ViewSonic P90F, P90f-1, VCDTS23483-1 Service Manual

Service Manual

ViewSonic P90f-1

Model No. VCDTS23483-1

19” Digital Controlled Color Monitor

(P90f_SM_525 - Rev. 1a – April 2002)

ViewSonic



381 Brea Canyon Road, Walnut, California 91789 USA - [phone]

ii

Copyright

Copyright



2002 by ViewSonic Corporation. All rights reserved. No part of this publication may be
reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language or
computer language, in any form or by any means, electronic, mechanical, magnetic, optical, chemical,
manual or otherwise, without the prior written permission of ViewSonic Corporation.

Disclaimer

ViewSonic makes no representations or warranties, either expressed or implied, with respect to the
contents hereof and specifically disclaims any warranty of merchantability or fitness for any particular
purpose. Further, ViewSonic reserves the right to revise this publication and to make changes from time
to time in the contents hereof without obligation of ViewSonic to notify any person of such revision or
changes.

Trademarks

ViewSonic is a registered trademark of ViewSonic Corporation.
All other trademarks used within this document are the property of their respective owners.

Revision History

Revision Date Description Of Changes Approval

1a 4/17/02 Initial Release DCN-2207 K.Yang

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TABLE OF CONTENTS

1.

PRECAUTIONS AND NOTICES...........................................................................1~2

2.

SPECIFICATIONS ....................................................................................................3

3.

TIMING CHART ........................................................................................................4

4.

CONTROL LOCATION AND FUNCTIONS ..........................................................5~8

5.

MECHANICAL PARTS & MECHANICAL ASSEMBLY......................................9~10

6

. CONNECTOR PIN ASSIGNMENTS.....

...................................................................11

7.

MONITOR INSTALLATION......................................................................................12

8.

ELECTRONIC CIRCUIT DESCRIPTION ..........................................................13~20

9.

ADJUSTMENT..................................................................................................21~27

10.

TROUBLESHOOTING FLOW CHART............................................................28~34

11.

REPLACEMENT PARTES LIST......................................................................35~57

12.

SCHEMATIC DIAGRAMS ...............................................................................58~61

13.

PCB LAYOUT..................................................................................................62~68

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1.

PRECAUTIONS AND NOTICES

1.1

SAFETY PRECAUTIONS

1) Observe all cautions and safety related notes located inside the display cabinet and on the
displaychassis.

2) Operation of this display outside the cabinet or with the cover removed, involves at shock
harzard from the display power supplies. Work on the display should not be attempted by anyone
who is not thoroughly familiar with precautions necessary when working on high voltage
equipement.

3) Do not install, remove or handle the picture tube in any manner unless shatter-proof goggles
are worn. People not so equiped should be kept away while handling picture tube.Keep picture
tube away from body while handling.

1.2 Observe all cautionary and safety related notes located on the chassis, cabinet and display tube.

1.3 Operation of the monitor with the back cover removed presents a potential shock hazard. Only

personnel familiar with the precautions necessary for safe working on high voltage equipment
should attempt to carry out servicing.

1.4

Always wear shatter proof goggles when removing, installing or generally handing the picture tube.
People not so equipped should be kept at a safe distance when any such handing is being
undertaken. Do not handle the picture tube by the neck of deflection coil. Do not carry the picture
tube resting against the body.

1.5

The picture tube is designed and constructed to limit X-Radiation to a safe level during normal
operation. To maintain the required level of protection and safe operation, replacement tubes
must be correctly adjusted and any protective circuits must not defeat.

1.6

IMPORTANT-Safety Tests

After servicing, and before returning the monitor to the user, a thorough safety test must be
carried out to ensure there is no potential shock hazard to any operator(s) using the monitor.
All the following test must be performed. A monitor failing any of these tests should be rejected
and have the problem rectified.

1.7

A.C. Leakage Test

Remove the power sourse. Connent the monitor to the circuir as in figure 1 below. Switch the
monitor on/off switch to on. A reading of less than 3.5mA should obtained (ref. EN60950).

Equipment safety
Earth terminal

Equipment
Under test

Measuring instrument

Isolating
transformer

L

N

Fig.1 Measurement of AC Leakage Current.

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1.8

Voltage Breakdown Test
Connent the live and neutral connections together. Switch the monitor on/off switch to on Apply
1500VAC RMS or 2250VDC, 50Hz for one minute between live and neutral shorted together and
earth. Ensure no voltage breakdown occurs.

1.9

Earth Resistance/Continuity Test

Measure the resistance between the signal cable metal shell and the earth pin in the A.C. socket.
At a current of 25 amperes the resistance should be less than 100m.
NOTE:A portable appliance tester (PAT) is a suitable instrument to use for the above safety tests.

1.10

H.V. Over Voltage Portection (Required for X-Radiation Safety)

Adjust R176 slowly anti-clockwise until the over voltage protection circuit is activated, and the high
voltage must be less than 33KV at this moment. After test, R176 should be adjusted back to
normal(=26.2KV)

CAPACITOR:

C850 400V 4700PFM CAPACITOR.CERAMIC 5230105501
C851 400V 4700PFM CAPACITOR.CERAMIC 5230105501
C135 250V 33UFM CAPACITOR.ELECTROLYTIC 5214433012
C139 100V 330UFM CAPACITOR.ELECTROLYTIC 5214019612

RESISTOR

R827 1K RESISTOR.VS 5162161020

SEMICONDUCTORS

I101, I803 UC3842N IC LINEAR 6644063111
I301 (RA) TDA9116 SDIP32 IC.LINEAR A.S.D.C. 6644076308
I301 (RB) TDA9113 SDTP-32 IC.LINEAR A.S.D.C. 6644076305
I310 TDA8172 7P IC.LINEAR 6644076000
IA01 NT68F62U IC.LSI MCU FLASH MTP 6647008204
Q801 2SK2648-01 TR FET MOS 6626003208
Q433 2SC5587AS TR NPN HF 6621040405
Q121 2SK2843 TR FET MOS 6626003203
D807 RD20EB2-T1 TR PNP HF. 6615011831
D827 HZ5C1 DIODE ZENER 6615007834

OTHERS

SR801 OSA-SS-212DM5 RELAY 5054613402
F801 250V/3.15A FUSE 5054431539
T801 TPW-697 POWER TRANSFORMER 5061369700
T101 TFB-280L TRAQNS.FLYBACK COLOR 5062628032
V901 (CA) M46QDG423X04 CCRT/DY 5051286325

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2.

SPECIFICATIONS

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Size and deflection angle 19 inch 90 degree
Screen type Flatron
Horizontal pitch / Dot pitch 0.24mm
Surface treatment Anti-static AR coating

CDT

Transmission rate 46%
Horizontal Frequency 30kHz to 110KHz

Scanning
Freq.

Vertical Frequency 50Hz to 180Hz
Video amplifier Applicable pixel rate 265MHz
Resolution

Maximum 1600 x 1200 @85Hz
Modes

Factory preset/User modes 12/ 14

AC input range 100 to 240 Vac

Max. power consumption

<130W

Suspend <4W

Power

Power Management

Off <4W

Power Switch On/off with Led indicator

Up/Down adjustment Key

2 key pads for adjust
Up / down keys are direct access for Contrast
And Brightness adjustment

“2” Key

As a select key/ go to next sub menu

User controls

Auto-size Key Auto-sizing

Signal

connections

Standard Model

1.8 m signal cable with 15Pin D shell miniature

male connector.

Rear

connection

Power input AC socket with 1.8 meter cable

Safety CB,BSM2,VPSB,C-TICT,TUV/S(Argentina)

Emissions EN50081-1

Immunity EN50082-1

ISO9241Paart3 &ISO9241Part8

Ergonomic

ZH1/618

VLMF MPRII

European

Safety UL1950
Emissions FCC class B

USA

X-ray DHHS
Safety EIAJ

Agency
Approvals

Japan

Emissions VCCI category 2

Plug and Play DDC 1/2 B Version 2

Operating Temperature

Storage Temperature

10°C to 40°C
–30°C to +60°C

Operating Humidity 10% to 90%

Environmental
Conditions

Storage Humidity 10% to 95 %

Dimensions W x H x D 475.8 mm x 492.1mm x470.7mm
Weight Kg 24.05Kg (Gross)

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3.

TIMING CHART

Mode 1~ 13 : Preset Mode

Mode 14,15,16: Only for H-size limitation and Auto-size

Mode NO.

1 2 3 4 5 6 7 8

Unit

Pixel Clock

25.175 25.175 30.24 56.25 78.75 80.0 94.5 135

MHz

Resolution

640x400 640x480 640x480 800x600 1024x768 1024x768 1024x768 1280x1024

Horizontal Frequency

31.469 31.469 35 53.674 60.023 60.241 68.677 79.976

KHz

(A) Horizontal Period

31.779 31.778 28.571 18.631 16.660 16.6 14.561 12.504

usec

(B) Horizontal Pulse
Width

3.813 3.813 2.116 1.138 1.219 1.2 1.016 1.067

usec

(C) Horizontal Back Porch

1.907 1.907 3.175 2.702 2.235 2.2 2.201 1.837

usec

(D) Horizontal Active Area

25.422 25.422 21.164 14.222 13.003 12.8 10.836 9.481

usec

(E) Horizontal Front Porch

0.637 0.636 2.116 0.569 0.203 0.4 0.508 0.119

usec

(F) H. Sync. Polarity

- - - + + - + +

Vertical Frequency

70.087 59.94 66.667 85.061 75.029 74.927 84.997 75.025

Hz

(O) Vertical Period

14.269 16.683 15 11.756 13.328 13.346 11.765 13.329

msec

(P) Vertical Pulse Width

0.064 0.064 0.086 0.056 0.050 0.050 0.044 0.038

msec

(Q) Vertical Back Porch

1.112 1.049 1.114 0.503 0.466 0.498 0.524 0.475

msec

(R) Vertical Active Area

12.712 15.253 13.714 11.179 12.795 12.749 11.183 12.804

msec

(S) Vertical Front Porch

0.381 0.317 0.086 0.018 0.017 0.049 0.014 0.012

msec

(T) V. Sync. Polarity

+ - - + + - + +

(U) Interlaced

No No No No No No No No

Mode NO.

9 10 11 12 13 14 15 16

Unit

Pixel Clock

157.5 202.5 229.5 261 57.28 40 49.5 36

MHz

Resolution

1280 x

1024

1600x1200 1600x1200 1792x1344 832x624 800x600 800x600 640x480

Horizontal Frequency

91.146 93.75 106.25 106.27 49.725 37.8 46.875 43.269

KHz

(A) Horizontal Period

10.971 10.667 9.412 9.41 20.111 26.4 21.333 23.111

usec

(B) Horizontal PulseWidth

1.016 0.948 0.837 0.828 1.117 3.2 1.616 1.556

usec

(C) Horizontal Back Porch

1.422 1.501 1.325 1.349 3.910 2.2 3.232 2.222

usec

(D) Horizontal Active Area

8.127 7.901 6.972 6.866 14.524 20 16.162 17.778

usec

(E) Horizontal FrontPorch

0.406 0.316 0.279 0.368 0.560 1 0.323 1.556

usec

(F) H. Sync. Polarity

+ + + - - + + +

Vertical Frequency

85.024 75 85 74.997 74.5 60 75 85.008

Hz

(O) Vertical Period

11.761 13.333 11.765 13.334 13.414 16.579 13.333 11.764

msec

(P) Vertical Pulse Width

0.033 0.032 0.028 0.028 0.060 0.106 0.064 0.069

msec

(Q) Vertical Back Porch

0.483 0.491 0.433 0.649 0.784 0.607 0.448 0.578

msec

(R) Vertical Active Area

11.235 12.8 11.294 12.647 12.549 15.84 12.8 11.093

msec

(S) Vertical Front Porch

0.011 0.011 0.009 0.009 0.021 0.017 0.021 0.023

msec

(T) V. Sync. Polarity

+ + + + - + + +

(U) Interlaced

No No No No No No No No

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4.

CONTROL LOCATION AND FUNCTIONS

Power S.W
Power Light

Auto Size

Select Key

OSD

ON/OFF

Down Key

Up Key

Front

15 Pin D Sub Video Cable

Power Cord

Rear

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Function Keys Description:

(a) Key function:

Power switch: This is a “software Key”, Turns the display on and off. The power indicator will lit “Green”
when the display is on.

“1” key: Turn on /off OSD menu / Exist this menu to go back previous menu.

: Down side to select item / decrease value.

: Up side to select item / increase value.

. keys are direct access for Contrast and Brightness adjustment.

(b) “2” key: a select key / go to next sub menu.

(c) Pressing “2” & power keys at same time will enter the factory optimized OSD Menu.

(d) Selected

∩

icon and then pressing “2” key will do demagnetize CDT, if pressing maintain to

more than 3 sec will de force MCU to enter burn in state for production line burning.

(e). Press key will auto adjust the display.

Factory OSD Menu

OSD menu descriptions:

Press “1” key to display a basic main menu (1) shown as below.

Using and keys to move a cyan window bar get your desired items. If it is selected, then pressing
“2” key to display Sub menu as below to start adjustment.

Use and to decrease / increase value on selected item. Noted that the menu can do two items
adjust pressing “2” change to another one in toggle.

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In main menu (1), selected “main menu (1) and then pressing up or down key to the top or bottom of
this menu, the next pressing will go to main menu(2) as below to others

FIGURE 2 ( USER MODE OSD MENU 2 )

In main menu 2, if selected “ VIEWMATCH COLOR”, then pressing “2” key will display color sub menu
as following.

The three default color modes such as 9300k, 6500k, 5000k only can be set in factory, means, they can
read and display only in this menu.

If selected “user color”, then pressing “2” key will display next sub menu as below to start color
adjustment.

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In main menu (2), if selected “LANGUAGE”, then pressing “2” key will display next sub menu as below
to language. Select as below:

If selected “view meter”, and then pressing “2” key will display next sub menu as below to show timing
information.

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5.

MECHANICAL PARTS & MECHANICAL ASSEMBLY

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P90f Mechanical Parts list

NO. DESCRIPTION PART NO. QTY

M1 FRONT COVER 5642286900 1
M2 BACK COVER 5642287000 1
M3 FUNCTION KEY 5642846000 1
M4 POWER LIGHT PIPE 5640328200 1
M5 POWER KEY 5642845900 1
M6 RUBBER WASHER 5642020001 4
M7 RING CABLE 5642655600 1
M8 LEFT BRACKET 5648734100 1

M9 SPRING FINGER 5648006000 2
M10 MAIN CHASSIS BRACKET 5648734300 1
M11 RIGHT BRACKET 5648734200 1
M12 REAR BRACKET 5648734400 1
M13 PCB SPACER SUPPORT 5642670400 3
M14 SWIVEL WASHER 5642722300 1
M15 SWIVEL CLAMP 5642676500 1
M16 SWIVEL 5641410300 1
M17 BASE 5641410400 1
M18 FOOT PAD 5642022700 4

S1 SCREW BTBW M3X10 7000305022 4
S2 SCREW PHB+CW+RW M5X24 7190561001 4
S3 SCREW PZP M4X14 7134251982 7
S4 SCREW BTBW M3X8 7000305012 16
S5 SCREW PZP M4X16 7134252282 4
S6 SCREW PZP M4X20 7190562424 1

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6.

CONNECTOR PIN ASSIGNMENTS

6-1 The Pin-assignments of the 15pin D-sub male miniature connector are shown
below:

6-2 15 Pin Min D-sub male connector

PIN NO PIN DESCRIPTION

1 RED

2 GREEN

3 BLUE

4 NO CONNECTION

5 GROUND

6 R-GROUND

7 G-GROUND

8 B-GROUND

9 +5V PC97

10 GROUND

11 NO CONNECTION

12 SDA FOR DDC

13 H.SYNC.

14 V.SYNC.

15 SCL FOR DDC

1

6

11

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7.

MONITOR INSTALLATION

Monitor Installation

How to Install the Connections to your PC

7-1. Your monitor has two connection cables:

.A signal cable which connects to your computer's VGA connector. Which is colored blue.

7-2. To ensure your safety when connecting the cable, always follow these six steps:

(Ⅰ). Turn off the power to your computer and peripheral equipment.
(Ⅱ). Position the monitor and computer so that you can easily access the rear panel of each unit.
(Ⅲ). Connect the blue-colored video signal cable D-sub connector to the signal connector on the

graphics board (VGA connector) on your computer. (See your system user's guide for the
exact location of your VGA connector.)

(Ⅳ).Tighten the screws on the signal cable connector to prevent it from coming loose, and to

prevent radio and TV interference.

(Ⅴ).There are two kinds of Power Cord, one is to connect between your monitor and the wall

outlet, the other type is to connect between your monitor and PC.

- You might have either of the above two type of power cord. To connect the power cord
between monitor and PC, you have to plug one-end of the power cord to the monitor
power input socket, and plug the other end of the power cord to the PC power output
feed.

- To connect Power Cord between your monitor and wall outlet , you have to connect the
power cord to the monitor power input socket on back of the monitor .Plug the other ent
of the power cord into your surge protector or properly-grounded electrical outlet

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8.

ELECTRONIC CIRCUIT DESCRIPTION

8-1 SWTCHING MODE POWER SUPPLY SECTION

8-1-1 Features

1. AC input: 100Vac – 240Vac.

2. When Power Saving activated, change feedback to reduce the output voltage and shut down
timebase and video circuit operation, thus power reduce to be less than 5W.

8-1-2 Circuit description:

8-1-2-1 EMI Noise Filter

8-1-2-2 C802 and C803 build as Y capacitors, C804 is X capacitor, L801 and L802 are Common

Mode Choke, those build as a two steps Noise filter.

8-1-2-3 Power supply activation:

The rectified voltage across C809 charge C815 through R809, R810, R811, R812, Q810,
and D822, When UC3842 pin 7 rise up to 14V, Q816 on and Q810 off. C817 charge to
55Vdc, this voltage is ready for B+ of UC3842at Pin7 during Suspend, or Off Mode( > 10V).
C844 also provides a voltage for UVP (Vac under voltage protection). When C844 voltage is
too low, Q814 turns off, voltage at pin 2 of UC3842 is over 2.5Vdc, UC3842 will be turned off
and protected.

8-1-2-4 Degaussing circuit

Degaussing coil is connected to relay (SR801), and controlled by MCU through Q856 Q857,
When power is turned on, SR801 close, and automatic demagnetization operate for a few
seconds, then SR801 open. Degaussing also can be operated by pressing degaussing key
on the front bezel.

8-1-2-5 UC3842 PWM controller

UC3842 is a current feedback PWM controller:
Pin1---is feedback positive end.
Pin2---190V and 9V at secondary side of power transformer provide a sampling

voltage to pin 2 of UC3842 via I808, I807.

Pin3---is a current feedback input, when it is over 1V, no output at pin6 to drive

output stage.

Pin4---This pin determine the operating frequency which is trig by a sync. signal

coming from I810.

Pin6---this output drive power MOSFET (Q801).

8-1-2-6 Output voltage feedback control theory

Feedback control is sampled from 190Vdc and 9Vdc at secondary side, through VR R827

2.5V feedback to reference pin of I808( R ), then I 807 coupled to pin 2 of UC3842. When
output voltage rise up, I 808 Reference voltage(R) rise up too, Cathode( K) voltage goes
down. More conduction on I807 in turns cause voltage across R826 to rise. UC3842 pin2
voltage rise to reduce the duty at output pin6. Q801 conduct less to reduce the secondary
side voltages, thus to stabilize the DC voltages at secondary side.

8-1-2-7 Over-voltage protection

When output voltage are too High, voltage across C817 will be high and voltage drop on
R872 is also high. It will force Q808, Q807 to conduct and pin8 of UC3842 to ground. Thus
UC3842 stop to operate.

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8-1-2-8 Under-voltage protection

If Ac input voltage is too low, voltage across C844 will be too low that force Q814 to turn off
and voltage across C822 rise up. When pin2 of UC3842 rise up to 2.5V, pin6 stop to drive
output. Thus Q801 is protected.

8-1-2-9 Synchronization circuit

UC3842 working frequency is fixed at 33.3 Khz by adjusting R817A.

8-1-2-10 Power Saving control

At normal operating state, Q811 on, Q812 off, output voltage are normal. At stand-by or
suspend Mode, Q811 off, Q812 on, feedback voltage increase to reduce output voltages
down to 1/3 of normal approx.. If enter off Mode, Q811 and Q812 Off, feedback voltage
increase more to reduce output voltages down to
1/4 of normal. And the another great frequency control is to connect R821 to set power
supply working at low frequency about 10 Khz. By above two ways, it can meet DPMS and
NUTEK requirement.
When monitor enter power saving state, voltage across C817 controlled by I804, Q815
continue to supply pin 7 of UC3842 to operate and voltage across C811 controlled by
Q805,Q806 continue to supply 5V for IA01 to stand by.

8-2 DIGITAL CONTROL CIRCUIT( Signal control by Microprocessor unit; IA01)

Horizontal and vertical sync. signal coming from CRT drive Board(PWB—0237)are fed into

pin41(H. sync.) and pin42(V. sync.) of IA01.When the power cord plug in, pin4 of IA01 reset

and IA01 start to check if the sync. Signals are exist at pin 41 and pin 42. The control tables

are as follows:

Power state Normal Standby/suspend Off

Pin42,Pin41 V sync. H. sync. V or H. sync. exist Both sync. not exist

Pin23

Logic high Logic low Logic low

I804 ON OFF OFF

Pin24(G) High High Low

Pin22(A) Low High High

LED Green Yellow Amber

Standby/suspend Mode:

If only one of the sync signal exist, pin23 of IA01 change to low and turns off Q811 and pin21 of

IA01 change to high and turns on Q812. The feedback will be reduced through I808 and cut

down all the secondary output voltages. In order to maintain the supply voltage for I803 PWM,

I804 is then turned on, Q815 turns on too. The supply voltage from D812 is then connected to

Vcc of I803. The off signal from pin23 of IA01 also turns Q805, Q806 on, the supply voltage at

input of I802 is then taken from D804 to keep 5V for IA01 continue working. In order to keep

stand-by voltage for CRT heater, Q867 continue to conduct by the logic from pin21 of IA01.

Off mode:

When both sync. Signals are absent, IA01 will send a logic. Low at pin 23 and pin21 to turn

Q811, Q812 off. The secondary voltages will be reduced further, and Q867, Q866 are turned

off. The heater voltage become zero for further lower power consumption than stand-

by/suspend Mode.

Normal Power supply operation:

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When the sync signals are both exist, then IA01 will send Low at pin 13 to switch on the relay

BR801 via Q104 and Q104A and thus produce a very high current circulate the degaussing coil

and this signal will sustain for a certain period. Thus the display is demagnetized

The sync signals are buffered by IA01 and output at pin 41, 42 to synchronize the timebase

controller I301. IA01 will also initiate I301 by IIC bus build by pin 28(C.SCL), pin 27(C.SDA).

This IIC bus is also responsible to initiate the video pre-amplifier I901and OSD I903. After the

initiation is completed I301, I901 and I903 will operate normally. This IIC bus also provides

Purity control, through P421, connect to PWB-0417, purity control board.

Pin 17 to pin 20 and pin32 provide the logic to control the horizontal CS linear correction circuit

according to the horizontal frequency range as the following table.

P90f CS Table

CS

CS4 CS3 CS2 CS1 CS0

MCU Pin 32 17 18 19 20

Capacitor C425 C421 C420 C419 C423

Hf <32KHz H H H H H

32KHz<Hf<=36KHz H H L H L

36KHz<Hf<=40KHz H H L L L

40KHz<Hf<=45KHz L H H H H

45KHz<Hf<=52KHz L L H L H

52KHz<Hf<=58KHz L L H L L

58KHz<Hf<=65KHz L H L H H

65KHz<Hf<=70KHz L L L H L

70KHz<Hf<=86KHz L H L L H

86KHz<Hf<=96KHz L H L L L

Hf>96KHz L L L L L

Pin 36 (F/V) provides horizontal C linearity control.

Pin 40 provide rotation PWM to rotation circuit build by Q701, Q702 and Q703 and thus control

the current circulate the coil around the deflection yoke to rotate the display.

Pin 1 provide Horizontal convergence control through Q426,Q427, Q428.

Pin39 provide Vertical convergence control through Q305, Q306, Q307.

Pin 31 short to ground via 15pin D sub connector when it connect to PC. When it is

disconnected, power saving feature is switch off, monitor will display “NO SIGNAL” as self test

pattern.

IA02 is E

2

PROM for IA01 to save settings of all modes and DDC data.

8-3 TIMEBASE CIRCUIT

8-3-1 TIMEBASE CONTROL (I301), HORIZONTAL

I301 is an IIC control Time-base processor, By IIC bus pin30, 31(SDA,SCL) it can communicate

with IA01(MCU)

HS

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H. sync., V. sync feed from IA01 pin41,42 to I301 pin1 ,2. When the H. Freq. is over 110kHz or

below 30kHz, I301 will shut down to protect the Horizon. output CKT from being damaged. The

Horizon. oscillator is build by C303 and R301 and determine the Horizon. frequency range.

C304, C305, R302 build up PLL 1 loop filter,

Via Icon, the IIC-bus allows a linear adjustment of the Horizon. position by comparing

relative phase of horizontal Sync. and oscillator saw-tooth(in PLL 1 loop) and feedback from

Horizon. output stage.

and correction of pin unbalance and parallelogram are done by modulating the

phase between oscillator saw-tooth and horizontal. flyback (in loop PLL2)

The PLL2 phase detector is similar to PLL 1 detector and compares the Horizon. flyback pulse

at pin 12 with the oscillator saw-tooth wave-form. The controlled currents are independent of

Horizon. freq. The PLL 2 thus compensates for the delay in the output horizontal deflection CKT

by adjusting the phase of the HDRV (pin26) output pulse.

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17

8-3-2 HORIZONTAL OUTPUT STAGE

The horizon. drive pulse output at pin 26 is pulled up to 12V to drive Q404 and then coupled via

T401 to output transistor Q403 for on-off control. Thus saw-tooth current flow through Horizon.

Deflection Yoke is obtained.

The function of C-correction is to correct the asymmetrical non-linearity of picture. L402, L406

and Horizontal Yoke are in series for C-correction. Pin36 of IA01 provides a voltage which

depends on Horizontal frequency to control L402 via Q405, thus the inductance of L402

changes according to the Horizontal frequency to correct the linearity.

The function of S-correction is to correct the symmetrical non-linear distortion equidistant lines.

C416, C423, C419, C420, C421, C425 are S-correction capacitors, also they block the DC

voltage to the Yoke. C416 is the fixed one, the others are controlled by IA01 via Q417, Q411,

Q413, Q415, and Q418 switches. When any switch turns on, the accordingly capacitor is in

parallel with C416. The switches on-off depend on the Horizontal Frequency.

L406 is controlled by pin32 as well, when Horizon. freq. is over 40kHz , L406 is parallel with

L402.

They are:

CS

CS4 CS3 CS2 CS1 CS0

MCU Pin 32 17 18 19 20

Capacitor C425 L406 C421 C420 C419 C423

Hf <32KHz ON OFF ON ON ON ON

32KHz<Hf<=36KHz ON OFF ON OFF ON OFF

36KHz<Hf<=40KHz ON OFF ON OFF OFF OFF

40KHz<Hf<=45KHz OFF ON ON ON ON ON

45KHz<Hf<=52KHz OFF ON OFF ON OFF ON

52KHz<Hf<=58KHz OFF ON OFF ON OFF OFF

58KHz<Hf<=65KHz OFF ON ON OFF ON ON

65KHz<Hf<=70KHz OFF ON OFF OFF ON OFF

70KHz<Hf<=86KHz OFF ON ON OFF OFF ON

86KHz<Hf<=96KHz OFF ON ON OFF OFF OFF

Hf>96KHz OFF ON OFF OFF OFF OFF

8-3-3 SUPPLY VOLTAGE CONTROL FOR HORIZONTAL DEFLECTION

The B+ control function block is included in I301 which consists of an operational Trans-

conductance amplifier, a voltage comparator, a flip-flop and a discharge circuit. Pin 28 of I301

is a drive voltage which consists of horizontal width, pincushion, and trapezium and pin-corner

correction. This voltage is controlled by IA01 via IIC bus. The drive voltage feed into pin 15

(BIN) of I301. The operation frequency of the B+ control block is the same as horizontal

frequency. The B+ drive output of the control block is at pin 28(BDRV), this drive voltage

switch Q402 on-off via a buffer build by Q400 and Q401. Q402, act as an step down DC

Rf

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