ViewSonic N1750w SERIES Service Manual

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LCD TV MONITOR

N1750w SERIES

THESE DOCUMENTS ARE FOR REPAIR SERVICE INFORMATION ONLY. EVERY REASONABLE
EFFORT HAS BEEN MADE TO ENSURE THE ACCURACY OF THIS MANUAL; WE CANNOT
GUARANTEE THE ACCURACY OF THIS INFORMATION AFTER THE DATE OF PUBLICATION AND
DISCLAIMS RELIABILITY FOR CHANGES, ERRORS OR OMISSIONS.

MANUFACTURE DATA: Jan-30-2005

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Preface

Copyright © ViewSonic Corporation, 2004. All rights reserved.

Macintosh and Power Macintosh are registered trademarks of Apple Computer, Inc.

Microsoft, Windows, Windows NT, and the Windows logo are registered trademarks of Microsoft Corporation in the United
States and other countries.

ViewSonic, the three birds logo, OnView, ViewMatch, and ViewMeter are registered trademarks of ViewSonic Corporation.

VESA is a registered trademark of the Video Electronics Standards Association. DPMS and DDC are trademarks of VESA.

Disclaimer: ViewSonic Corporation shall not be liable for technical, editorial errors, or omissions contained herein; nor for
incidental or consequential damages resulting from furnishing this material, or the performance or use of this product.

In the interest of continuing product improvement, ViewSonic Corporation reserves the right to change product specifications
without notice. Information in this document may change without notice. For the most recent version of this document, please check
www.viewsonic.com.

No part of this document may be copied, reproduced, or transmitted by any means, for any purpose without prior written permission
from ViewSonic Corporation.

Important safety information

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with a dry cloth.

7. Do not block any of the ventilation openings. Install in accordance with the manufacturers instructions.

8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce

heat.

9. Do not defeat the safety purpose of the polarized or grounding type plug. A polarized plug has two blades with one wider than the

other. A grounding type plug has two blades and third grounding prong. The wide blade or third prong is provided for your safety.

When the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet.

10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they

exit from the apparatus.

11. Only use attachments/accessories specified by the manufacturer.

12. Use only with a cart, stand, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. When a cart is used,

use caution when moving the cart/apparatus combination to avoid injury from tip-over.

13. The TV should be operated only from the type of power source indicated on the label. If you are not sure of the type of power

supplied to your home, consult your dealer or local power company.

14. Unplug this apparatus during lightning storms or when unused for long periods of time.

15. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way, such

as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into apparatus, the apparatus has been

exposed to rain or moisture, does not operate normally, or has been dropped.

16. This product may contain lead or mercury. Disposal of these materials may be regulated due to environmental considerations.

For disposal or recycling information, please contact your local authorities or the Electronic Industries Alliance: www.eiae.org

17. Damage Requiring Service – The appliance should be serviced by qualified service personnel when:

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A. The power supply cord or the plug has been damaged; or

B. Objects have fallen, or liquid has been spilled into the appliance; or

C. The appliance has been exposed to rain; or

D. The appliance does not appear to operate normally or exhibits a marked change in performance; or

E. The appliance has been dropped, or the enclosure damaged.

18. Tilt/Stability – All televisions must comply with recommended international global safety standards for tilt and stability

properties of its cabinets design.

! Do not compromise these design standards by applying excessive pull force to the front,

or top, of the cabinet, which could ultimately overturn the product.

! Also, do not endanger yourself, or children, by placing electronic equipment/toys on the top of the cabinet. Such items could

unsuspectingly fall from the top of the set and cause product damage and/or personal injury.

19. Wall or Ceiling Mounting – The appliance should be mounted to a wall or ceiling only as recommended by the manufacturer.

20. Power Lines – An outdoor antenna should be located away from power lines.

21. Outdoor Antenna Grounding – If an outside antenna is connected to the receiver, be sure the antenna system is grounded so as

to provide some protection against voltage surges and built up static charges. Section 810 of the National Electric Cord,

ANSI/NFPA No. 70-1984, provides information with respect to proper grounding of the mats and supporting structure grounding

of the lead-in wire to an antenna-discharge unit, size of grounding connectors, location of antenna-discharge unit, connection to

grounding electrodes and requirements for the grounding electrode. See Figure below.

22. Objects and Liquid Entry – Care should be taken so that objects do not fall and liquids are not spilled into the enclosure

through openings.

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Table of contents

Table of contents …………………………………………………………………………………… 4
Revision list…………………………………………………………………………………….…. 5

1. Specifications …...............................................................................................…………...…..

6

1.1 General specifications ….......................................................................…………....…. 6

1.2 LCD TV description ..................................................……………….……...………….. 7

1.3 Interface connector ......................................................……………………….….....…. 7

1.4 D-Sub pin distribution ...............................................................…………...………….. 7

1.5 Factory preset display modes ....................................…………………………….....…. 8

2. Theory of operation.................................................................……………...…………………. 8

2.1 Video.............................………...................................................................………….... 8

2.2 Audio ...........................................................................................................………….... 9

2.3 Electrical .......................................................................................................…………... 9

3. Adjustment............................................................................................................…………..... 10

3.1 Front panel adjustment………………………………………………….……………… 10

3.2 How to use the menu…………………………………………………………………… 10

4. Assembly and disassembly procedure....................................................................…………..... 12

4.1 Disassembly .……………………………………………………………...……………. 12

5. Explode view…………………………………………………………………………………... 15

6. PCB layout……………………………………………………………………………………... 16

6.1 Main board…………………………………………………….……….……………… 16

6.2 Power board………………………………………………………………….………… 17

7. Main board IC descriptions……………………………………………………………………. 18

7.1 SPV302A…………………………………………………….……….………………… 18

7.1.1 General description ………………………………………………………………… 18

7.1.2 Block diagram ……………………………………………………………………… 18

7.1.3 List of pins and package …………………………………………………………… 19

7.1.4 IO-Trap ……………………………………………………………………………. 26

7.2 AD9883………………………………………………………………….………..…… 27

7.2.1 Description ………………………………………………………………………… 27

7.2.2 Block diagram ……………………………………………………………………… 27

7.3 VPC3230D.……………………………………….….………………………….…….. 28

7.3.1 Description ………………………………………………………………………… 28

7.3.2 Block diagram ……………………………………………………………………… 28

7.3.3 Pin functions …………………………………………….………………………… 28

7.4 UPD64083………………………………………..…………………………………….. 30

7.4.1 Description ………………………………………………………………………… 30

7.4.2 Block diagram ……………………………………………………………………… 30

7.5 TDA7266D..…………..………………………………………………………………...

31

7.5.1 Description ………………………………………………………………………… 31

7.5.2 Block diagram ……………………………………………………………………… 31

8. Block diagram ........................................................…………………………………….……...

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9. Schematic diagram ….......................................................................………………….………..

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9.1 Main board………………………………………………………………….………….

33

9.2 Power board………………………………………………………………….…………

47

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Revision list

Revision Date Modification Description

A00 Jan-30-05 Initial Release

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1. Specifications

1.1 General specifications

Item Specification

Screen Size 17” TFT-LCD Panel

Aspect Ratio 15:9

Resolution 1280×768 (WXGA)

Display Area 372mm×223mm

Pixel Pitch 0.291mm×0.291mm
Display colors 16.7 million
Contrast Ratio 600:1

Brightness 450cd/m2

Viewing Angle 170 (Horizontal)/170 (Vertical)
Response Time 12ms

Lamp Type/Life 50,000hr

LCD Panel

Color Temperature Cool/Warm
TV Tuning System NTSC 181 Channel with Electronic PLL Tuner

Sound System MTS/SAP

Closed Caption, V-chip Yes

TV Function

Color System NTSC

AV1 RCA×1 Audio L/R×1

RCA×1

AV2

S-Video RCA×1

Audio L/R×1(Share) Video Inputs

Component YPbPr×1 Audio L/R×1

Signal Input Analog: D-Sub 15 pin (detachable cable)

PnP compatibility DDC 2B

Input frequency Analog: FH: 31.5KHz to 61KHz FV: 56Hz to 75Hz

Recommended Analog: 1280 x 768 (60Hz)

PC Input

Input Audio Headphone Mini-jack for stereo (3.5ø)

Speaker (built-in): Two 5 watt speakers

Headphone Mini-jack for stereo (3.5ø)

Audio Output Audio Output: L / R

Line Output (RCA L/R)

Power Supply AC100V~120V, 50/60Hz

Power

Power Consumption <70W

Operating Temp. + 0°C ~ + 40°C

Storage Temp. - 25°C ~ + 60°C

Environment

Operating Humidity. 10 % ~ 85 %

Panel Tilt Forwards/Backwards/ Rotation -4° / +18° / ±25°

Dimension W x H x D (with stand) 560 x 340 x 233 (mm)

Weight (net) Kg (w/o Accessories) 6.8 Kg

OSD language English / French / Spanish

Table Stand Included
Wall Mount VESA 100 x 100 mm

Accessories

Remote Controller, Batteries (x2), AC Power Cord, D-sub Signal Cable, Audio line, User’s
Manual, QSG

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1.2 LCD TV description

The LCD TV will contain a main board (include audio), a switching power board (include an inverter board), an IR board and
a function keyboard. The main board and power board will house the flat panel to control logic I

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C bus, DDC, brightness
control logic for LCD panel, DC-DC conversion to supply the appropriate power to the whole board and transmitting TTL
level signals into LCD Module to drive the LCD display circuit.

The inverter board will drive the 6 CCFLs (Cold Cathode Fluorescent Tube).
The function keyboard and Remote Control will provide the OSD control signal to the Main Board.

1.3 Interface connector

All signal connections to this product are via external connectors locating at the rear of the product. The specifications of these
connectors are listed in the following table.

External Connector Specification

AC-In AC Jack 3-male receptacle

RGB Input

Molded-over, shielded, 15-pin subminiature D male plug with75Ω impedance.

Compliance with PC 99 Color Theme. Refer to Appendix B for pin layout.
Audio Input (L/R) RCA Jack (White/Red)
Audio Input 3.5 Mini Jack for PC Audio
Audio Output (R/L) RCA Jack (Red / White)
Headphone Output 3.5 Mini Jack
Composite Video RCA Jack (Yellow)
Component Video RCA jack (Red, Blue, Green)
S Video 4 Din Jack

1.4 D-Sub pin distribution

Connect the 15-pin color display shielded signal cable to your signal system device and lock both screws on the connector to
ensure firm grounding. The connector information is as follow:

15 - Pin Color Display Signal Cable

PIN NO. DESCRIPTION PIN NO. DESCRIPTION

1. RED Video 9. NC

2. GREEN Video 10. Sync Ground

3. BLUE Video 11. RXD (for ISP)

4. TXD (for ISP) 12. Serial Data for DDC

5. Ground 13. HORIZ. SYNC

6. Ground-R 14. VERT. SYNC

7. Ground-G 15. Serial Clock for DDC

8. Ground-B

1

6

11 15

5

10

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1.5 Factory preset display modes

2. Theory of operation

This section describes the operation theory of the N1750W LCD TV.

2.1 Video

“Analog Device” AD9883 shall provide analog to digital converter for this product. Video decoder shall be provided by
“Micronas” with a model number of VPC3230, and the de-interlace of this product shall be provided by “Sunplus” with a Model
Number of SPV302. The following tables define this product’s video specifications.

Input Parameter Specification

CVBS Characteristics:
Video Amplitude Signal
DC Level Sync Pulse:

0.7(min.) – 1.1(max.) V

Typical. 0.3 V
S-Video Characteristics:
Video Amplitude Signal

Y : 1.0Vp-p W / Neg. Sync (IN 75 Ω )

C : 0.285Vp-p (IN 75 Ω )
Y, Pb, Pr Characteristics:
Video Amplitude Signal

Y:1.0Vp-p (IN 75 Ω)

Pb:0.7 Vp-p(IN 75 Ω),Pr:0.7 Vp-p (IN 75 Ω)
Video Bandwidth NTSC: 6 MHz Maximum
RGB Characteristics:
Signal Type
Sync Type
Input Signal Rating

Sync Level:
Frequency Range
Pixel Color
DDC Compliance
EDID Data Table

Analog VGA

TTL, Separate Sync, with 4.7KΩ pull-down resistors

1250mV Max without damage to the product, 0-700 mV Full Range

2.5-5.25 V

Horizontal: 31.5-61K Hz, Vertical: 60-75 Hz

16 M

DDC2B Compliant

See Appendix B

Horizontal Vertical

Mode Resolution

Nominal Frequency

(KHz)

Nominal Frequency

(Hz)

640x480 31.5 60

640x480 37.9 72

640x480 37.5 75

VESA VGA

720x400 31.5 70
800x600 37.9 60
800x600 48.1 72

SVGA

800x600 46.9 75

VESA XGA 1024x768 48.4 60

MAC16” 832x624 49.725 74.55
MAC19” 1024x768 60.24 75

SVGA CVT 1280x768 47.8 60

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2.2 Audio

Audio processor of this product used a “SONY” CXA2104 audio decoder (for MTS) or “Micronas” MSP3425G (for NICAM),

and used a “YAMAHA” YDA135 audio processor amplifier. In addition, a pair of speakers shall be integrated within this
product. The audio signals of this product shall comply with the specification listed in the following table.

Parameter Specification

Tuner Input Base band Input

Speaker Power Output Max
Rating

2W at 3 % T.H.D Distortion 2W at 3% T.H.D Distortion

Speaker Impedance

8 Ω 8 Ω

Line In Per Tuner Spec

Max. 1Vrms

Line Out

N/A N/A

Flatness of Amplitude
Response

3 dB ( 6KHz deviation, 40Hz to 15KHz) 3 dB (200-16 kHz)

Total Harmonic Distortion
(Po=0.1 to 2 W, f=100Hz­15KHz)

<10% <10%

Signal to Noise:

30 dB (40Hz to 15KHz) 40dB (400Hz to 20 kHz)

2.3 Electrical

The following table defines the electrical specification of this product.

ELECTRICAL SPECIFICATION

1 Power Input Voltage Range 100-240VAC +/- 10% Wide Range

2 Input Frequency Range

47-60 Hz ±3Hz

3

Input Current 1.5A @ 230VAC

4 Power Supply Inrush

Max in < 35A (with fully loaded power supply) at 110Vac

Shall not result in permanent failure of power supply (including blown fuse)

5 Power Consumption:

Normal: 70 W (Max) // Sleep: < 3W (< 3W, when Power Off)

6 Interference with RF and Video

There shall be no visible interference between power supply, RF and video
signals. This applies to all available RF channels and video modes.

7 Electromagnetic Compatibility

This product shall adhere to the compatibility and immunity specifications in
FCC.

8

Power Supply Transient Immunity
(Supply Transients and Outage)

Able to withstand an ANSI / IEEE C62.41 – 1980 6000V 200A ring wave
with no damage.

9 Surge Immunity Test

Able to withstand 1.5X nominal Line Voltage for one cycle with no damage.

10

Power Supply Missing Cycle
Immunity

Function properly without reset or visible screen artifact when ½ cycle of AC
Power is randomly missing.

11 Power Supply Acoustics

The Power Supply shall not produce audible noise that would be detectable
by the user (Excluding Power Supply Fan).
“Audible” shall be defined in accordance with ISO 7779 (DIN
EN27779:1991).
Power Switch noise shall be Excluded.

12

Efficiency >= 70% @ full load, nominal line

13 Leakage Current <3.5mA @ 110VAC

14

Power Saving

When system is “OFF”, some minimal (<5W) power shall be consumed.

15 Recovery Time < 3 sec.

16

Power Factor Correction Compliant with EN61000-3-2

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3. Adjustment

3.1 Front panel adjustment

The following front panel adjustments are available for N1750W.
POWER switch: This switch shall be visible and accessible on the down right side of front PC frame. Soft Power Switch
(TURN ON SYSTEM) and one push of Soft-Power Switch shall turn on the system.
Note: This switch is not considered the “Mains Disconnection Device” for agency purposes. The AC switch in back cover
of product can also disconnect power. The power cord is the main disconnection device.

Power Indicator LED: This LED will illuminate “Green” light when the product is ON and “Red” light when the product in
stand-by mode.

CH +/-: These two switches shall be visible and accessible on the bottom of front panel control keys. While TV/CATV is
selected as input source, activation of these keys will cycle through all available TV/CATV channels. While OSD menu is
up, activation of these keys will highlight each available adjustment. The activation time for this switch includes Press and
Hold should be less than half second.

VOL +/-: These two switches shall be visible and accessible on the bottom of front panel control keys. Activation will
increase /decrease loudness of the audio output. In addition, while OSD menu is up, activation of these keys will regulate a
pre-selected adjustment. The activation time for this switch includes Press and Hold should be less than half second.

MENU: This switch shall be visible and accessible on the left side of VOL - switches. Once pressed, this key shall bring
up the corresponding OSD menu(s) based on the selected input source.

SOURCE: This switch shall be visible and accessible on the right side of VOL + switches. Once pressed, this key shall
toggle in a closed loop of the input source selection from TV, AV1, AV2, S-Video, Component, PC

Headphone: This connector is designed purpose to use headphone. Once the headphone connected, then the speakers will
auto mute on audio output.

3.2 How to use the menu

1. Press the MENU button to display each menu

2. Use the cursor up/down to select a menu item.

3. Use the cursor left/right to enter a submenu or enable/disable the function.

4. Press the MENU button to exit the menu.

OSD Table for N1750W

Items Description

TV / VIDEO MODE

Brightness Adjust the Black levels from 0 to 100
Contrast Adjust the White levels from 0 to 100
Saturation Adjust the color from light to heavy
Tint Adjust from Red to Green
Sharpness Adjust the Sharpness levels from 0 to 10
Black Level Adjust the Black light from 0 to 100
Volume Adjust the Volume levels from 0 to 100
Treble Adjust the Hi Frequency from light to heavy
Bass Adjust the Low Frequency from light to heavy
W / Head Phone No function at this model
SRS Enable SRS or disable SRS
Caption Selections Close Caption on or off .
Mode Selection Caption or Text for C.C
Channel Selections CC1 or CC2 or Text1 or Text2
Display Selection display Box or shadow for C.C
V-Chip V-Chip relative setting
Status Setting V-Chip function enable or disable
TV Guidelines TV Guidelines Setting
Movie Guidelines Movie Guidelines Setting
Change Pin Change Pin for V-Chip control
Sleep Timer Setting time to auto turn TV off
Set Up Setting TV basic function

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Blue Screen Sets Blue Screen on or off
Language Selections English, Spanish or French
Air / Cable Selections Air TV input or Cable TV input
Ch. Search Channel auto search by TV set
CH. Del ‹ Add › Skip or add current channel
View Mode Select view mode at 4:3 or 16:9 or non-Linear
Reset Reset TV to default value

PC

Brightness Adjust the Black levels from 0 to 100
Contrast Adjust the White levels from 0 to 100
Focus Adjust the color from light to heavy
H Position Adjust screen horizontal position
V Position Adjust screen vertical position
Auto Fine tuning clock and phase
Volume Adjust the Volume levels from 0 to 100
Treble Adjust the Hi Frequency from light to heavy
Bass Adjust the Low Frequency from light to heavy
SRS Enable SRS or disable SRS
Language Selections English, Spanish or French
PIP Select PIP relative function.
Position Adjust Sub-screen position
Source Selections Sub-screen display TV or AV1 or AV2 or S-Video
Audio Select Select audio from main-screen or sub-screen
Warm Setting color Temp. warm
Cool Setting color Temp. cool
Clock Adjust PC display clock for better performance
Caption Selections Close Caption on or off .
Mode Selection Caption or Text for C.C
Channel Selections CC1 or CC2 or Text1 or Text2
Display Selection display Box or shadow for C.C
Red Setting color Temp. more red.
Green Setting color Temp. more green.
Blue Setting color Temp. more blue.
Color Color Temp. Relative setting

V-Chip V-Chip relative setting f
Status Setting V-Chip function enable or disable
TV Guidelines TV Guidelines Setting
Movie Guidelines Movie Guidelines Setting
Change Pin Change Pin for V-Chip control

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4. Assembly and disassembly procedure

This section covers disassembly and reassembly of the N1750W LCD TV. Removal of external casing, its individual parts or

internal components can render the product dangerous. There can be a risk of electric shock from exposed components even when
the device is not connected to a power source.

4.1 Disassembly

1. Remove the cover rear as arrow direction

2. Unscrew and remove eleven screws marked red.

3. Remove the back rear.

For a screw under
the base

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4. Unscrew and remove four screws marked red.

5. Remove the shield as arrow direction.

6. Unscrew and remove six screws marked red in power board.

7. Remove the connector wire marked blue in power board.

8. Unscrew and remove four screws marked red in main board.

9. Remove the connector wire marked blue in main board.

10. Remove the power board and main board synchronously

Two speakers

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LCD Panel

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5. Exploded view