy check the B+ voltage for 7921 on Pin 3. If
is stored in 5912. When the FET is Off, the drive signal is pulsing On and Off on
energy is transferred to the secondary of Pin 3, there may be a problem with the
5912. The Frequency and On time of the feedback circuit. If there is no drive signal
internal switching FET is determined by the on Pin 3, check for the operating voltage
Internal Comparator, the internal RC network, on Pin 4. This voltage must ramp to 16
and the Magnetizing Inductance of the volts to start the supply. If it is missing or
Transformer. The Internal RC network also is not ramping to 16 volts, check 3913,
determines the Off time of the FET switch. 3914, and 2919. Regulation problems
The On Time is determined by the ramping could be caused by resistors 3923 or 3924
voltage across 3924, 3923, the feedback changing value. If 7921 should fail, these
voltage from Pin 8 of the transformer, and the resistors should be changed by using
voltage from the feedback opto-isolator. The original parts only.
Reference Voltage for the supply is the VBAT
Page 3
Set Turned On.
Set in Standby.
Page 4 Figure 1 - Switch Mode Power Supply
Standby Regulators and On/Off (Figure 2) drive for the 3.3 volt regulator. The 8 volt
unregulated supply is applied to 7942,
The voltage from jumper 9964 (approximately which is a switched 8 volt regulator. The
8 volts) is used to produce the 3.3 volt Standby line goes Low when the set is
standby, 5 volt standby, 5 volt remote control, turned On, turning transistor 7944 Off,
and switched 8 volt supplies. The voltage is switching 7942 On. The switched 8 volt
applied to transistor 7965 to produce the 3.3 supplies the Horizontal Oscillator in the
volt Standby supply. When the set is in the Signal Processor IC located on the SSB.
Standby mode, transistor 7944 is turned On,
turning 7922 On, providing a extra current
Figure 2 - Standby Regulators and On/Off
Five Volt Switch (Figure 3) power is removed from the set while it is
being turned On. This is necessary to
The Switched 8 volt supply also turns On the prevent a POP in the speaker while the set
5 volt regulator, 7967, to produce a switched 5 is powering down.
volt supply. The Switched 5 volt supply turns
transistor 7950 On. This provides a load on
the 27 volt Audio Supply line to discharge any
remaining voltage on the line in the event that
Page 5
Figure 3 - 5 Volt Switch
Power Down and Front Detect (Figure 4) lines, blanking the CRT. Transistor 7277
will continue to conduct until Capacitor
The Power-Down and Front Detect circuits 2284 has discharged. In the same manner,
signal the Microprocessor in case power is 7990 will be turned Off, turning 7991 Off,
removed from the set. The Microprocessor which will turn 7992 On, causing the Front-
will store the customer settings before shutting Detect line to go Low. This will prevent the
the set down. Diode 6942 produces a negative Microprocessor from receiving any
voltage to turn transistor 7987 On, keeping the commands while the set is being shut
Power-Down line High. This keeps transistor down. If there is a problem in this circuit
7277 turned Off. If power is removed from the which causes the Front Detect line to go
set, the negative voltage will discharge before Low, the Microprocessor will not respond to
the operating voltage for the set falls. any commands from the Keyboard or
Transistor 7987 will turn Off. 7277 will then Remote.
turn On, placing a High on the RGB CRT drive
Figure 4 - Power Down and Front Detect
Page 6
SWEEP AND SHUTDOWN CIRCUITS One function is to provide Horizontal
Phase correction for the Horizontal Drive.
The other is to provide Flash protection in
Horizontal and Vertical Drive (Figure 5) case of an overvoltage on the I-Beam line.
If the pulse on Pin 58 exceeds 6 volts,
The 3.3 volts Standby supply provides power Horizontal Drive will be shut Off. It will be
to 7301 on Pin 14 for a Horizontal Soft Start. necessary to recycle power to the set to
The Standby line from the Microprocessor restore operation. This failure will
turns the +8 volt supply On to provide power generate an error code 1 indicating a
for the Sync circuits when the set is turned problem with the Horizontal Output
On. The Horizontal Output on Pin 56 is Transformer or with the CRT drive circuit.
switched On by the Microprocessor via the The PROTN line is connected to the
I2C buss, after the Soft Start is complete. IBEAM (Dag) line. This voltage is used to
Vertical Drive, labeled Frame-Drive, is output make minor adjustments in the Vertical
on Pins 63 and 64. In the event the Vertical Drive to compensate for minor changes in
Output should fail, the Signal Processor 7301 Beam Current. This line is also connected
will blank the RGB output. East-West Drive to the Overvoltage Detection circuit. If this
on Pin 62 provides linearity correction for the voltage exceeds 3.9 volts, the Horizontal
Very Flat and Larger CRTs. Sandcastle is Drive will be shut Off. The Microprocessor
output on Pin 57. The Dynamic Phase will show an error code 3.
Correction input on Pin 58 has two functions.
Figure 5 - Horizontal and Vertical Drive
Horizontal Output and Shutdown (Figure 6) Drive circuit is present. The East West
Drive circuit also has a protection circuit to
Horizontal Drive (LINEDRIVE1) is fed to detect the loss of Horizontal drive. In nor-
transistor 7481 and coupled through mal operation, 7470 is switched by the
transformer 5406 to the Horizontal Output EW-Drive. The pulse width is too narrow
transistor 7410. In sets with the Very Flat to develop the necessary voltage to turn
CRT and larger screen sizes, an East West 7478 On. Current flow through 3479
keeps transistor 7480 turned On, keeping
Page 7
the PROT-UP line Low. If Horizontal drive or a +200 volt supply for the CRT output
EW Drive is lost, 7470 is turned On, applying circuit. The Horizontal Drive signal is
a positive voltage to the base of 7478, turning sampled by 3411, 3412, and 3413 to
it On. Transistor 7480 turns Off, causing the produce the HFB (Horizontal Feedback
PROT-UP line to go High through resistor signal) which is used to provide Sync for
3480, which will cause the Microprocessor to the Small Signal Board.
turn the set Off.
Vertical Output (Figure 7)
When the Driver Transistor 7481 is
conducting, the voltage drop across resistors Positive and Negative Vertical drive from
3404, 3405, and 3406 turns transistor 7408 the Small Signal Board is fed to the
On. This circuit supplies the 33 volt tuning Vertical Output IC7501 which drives the
voltage and bias voltage to the IBEAM (Dag) Vertical Yoke. The Vertical Pulse on Pin3
circuit. Transistor 7440 also detects the drives 7513 to produce the VFB (Vertical
failure of Horizontal Drive or Overcurrent. If Feedback signal) for the Small Signal
there is no Horizontal drive to 7481, 7408 will Board. A failure in the Vertical Output
turn Off, removing the 33 volt tuning voltage. circuit will be detected by the Signal
Transistor 7440 will turn On, causing the Processor on the SSB by sensing the
PROT-UP to go High, which will cause the set Frame Drive line and by the
to shut Off. Voltage from Pin 5 of the IFT is Microprocessor sensing the loss of the
rectified by 6461 and applied to 7464. If this VFB pulse. While turning the set On,
voltage exceeds 5.4 volts, 7464 will turn On, check the plus and minus 13 volt sources.
turning 7467 On, applying the +8 volt supply Then check for Vertical Drive on Pin 7 with
to the PROTN line, shutting the set Off. The an oscilloscope while turning the set On.
IFT produces a plus and minus 13 volt supply
for the Vertical Output circuit. The voltage on
Pin 9 of the IFT is rectified by 6445 to produce
VIDEO SIGNAL FLOW located on the Side Jack Panel. All of
these inputs are fed to the Small Signal
Board, SSB, which plugs into the Large
There are four variations in the signal flow Signal panel. The Tuner IF is fed to the
path for the H8 chassis. They are the Non- SAW filter, 1451, and then to the Signal
PIP, the Single Tuner PIP, the Dual Tuner PIP, Processor, 7301, on Pins 1 and 2.
and the Double Window version.
Composite Video is output on Pin 16 and is
NON PIP Video Signal Flow (Figure 8) buffered by 7305 and 7331. Baseband
Audio is output on Pin 27 and is buffered
The first version to be discussed is the Non by 7307. This signal is fed to the Sound
PIP chassis video path. The Main Tuner, AV1, Decoder IC for processing. The Video
AV2, and Component Inputs are located on Signal is then fed to 7301 on Pin 24 which
the Large Signal panel. The AV3 input is selects between the composite signal and
Page 8
Figure 6 - Horizontal Output and Shutdown Page 9
Page 10 Figure 7 - Vertical Output
Figure 8 - Non PIP H8 Video Signal Flow Page 11
the MAIN-CVBS-EXT-IN. The MAIN-CVBS- Display) is added. The signal is then fed
EXT-IN is selected composite Video or to the RGB output circuit and to the CRT.
Luminance from either AV1, AV2, or AV3. A Test Waveform is first sent to the CRT
These signals are selected by the Switch IC on the RGB lines. When this Test Signal is
7401 which is controlled by two lines from the detected by the CRT drive circuits, the
Microprocessor, which are SEL-MAIN-R1R2 signal is fed back to 7301 on Pin 3 on the
and SEL-MAIN-FRNT-RR. If SVHS is the CUTOFF LINE. When these are detected,
selected input, the Y (Luminance signal) is fed the Video signal is then output on the
to Pin 29 by 7401. Selected Video or Y from RGB lines.
7301 is output on Pin 54 and is buffered by
7421. If the output of 7301 is Composite Standard CRT Drive (Figure 9)
Video, the Comb Filter IC 7405 will output Y
and C on Pins 15 and 13. Switching IC 7407 The CRT drive signal is fed to 7830 which
selects YC from either the Comb Filter or Y drives the CRT. As mentioned previously,
from 7421. If one of the SVHS inputs is a Test Signal is sent to 7830 and to the
selected, 7401 outputs C (Chrominance) on CRT. The Waveform on the left shows this
Pin 14 and is buffered by 7412-B before being Test Signal. When 7830 senses the
fed to 7407. IC 7407 is switched by Pin 22 of correct current flow in the CRT, the Test
7301. A High on Pin 22 causes Pins 12 and Signal is sent to the SSB via the CUTOFF
13 to switch the inputs on Pins 1 and 11. line. The Picture RGB signal is then fed to
When Pin 22 is Low, 7425 is turned Off the CRT Board. This waveform is shown
switching Pins 5 and 6 High, selecting the on the right. If the CRT is defective or
inputs on Pins 4 and 8. Selected YC is then unplugged, no pulse will be ouput on Pin 4.
fed to Pins 21 and 20 of 7301 where they are Therefore, the Signal Processor IC on the
fed to a Delay Line and Demodulator. The SSB will not output the Video Signal on the
output of the Demodulator and Delay Line is RGB lines.
fed to a YUV switch, which selects between
this signal and external YUV (Component
Input) from the Jacks on the Large Signal
panel. The selected YUV signal is then fed
back into 7301 on Pins 39, 47, and 48. The
signal is then fed to a YUV processing circuit
and to an RGB Matrix where OSD (On Screen
Page 12 Figure 9 - Standard CRT Drive Circuit
Figure 10 - Video Signal Flow with Standard PIP Page 13
Page 14 Figure 11 - Single Window PIP
PIP (Picture in Picture) Video Flow (Figure circuits on the PIP panel.
10)
There are two PIP chassis versions which are PIP Circuit (Figure 11)
the Single Tuner and Two Tuner sets. Video
Signal flow for the Single Tuner PIP version is The PIP comes in two versions, Single
the same as the Two Tuner version, except Tuner with no tuner on the PIP panel and
the Composite Video from Pin 16 of 7301 is two tuner versions with the second tuner
routed through the Large Signal Board (LSB) located on the PIP module. Output of the
to the PIP module and back to the 1333 second tuner is fed to the SAW FILTER
Sound Trap in the Two Tuner version. In the 1901, and to the Signal Processor 7914.
Single Tuner version, Video from Pin 16 is Composite Video is fed to the Switch 7916
routed through jumper 4308. The second which selects between the PIP tuner or
Tuner is located on the PIP panel. Baseband selected Composite Video from the SSB.
audio is output on Pin 27 and is buffered by There are two sets of switches: one to
7331. In the Two Tuner version, the Audio is select Video for the main picture, CVBS-
combined with the composite video before PIP_TUN1-2-CVBS-IN, and one to select
being fed to the PIP panel. Selected Video Video for the PIP window. Selected Video
with the Baseband Audio from the PIP panel for the PIP window is fed to 7801, which
is fed through jumper 4307 to the Audio selects between the output of 7916 or from
Processor. In the Single Tuner version, AV1, AV2, or the Side Jack panel (labeled
Baseband Audio from 7331 is fed through Front In). The output of 7801 is buffered
jumper 4304 to the Audio Processor. YUV by a four transistor amplifier and then fed
signal from Pins 40, 45, and 46 are routed to Pin 22 of 7803, PIP processor. The PIP
through the PIP module where the PIP processor is controlled by the I2C buss
window Video is inserted. Other Video signal (SDA and SCL). It is kept in sync by the
flows are the same as for the Non-PIP Vertical sync pulse (VFB) and the
version. The Single and Two Tuner PIP Horizontal sync pulse (SANDCASTLE).
circuits are the same except for the addition of The PIP window video is output as YUV to
the second Tuner and Signal processing the YUV switch, 7919. The signal is
combined with the main picture YUV from
Model 27PT81 - Very Flat CRT - Two
Tuner PIP
Page 15
the SSB panel on connector 0205. The control the tuner aux switching IC 7801.
combined YUV signal is output on Pins 12, 11,
and 10 to the SSB. PIP Power Supply (Figure 13)
PIP Switching (Figure 12) The PIP panel is powered by +5 volt, +8
volt, and +33 volt supplies from the Large
Control for the PIP panel is performed by Signal Board (LSB). A 3.3 volt regulator
7910 via the I2C buss. SEL_TUNER1 and supplies power to the PIP processor, 7803.
SEL_TUNER2 control the composite
switching to the SSB panel. S1, S2, and S3
Page 16
Figure 12 - Single Window PIP Control
Figure 13 - PIP Power Supply
Page 17
Page 18 Figure 14 - Video Signal Flow with PIP/Double Window
Video Signal Flow with Double Window panel. These selections are fed to 7301
(Figure 14) on Pins 24, 29, and 20. If Composite
Video is selected, it is fed to a YC
The XXPT91 versions of the H8 chassis have separator, then to a Delay Line and
the DOUBLE WINDOW panels. This allows Demodulator. If it is a YC signal, it
for both a single PIP window and a split bypasses the YC separator. The YUV
screen. Each Time the PIP On/Off button on signal is then fed to the YUV switch which
the remote is selected, the PIP window goes selects between the output of the Delay
from a small window to a large window and Line and Demodulator, and external YUV
then to a split screen. Composite Video and from the Large Signal Board. The YUV
YUV switching between the PIP panel and the (SY, SU, and SV) is output to the PIP
SSB is the same as the standard PIP. Two processor IC. Selected Composite Video
other differences are the Histogram IC 7403 is fed to the V-Chip processor. V-Chip
and the Gemstar module. The component processing for the main picture is done by
YUV input is routed through the Gemstar the Microprocessor on the SSB.
module. If there is a Component input to the
set, such as the output of a DVD, it is Double Window Output (Figure 16)
combined with the on-screen Gemstar
information in the Gemstar module and output The PIP or Double Window YUV signal is
from the Gemstar module as RGB. The RGB fed to the PIP/DW processor, 7801. The
signal is then fed to the RGB/YUV switch in I2C buss controls the IC from the
7301. Another addition to this chassis version Microprocessor on the SSB. The PIP/DW
is the Histogram IC, 7403. The Histogram cir- processor outputs YUV for the PIP window
cuit is a Contrast improvement circuit. The Y or Split Screen to the YUV switch 7803
or Luminance signal is divided into 5 discrete where it is mixed with the YUV signal from
histogram sections for processing. Each level the SSB for the main picture. The Fast
is adjusted to improve the overall contrast Blanking line from 7801 on Pin 68 controls
level. The Blue Stretch circuit shifts colors the switch point in which the PIP window
near white toward Blue to give a brighter or Split Screen is inserted. The SDA and
impression. The HIS-OFF is used to switch SCL lines are switched by the +3VD line.
the Histogram circuit On and Off. The PIP processor is powered by the +3
volt supply. The +3.3 volt, +3 volt, and
Double Window Tuner and Video Switching +3VD volt supplies are produced by the
(Figure 15) regulator 7802 which is driven by the +5VS
supply. This supply is switched On when
The PIP/Double Window panel allows for both the PIP window is selected.
a standard PIP window and a split screen.
The PIP/Double Window module has a Double Window Control and Power Supply
separate Tuner, SAW filter, and Signal (Figure 17)
Processor. The output of the Signal
Processor, 7301, on Pin 16 is fed to switching The PIP/Double Window module is
IC 7402 which selects between the PIP Tuner controlled by the I2C buss through 7403 on
and Composite Video from the SSB for the PIP module. Pins 4, 5, 6, and 7
feedback to the SSB on Pin 15 or Video for perform Video selection functions. Pin 10
the PIP window on Pin 14. IC 7401 selects produces a reset signal for the Guide Plus
Composite Video or Luminance (Y) from AV1, module. Pin 12 controls the +5VS and
AV2, or AV3. The other part of 7401 selects +8VS supplies.
Chroma from the rear Jack or the Side Jack
Page 19
Page 20 Figure 15 - PIP/Double Window Tuner and Video Switching
Figure 16 - PIP/Double Window Output Page 21
Figure 17 - PIP/Double Window Control and Power Supply
Very Flat CRT Drive Circuit (Figure 18)
The CRT panel for the Very Flat CRT's has an
SVM circuit to sharpen the transitions from
dark to light and light to dark. The RGB
signals are combined and fed to 7860 which
performs impedance matching. The signal is
then buffered by 7861. Capacitors 2867,
2870, and 2874 along with diodes 6867 and
6868 act as a differentiator to separate the
pulses for the contrast difference. Transistors
7862 and 7863 drive the SVM yoke. To
ensure the SVM switching occurs at the
correct point in the picture, delay lines 5886,
5888, and 5890 delay the RGB signal to the
RGB amplifier.
Model 27PT91 with PIP/Double Window and
Gemstar
Page 22
Figure 18 - Flat CRT Drive Page 23
AUDIO SIGNAL PATH Right Channels. The Amplifier is powered
by a 27 volt supply which is present as
Audio Signal Processing (Figure 19) soon as power is applied to the set. When
the set is in the Stand By mode, a High on
All Audio Processing is performed by 7651, the Stand By line turns transistors 7710
which is located on the SSB. The Sound IF is and 7704 On placing a Low on Pins 11 and
fed to Pin 50 and to the Sound Demodulator 3 of 7702. This turns the output stage of
for decoding. The internal Switch selects 7702 Off during Stand By. When the
between AV1, AV2, and AV3. The Audio is User selects the Mute function, the
digitally processed inside the IC to separate SOUND-ENABLE line goes Low, turning
the Second Audio Program and process transistor 7701 Off. Pin 8 of 7702 will go
volume levels to maintain a constant audio High, muting drive to the output stage.
level if the AVL feature is selected by the When Sound is present, the SOUND-
user. The AUDIO-L and AUDIO-R are fed to ENABLE line is High. When Power is
the audio amplifier on the Large Signal Board. removed from the set, the POWER-DOWN
The Headphone output on Pins 18 and 17 is line goes Low, turning transistor 7711 On,
fed to the Headphone amplifier on the LSB. causing the SOUND-ENABLE line to go
SC1_OUT-L and SC1_OUT_R on Pins 28 and Low. This mutes the audio output during
29 are fed to the monitor audio jacks on the Power Down to prevent a POP in the
LSB. The AUDIO-SW, Subwoofer output, is speakers.
fed to the LSB and then to the Subwoofer
module. Audio frequencies above 100 Hz are Headphone Amplifier (Figure 21)
filtered out for this output. Volume levels are
controlled in the Audio Processor IC. Headphone audio from the SSB is fed to
the Headphone Amplifier, 7703-A, located
Audio Amplifier (Figure 20) on the LSB. The Audio is then output to
the Side Jack panel. This circuit is
Audio from the SSB is fed to the Audio powered by the +5 volt supply.
Amplifier on the LSB. Left Channel Audio is
fed to Pin 2 of 7702 while Right Channel
Audio is fed to Pin 5. Audio is output to the
speakers on Pins 12 and 7. Left and Right
outputs are also fed to the Surround Sound
Speaker Jack. The output of the Surround
Jacks is the difference between the Left and
Page 24
Figure 19 - Audio Signal Processing Page 25
Page 26 Figure 20 - Audio Amplifier
Figure 21 - Headphone Amplifier
H8 Side Jack panel
Page 27
Figure 22 - Side Jack Panel
Side Jack Panel (Figure 22) resistor 3295 is taken out of the circuit
causing the voltage to increase to 1.35
The Side Jack panel is the AV3 input in the volts. The Microprocessor will activate the
Customer Menu. It has a Composite Video Mute line. With only the SVHS connected,
Input, SVHS Input, and a Stereo Audio input. resistor 3289 is out of the circuit, causing
It also has a headphone output. If an SVHS the FRONT-DETECT line to increase to
connector is plugged into the Side Jack panel, 1.99 volts. An indicator will appear in the
the Composite Video input is muted. The Menu to indicate that SVHS is present on
Audio inputs are designed so that if audio is AV3. With both a SVHS and Headphone
plugged into only one input, the signal will be connected to the Side Jack panel, both
fed to both the Left and Right Channel lines. resistors are out of the circuit and the
The Front Detect line tells the Microprocessor voltage will increase to 3.39 volts. This will
if an SVHS or Headphone is connected to the give the SVHS indication in the Menu and
Side Jack panel. In normal operation, the Mute the Audio. If the Side Jack panel is
FRONT-DETECT line is approximately 1.05 disconnected while troubleshooting the set,
volt. When a Headphone is plugged in, the Audio will be muted.
Page 28
Microprocessor (Figure 23) Reset. When the set is operating normally,
the Reset pin should measure Low. The
The Microprocessor, 7064, is located on the FRONT-DETECT line monitors the Side
SSB. User control of the Microprocessor is Jack panel for the Headphone or an SVHS
accomplished via the Keyboard or Remote. In connection. It also monitors 7992 for a
case of Overcurrent or a failure in the Power Down. A Low on Pin 6 will disable
Horizontal sweep circuit, The PROT-UP line the Keyboard and IR inputs.
will go High turning transistor 7276 On,
placing a Low on Pin 5 of the Keyboard line. Customer Control Interface (Figure 24)
The Microprocessor will then shut the set Off.
Composite Video for Data Capture, for Closed The Keyboard line is a voltage level
Caption or Text, is fed to the IC on Pins 32 controlled input. With no buttons pressed,
and 31. The Microprocessor is connected to this line should read approximately 3.38
the Memory IC 7066 which stores information volts when the set is On. It will be
for Option Codes, Geometry, Gray Scale, and approximately 0.2 volts higher when the
Customer settings. Two I2C busses, SDA and set is in Standby. In the XXPT31 versions,
SDA-2, communicate with the set along with the Keyboard Switches are located on the
several analog outputs. The set is turned On LSB. In the XXPT41 and above models,
when the STAND BY line on Pin 13 is pulled the Keyboard Switches are located on the
Low by 7064. Horizontal and Vertical sync for Top Control panel for Volume Down,
the On-Screen display is fed to the IC on Pins Volume Up, Channel Up, and Channel
53 and 55. The Reset for the Microprocessor Down. The Power Switch is located on the
is located on the SSB. Transistor 7063 turns Front Interface panel.
Off as 2043 charges causing Pin 73 to go
High when power is first applied to the set for
Page 29
Page 30 Figure 23 - Microprocessor
Figure 24 - Customer Control Interface
Page 31
Page 32 Figure 25 - Service Alignment Mode (SAM) Menus
SERVICE MODES repeat itself for the next Error Code. When
all of the Error Codes have been displayed,
All of the adjustments in the set are performed the LED will light for three seconds. The
via the On-Screen Service mode. There are procedure will then repeat itself.
three different Service Modes. The SDM
(Service Default Mode) allows Error Codes to Service Alignment Mode (SAM) (Figure
be read through an On-Screen menu or from 25)
a blinking Power light. It also pre-sets certain
conditions and disables certain functions. The Service Alignment Mode is used to
read Error Codes, Reset Error Codes, Set
The next Service mode is the SAM (Service Option Codes, and perform Service
Adjustment Mode). This mode is used to Alignments. Pressing 0-6-2-5-9-6-Status
align the set, adjust option settings, and read on the remote control transmitter enters the
and clear the error buffer. SAM. To save the Error Codes, remove
AC power to the set without turning it Off.
The final mode is the CSM (Customer Service When power is reapplied and the set is
Mode). This mode can be entered by the turned On, the SAM will still be active. Use
Customer on instruction of the Service the Cursor Up-Down keys to select a
Technician to read error codes. function in the menu. Press the Cursor
Right-Left keys to select a function or make
Service Default Mode (SDM) an adjustment. Under White Tone, there
are three sets of settings which are
The Service Default Mode can be entered by Normal, Cool, and Warm. Normal set-
pressing 0-6-2-5-9-6-Menu, on the remote tings is for a normal Gray Scale and should
control transmitter. The Service Default Mode be selected when doing a White Balance or
sets the following conditions: Gray Scale adjustment. When the User
selects Cool, a slight Blue tint is added to
Tuning Frequency is set to 61.25 MHz the picture. When Warm is selected, a
(Channel 3). slight Red tint is added to the picture.
Volume level set to 25%. Refer to the Service Manual for the proper
Other Picture and Sound settings set to alignment procedure.
50%.
Timer, Sleep Timer, Parental Lock, and To Save changes in SAM, return to the
Blue Mute disabled. main menu and turn the set Off from either
the Remote Control or the Front Keyboard.
The SDM can also be entered by shorting
jumpers 9261 and 9262 while turning the set Customer Service Mode (CSM)
On. Caution should be used when using this
procedure because the 5-volt protection is The Customer Service Mode allows the
disabled. After entering the SDM, the Error Customer to read the Error codes upon
Codes can be read by the blinking power instruction form the Technician.
LED. The LED will blink the number of times
equal to the value of the error codes. After The Customer Service Mode can be
the SDM has been entered, the LED will light entered by pressing the Mute button on the
for 750 milliseconds, followed by a pause of Remote Control and any key on the set
1500 milliseconds, followed by the number of Keyboard at the same time.
blinks equal to the error code. If more than
one error code is present, the procedure will
Page 33
Figure 26 - M-Link driver circuit
M-link (Figure 26)
The M-Link feature is on all sets above models
XXPT41 and above. This feature allows
external devices such as DVD players and
VCRs to be controlled by the TV set. The M-
Link panel has a driver circuit which is
connected to the I2C buss to drive the IR
Blaster which communicates with external
devices. The Surround Sound Speaker Jacks
are also located on the M-Link panel.
MLINK HOOKUP
Page 34
DEAD SET/ IS 135 VOLTS (VBAT) DOES A VOLTAGE APPEAR
DOES APPROX 14 VOLTS CHECK FUSE 1941 AND
PRESENT ON THE CATHODE NO MOMENTARILY ON THE CATHODE YES APPEAR MOMENTARILY
NO RELATED
SHUTDOWN OF DIODE 6938? OF 6938 WHEN POWER IS
ON THE CATHODE OF COMPONENTS.
APPLIED TO THE SET?
6941?
CHECK THE FEEDBACK PATH,
CHECK 7965 AND YES 7929, 7971, AND RELATED
NO RELATED YES NO COMPONENTS.
COMPONENTS.
IS A SMALL VOLTAGE CHECK FOR A SHORT
IS THE 3.3 VOLT
DOES THE STAND-BY LINE
PRESENT ON THE YES ON THE VBAT (135V) CHECK 7921, 2919,
STANDBY VOLTAGE NO GO LOW WHEN THE POWER
CATHODE OF 6941? LINE. AND RELATED
PRESENT? COMPONENTS.
BUTTON IS PRESSED?
YES
CHECK 7991, 7990, CHECK 7944, 7942,
NO
YES AND RELATED YES AND RELATED
COMPONENTS. COMPONENTS.
IS A VOLTAGE > 16
IS 130 TO 160 VOLTS
IS THE VOLTAGE ON PIN 4 NO VOLTS PRESENT ON
IS THE FRONT DOES THE 8 VOLT NO PRESENT ON PIN 3 OF 7921? YES OF 7921 CHANGING PIN 4 OF 7921?
DETECT LINE < 1 YES SUPPLY TURN ON? THIS IS RELATIVE TO HOT
BETWEEN 11 AND 16
VOLT DC? GROUND.
VOLTS?
CHECK 5912, 3924,
CHECK THE CHECK 7967 AND
3929, 6929, 3923, 7929,
KEYBOARD AND YES RELATED
CONNECTIONS. COMPONENTS.
AND RELATED CHECK 7921. NO
NO COMPONENTS. YES
NO
CHECK 7921, 6921, 3914,
3913, AND RELATED
DOES THE 5 VOLT CHECK 7921, FUSE
NO SUPPLY TURN ON?
NO COMPONENTS.
1900, BRIDGE 6915, NO
DOES THE KEYBOARD LINE AND RELATED IS DRIVE SIGNAL
(PIN 2 OF 0226 CHANGE TO 0.66
YES PRESENT ON PIN 3
COMPONENTS.
VOLTS WHEN THE POWER OF 7921? CHECK 7501, YOKES,
REPLACE THE SMALL
BUTTON IS PRESSED? AND RELATED
SIGNAL BOARD (SSB)
YES COMPONENTS.
IS VERTICAL DRIVE
REPLACE THE SMALL PRESENT ON PIN 7 OF
YES
NO
YES IS HORIZONTAL NO A SIGNAL BOARD (SSB). 7501?
(LINEDRIVE1)
PRESENT? CHECK 3448, 3449,
AND RELATED NO
CHANGE THE SMALL COMPONENTS.
SIGNAL BOARD (SSB).
YES YES
YES
IS THE VERTICAL IS +13 VOLTS DC IS -13 VOLTS DC
CHECK 7481, 7410,
FEEDBACK PULSE PRESENT ON PIN 2 OF PRESENT ON PIN 4 OF
5431, AND RELATED NO IS HIGH VOLTAGE YES PRESENT WHEN THE
NO 7501 WHEN THE SET IS
YES 7501 WHEN THE SET IS
COMPONENTS. PRESENT?
SET IS TURNED ON? TURNED ON? TURNED ON?
Page 35
CHECK 3446, 3447,
AND RELATED NO
COMPONENTS.
Page 36
DOES THE BASE OF 7440 GO
DOES THE PROT-UP LINE GO DOES THE COLLECTOR OF
A HIGH WHEN THE SET IS
YES LOWER THAN THE EMITTER
WHEN THE SET IS TURNED ON?
YES 7408 GO TO 135 VOLTS WHEN
NO CHECK 7408 .
TURNED ON? LOW IS 0 THE SET IS TURNED ON?
VOLTS.
NO NO THE DAG (IBEAM) VOLTAGE IS
GOING LOW. CHECK 6439, 5431,
YES +200 VOLT SUPPLY, AND CRT
CIRCUITS.
CHECK 7464, 7467,
CHANGE THE SMALL DOES THE PROTN LINE
SIGNAL BOARD (SSB).
NO GO HIGH WHEN THE
YES 5431, AND RELATED
COMPONENTS.
POWER BUTTON IS
PRESSED? IS 7440 OPEN? YES REPLACE
NO
CHECK 7470, 7478,
DOES THE BASE OF 7480 GO
AND RELATED YES LOW WHEN THE POWER
NO CHECK 7480.
COMPONENTS.
BUTTON IS PRESSED?
SELECT AUX 1 IN THE SELECT THE TUNER
IS OSD (ON IS A PICTURE IS A PICTURE IS APPROX 33
MENU AND INSERT A INPUT AND SUB AN IF
NO PICTURE SCREEN DISPLAY) YES SIGNAL INTO THAT
PRESENT ON THE YES SIGNAL ON PIN 68 OF
PRESENT ON YES VOLTS PRESENT
PRESENT? TV SCREEN? SCREEN? ON PIN 9 OF THE
INPUT. 0226.
TUNER?
NO REPLACE THE SMALL
CHANGE THE SMALL
REPLACE THE SMALL SIGNAL BOARD (SSB).
NO SIGNAL PANEL (SSB).
NO
SIGNAL BOARD (SSB).
CHECK 3409 AND 6481.
DOES THE SET YES
NO NO
NO HAVE A SECOND
IS A NEGATIVE GOING PULSE TUNER?
YES YES PRESENT ON PINS 7, 8, AND 9 OF DOES THE SET HAVE A
7830? THIS PULSE SHOULD BE 100 PIP (PICTURE IN PICTURE)
VOLTS P-P OR GREATER. PANEL?
CHECK 5261 AND IS 5 VOLTS DC
YES RELATED NO PRESENT ON PIN 6
CONNECTIONS. OF THE TUNER?
CHANGE THE SMALL
IS A POSITIVE GOING NO SIGNAL BOARD (SSB).
PULSE PRESENT ON NO YES
PIN 5 OF 7830?
IS COMPOSITE
REPLACE THE SMALL YES
IS THE YUV VIDEO PRESENT NO SIGNAL BOARD (SSB).
SIGNAL PRESENT ON 0272, PIN 3?
ON 0205, PINS 1, 3,
AND 4?
NO IS A 2 VOLT P-P OR GREATER CHANGE THE SMALL
PULSE PRESENT ON PINS 1, 2, IS CLOCK AND DATA
SIGNAL BOARD (SSB). YES
AND 3 OF 7830?
YES NO PRESENT ON PINS 4 AND
YES 5 OF THE TUNER?
IC 7830 OR THE CRT IS
THE PROBLEM.
CHECK 7830 AND YES IS COMPOSITE CHECK CIRCUIT
NO RELATED VIDEO PRESENT BOARD
COMPONENTS. IS THE YUV ON 0272, PIN1? CONNECTIONS. YES
SIGNAL PRESENT
ON 0205, PINS 6, 8,
CHANGE THE SMALL AND 9?
SIGNAL BOARD (SSB).
YES REPLACE THE TUNER.
CHECK 7916 AND 7910 NO CHECK 7402 AND 7403
ON THE DOUBLE
REPLACE THE SMALL ON THE PIP MODULE.
WINDOW PANEL.
SIGNAL BOARD (SSB). NO
IS THE SET AN
NO XXPT91 MODEL?
YES
CHECK 7919 ON THE IS THE SET AN
PIP MODULE.
NO XXPT91 MODEL?
YES
Page 37
CHECK 7803 ON THE
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