Toshiba PJTV7 Schematic
FOREWORD
The material presented in this manual is provided for the technical training of TACP employees
and qualified service personnel only.
This manual is intended as a supplement to the Toshiba Service Training Manual, " Servicing the
N5SS Color Television Chassis/Digital Convergence", File Number NTDPJTV04. This manual
concentrates on the changes in the Video and Audio signal paths, with additional information on
troubleshooting power supply shut down circuits.
The specific circuit reference designations, pin numbers, etc., are taken from the TP50G60/
TP55G60 Service Manual, File Number 020-9711. The diagrams in this manual are simplified for
training and should be used as a reference guide only when servicing the N7SS PJTV Chassis. Refer
to the applicable service data for detailed adjustment and servicing procedures.
NTDPJTV07
SERVICING TOSHIBA'S N7SS TELEVISION CHASSIS
©1997
TOSHIBA AMERICA CONSUMER PRODUCTS, INC.
National Service Division
National Training Department
1420B Toshiba Drive
Lebanon, TN 37087
(615) 449-2360
No part of this manual may be reproduced in whole or in part without prior written consent from
Toshiba America Consumer Products, Inc., Service Division.
Contents
Section 1
Video Signal Flow
1-1. Basic N5SS and N7SS Differences........................................3
1-2. Video Signal Flow..................................................................3
Section 2
Audio Signal Flow
2-1. Audio Signal Flow..................................................................7
Section 3
Power Supply
3-1. Outline of system................................................................10
3-2. Standby Power Supply.......................................................11
3-3. Main Supply........................................................................11
3-4. Outline of the Current Resonant Type Supply.................12
3-5. Fundamental Theory of LC Series Resonant Circuit......12
3-6. Main Supply Actual operation.........................................13
3-7. Scan derived voltages (FBT)..............................................17
3-8. Protector Module (Z801)...................................................18
3-9. Sub Supply..........................................................................19
Section 4
Shut Down Circuits
4-1. Summary of Shut down circuits.........................................21
4-2. Power shut down troubleshooting guide...........................23
4-2-1. +30 Volt Over Voltage Protect....................................................... 24
4-2-2. +15V Over Voltage Protect.............................................................24
4-2-3. +30 V Over Current Protect...........................................................25
4-2-4. +15V Over Current Protect............................................................25
4-2-5. -15V Over Current Protect.............................................................26
4-2-6. +35V Over Current Protect............................................................26
4-2-7. +/-15V Under Voltage Protect.........................................................27
4-2-8. 200V Under Voltage Protect...........................................................28
4-2-9. X-Ray (High Voltage) Protect.........................................................28
4-2-10. +125V Over Current Protect........................................................29
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Section 1
Video Signal Flow
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1-1.Basic N5SS and N7SS Differences
The basic operation of the standard aspect ratio, interlace scan N7SS version of the TG-1 chassis is similar to
the N5SS version. In the E - series N5SS, the microcomputer generated the OSD, but in the N7SS, the new
OSD board generates the On Screen Display, as well as
the EDS and Closed Captioning. The On Screen Display is now Icon based and much more user friendly.
Some Projection models include a component video
input, known as"Color Stream", for use with a DVD
player.
Dolby ProLogic audio and StarSight have been
removed from most models.
The power supplies are mostly the same as in the
N5SS. Some models contain a new version of the
main supply voltage control IC, Q801.
The Theater Wide models and the Progressive Scan
models are not addressed in this update.
Although this treatment focuses on the TP50G60, the
video and audio signal flow diagrams can be applied
to most standard, interlace scan TG-1 chassis.
1-2. Video Signal Flow
Figures 1and 2 illustrate the video signal flow through
the chassis. The Antenna 1 (ANT 1) and Antenna 2
(ANT 2) inputs allow two separate RF signals to be connected to the RF switcher. When the switch, controlled
by the microcomputer, QA01, is in the up position, the
ANT 1 signal is connected to the HY01 PIP Tuner/IF
and the H001 Main Tuner. Moving the switch down
connects the ANT 2 signal to the H001 Tuner. Due to
the RF Switch, the ANT 2 signal can’t be used as the
PIP source, but when ANT 2 is selected the ANT 1 signal is available at the RF OUT. The PIP Tuner/IF produces a composite video (CV) signal and sends it to the
AV Switcher , QV01. An IF signal produced by the Main
Tuner is sent to H002, which produces a composite video
signal and sends it to the AV Switcher.
A switch on the Cb jack of the video 2 input tells the
Switching IC, QV01, when a composit video input is
connected to video 2. This will will result in different
switching in the signal path.
When the input to video 2 is component video, the following path does NOT apply.
The selected video signal is output as composite video,
and sent to the video output jack, the New OSD Board,
and the Digital Comb Filter. After Y/C seperation, the
video signal is sent back to the AV Switcher as separate
luminance (Y) and chrominance (C) signals. The Y and
C signals are then sent to Q501, the Video Chroma Deflection Processing IC. Q501 processes the video signal and sends separate Y, I, and Q signals. The Y, I, and
Q signals are then sent to QW01, the Color Switch.
Component video from video 2 input can now be considered. The video 2Y, Cr, and Cb signals are also sent
to QW01. This circuit switches the video source for the
Y, I, and Q signals for the main picture input to Q501.
Q501 processes the selected signals into seperate R, G,
and B. The R, G, and B signals are sent to the CRT
drives and the CRTs.
If the PIP feature is selected, composite video from AV
Switcher is sent to the PIP circuit, ZY01. After processing, the PIP signal is sent to Q501 as R, G, B, and YS
where it is mixed with the main video. NOTE: When
component video is connected to video 2, video 2 can
not be used as a PIP source.
RGB signals from the digital convergence board are sent
to the Q501 via the PIP board, ZY01.
On screen display (OSD), Extended Data Service (EDS),
and Closed Caption (CC) data RGB is generated on the
New OSD board, UM01. These signals are applied to
Q501, where they are mixed with the main and PIP video
signals.
Three video inputs, video 1 through 3, are applied to the
AV Switcher . The video 1 input can be composite video,
Y/C video, or the test signal from QA01. Video 2 can
be composite video or component video, and video 3 is
either composite video or Y/C video. A mechanical
switch on the video 1 input defaults to the test signal, so
a video connector must not be plugged into the video 1
input jack when the internal test signals are to be used.
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Figure 1. Video Block A
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Figure 2. Video Block B
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Section 2
Audio Signal Flow
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2-1. Audio Signal Flow
Figure 3 illustrates the audio signal flow.
L and R Audio signals are applied to the AV Switcher
from the Video 1, 2, and 3 audio jacks, and the IF/MTS/
A. PRO IC, H002. There is no PIP tuner audio. Like
the video signal, there must not be a connector in video
1's audio jacks for the audio test signal to be applied to
the AV Switcher. The main audio signals are applied to
the audio output jacks and to the Front Surround circuit.
After processing, the left and right audio signals are applied to the audio processor in H002 where the volume,
balance, treble, and bass are controlled. Next, the audio
signals are amplified by QS101 and applied to the variable audio output jacks, and to power amplifier, Q601.
If the sub bass system (SBS) is selected, the signal is
mixed with the left and right signals just before Q601 to
increase the bass response.
In the TP50G90, TP55G60, and TP61G60/90models,
jumpersGJ01 and GJ02 are removed, and a center channel switch and audio jack are added to the rear connector panel. A center audio signal from an external source
can be connected here and switched in to replace the
main left and right signals to the internal speakers.
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Figure 3. Audio Block
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