Philips B8 Series 7562, HC9719 Schematic

Color Television Chassis

Service Service Service

Contents

5. Service Modes, Error Codes and Faultfinding

6. Block Diagrams and Testpoints

7. Electrical Diagrams and PWB's B8 CHASSIS TABLE OF SCHEMATIC DIAGRAMS MAIN CHASSIS (SECTION 1 OF 5) MAIN CHASSIS (SECTION 2 OF 5) MAIN CHASSIS (SECTION 3 OF 5) MAIN CHASSIS (SECTION 4 OF 5) MAIN CHASSIS (SECTION 5 OF 5 ) CRT PANEL (13", 19", & 20") CRT PANEL (25" & 27") KEYBOARD/SOUND SHAPER PANEL STEREO PANEL SCHEMATIC OCV TV PANEL SCHEMATIC CARD INTERCONNECT PANEL HEALTH CARE JACK PANEL LODGING/SMART PORT PANEL MAIN CHASSIS PCB (TOP) MAIN CHASSIS PCB (BOTTOM) 13", 19", & 20" CRT PANEL PCB 25", & 27" CRT PANEL PCB KEYBOARD/SOUND SHAPER PCB STEREO PANEL PCB OCV TV PANEL PCB (TOP) OCV TV PANEL PCB (BOTTOM) CARD INTERCONNECT PANEL PCB HEALTH CARE JACK PANEL PCB LODGING/SMART PORT PANEL PCB

8. Adjustments

10. Spare Parts List

B8 Series Chasssis

Manual 7562

Copyright 2001 Philips Consumer Electronics B.V. Eindhoven, The Netherlands. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by means, electronic, mechanical, photographic, or otherwise without the prior permission of Philips.

Published by Philips Consumer Electronics Subject to modification 2005 Aug 24

20B8(7562)

1 3 Vp-p 50 uSec

4.9 Vp-p 20 uSec

3.2 Vp-p 20 uSec

6 50 Vp-p 5 mSec

3 1 Vp-p 20 uSec

7 800 mVp-p 5 mSec

5.6 Vp-p 5 mSec

2.7 Vp-p 5 mSec

9 400 mVp-p 5 mSec

2.2 Vp-p 20 uSec

10 29 Vp-p 5 mSec

2.2 Vp-p 20 uSec

1.5 Vp-p 5 mSec

3.5 Vp-p 20 uSec

2.2 Vp-p 20 uSec

3.6 Vp-p 5 mSec

17 450 mVp-p 5 mSec

18 750 mVp-p 5 mSec

19 5 Vp-p 20 uSec

4.2 Vp-p 20 uSec

20B8(7562)

1.2 Vp-p 20 uSec

22 220 mVp-p

0.5 uSec

1.4 Vp-p 20 uSec

1.2 Vp-p 20 uSec

2.5 Vp-p 20 uSec

1.2 Vp-p 20 uSec

28 1 Vp-p 20 uSec

1.4 Vp-p 20 uSec

33 120 Vp-p 20 uSec

2.5 Vp-p 20 uSec

34 1040 Vp-p(a) 20 uSec

2.5 Vp-p 20 uSec

35 1 Vp-p 20 uSec

1.6 Vp-p 20 uSec

1.8 Vp-p 20 uSec

37 2 Vp-p 20 uSec

38 110 Vp-p 20 uSec

39 110 Vp-p 20 uSec

40 850 mVp-p 5 mSec

20B8(7562)

41 110 Vp-p 20 uSec

B8 COLOR TV CHASSIS OVERVIEW

The B8 Series Chassis is the Statement (standard line) TV Set produced by Philips Consumer Electronics Company for the 1997 model year. The B8 Chassis is used in TV Sets with 25, and 27 inch CRT's. The B8 Chassis is also used in Commercial TV Sets with 13, 19, 20, 25, and 27 inch CRT's. The chassis orientation is front to rear in the B8 design (sometimes called "NorthSouth"), because the chassis is longer in this direction than across. The B8 Tuning System features 181 Channels with On-Screen Display. The main Tuning System includes the tuner along with the Microcomputer IC and the Memory IC. The Microcomputer communicates with the Memory IC, the Customer Keyboard, the Remote Receiver, the U/V Tuner, the TV Signal Processor, the Stereo Decoder (optional), and the Power On/Off circuitry. The Memory IC retains the settings for Favorite Stations, Customer Control Settings, Mode Switches, and Service/Factory Setup Data.

The chassis features a Very Large Scale Integration (VLSI) IC for TV signal processing. This IC performs Video IF, Sound IF, AGC control, Horizontal Signal processing, Vertical Signal processing, Horizontal/Vertical synchronization, and Chrominance/Luminance p rocessing. The On-Screen Graphics information is placed on the main signal within the TV Signal Processor. OnScreen Graphics generation and Closed Caption decoding are processed within the Microcomputer and the signals are sent to the TV Signal Processor. Automatic Volume Level (AVL - called "SMART SOUND" by marketing) control from the Microcomputer is sent to the AVL IC. The "Smart Sound" function is performed within IC720.

The B8 Chassis features a Switching Mode Power Supply for the main voltage source. A "HOT" ground reference is used in the primary side of the power supply. A "COLD" (signal) ground from the secondary of the power supply is used throughout the rest of the chassis. AN ISOLATION TRANSFORMER IS REQUIRED WHEN DOING SERVICE ON ANY VERSION OF THE NEW CHASSIS.

SIGNAL FLOW

The incoming TV RF signal is applied to the U/V Tuner via the Antenna RF Input. The IF signal is developed within the U/V Tuner, then amplified by an IF Preamplifier located inside the Tuner. The amplified IF signal is sent from Pin 11 of the U/V Tuner to the SAW Filter, Y200. The SAW Filter produces bandpass shaping for the IF signal before it is applied to the TV Signal Processor Integrated Circuit, IC271, for processing. AGC (to the Tuner) and AFT (to the Microcomputer) signals are developed within IC271 and then sent to the Tuning System for RF Amp gain control.

Sound IF signal processing for the B8 Chassis is performed by coupling the 4.5MHz Sound IF signal from IC271, Pin 6, via a Buffer Amplifier, Q221, and 4.5MHz Band Pass Filter, Y220, into IC271, Pin 1. Audio is output from Pin 15 in mono versions and applied to the Audio Amp Output IC, IC730, to drive the speakers. For the stereo equipped sets, the detected baseband audio signal exits IC271, Pin 15, and then enters the Stereo Decoder IC200. The Stereo Decoder has Internal/External switching, via the control input on Pin 21, to allow either the detected baseband audio or External Audio from another source to be routed through and exit to IC730 and IC740.

Composite video from IC271, Pin 6, is buffered by Q221 and then passed through a 4.5MHz Trap, Y221, to remove any sound products present. This signal is buffered again by Q225 before it goes back to IC271, Pin 13. Depending on the part number of IC271, either BS315 or BS316 will be installed. With BS315 installed, The CC Video comes from Q225. If BS316 is installed, the CC Video comes from Pin 38 of IC271. Internal/External switching of the video is done within IC271. The chroma and luminance signals are then processed by the Chroma/Luminance Process block within IC271. Sync input from the Chroma/Luminance block to the

Horizontal/Vertical Processing block is applied internally within IC271.

Brightness, Picture, Sharpness, Color, and Tint control voltages are applied to IC271 from Microcomputer, IC300 via the IIC Bus. The Red, Green, and Blue signals are developed within IC271 and output via Pins 21, 20, and 19. The Black Current Level Set is Output from Pin 18. The Red, Green, and Blue video signals from IC271 are applied to the CRT Board. On the CRT Board, these signals are amplified before being applied to the CRT. The Drive and Cutoff controls for CRT Set-Up are controlled by the microprocessor via the IIC Bus using the Service Test Mode.

Horizontal and Vertical signals are also developed within IC27 1. Adjustments for Horizontal Centering, Vertical Centering, and Vertical Height are accomplished with the Remote Transmitter via the Service Test Mode. There is no adjustment for the Horizontal Oscillator. The horizontal circuit is a count down type of system that gets its base frequency from the 3.58MHz circuit.

The horizontal signal is applied to a Horizontal Driver, Q502, where the signal is amplified and transformer coupled to the Horizontal Output transistor, Q503. The output from Q503 drives the Integrated Flyback Transformer. The IFT develops the High Voltage, Screen Voltage, Focus Voltage, and Filament Voltage for the Picture Tube. If the voltage in T501 (T502 for 25 and 27 inch sets) goes high, a sample is sent to Q540 and Q541, the shutdown switch. This will enable lowering the High Voltage when it starts to elevate. Scan derived voltages provided by the IFT for use by the chassis are the 200V, +1 3.5V, and -13.5V Sources. A horizontal pulse is also made available for the chassis from the output circuit of the Horizontal Output transistor.

The Vertical signal exits TC271 at Pin 7 and is applied to the Vertical Output Integrated Circuit, IC550. The vertical signal is output from IC550 and applied to the Vertical Yoke. Vertical Centering and Vertical Height adjustments are performed via the Service Test Mode and Rem ote Transmitter. Vertical feedback is returned to IC550, Pin 1.

B8 CHASSIS POWER SUPPLY BLOCK

When a 120Vac Source is connected to the B8 Chassis, approximately I60Vdc is developed by

the Bridge Rectifier circuit. The 160 volts dc goes through T425 to the transistor switch. The start up signal is taken from the neutral leg of the input ac line.

The Power Supply consists of a single integrated circuit operating as a Free-Running Switching Mode Power Supply. The frequency of operation varies with the circuit load. There is no separate power supply for standby. The Power Supply turns On when AC is applied. The Switching Regulator IC starts switching when the initial voltage is applied through the Start circuit. The Switching Regulator and the Drive circuits turns the Switch On and Off to allow current flow through the primary of transformer T425. Energy stored in the primary during the On-time is delivered to the secondaries during the Off-time. Feedback from the Hot seco ndary is used to control the Switching Regulator. Positive Voltage from the hot secondary is used as B+ for the Switching Regulator.

From the secondaries of T425, the voltages needed to operate the television are developed. The Plus 9 volt output is switched for On/Off control.

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