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VA1930wm-1,VS11354
Service manual
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ViewSonic VA1930wm-1,VS11354 Service manual

Service Manual
ViewSonic VA1930wm-1
Model No. VS11354
19” Color TFT LCD Display
(VA1930wm-1_SM Rev. 1a Nov. 2006)
ViewSonic 381 Brea Canyon Road, Walnut, California 91789 USA - (800) 888-8583
Copyright
Copyright © 2006 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
Optiquest is a registered trademark of ViewSonic Corporation. 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 SM Editing Date ECR Number Description of Changes Editor
1a 11/01/2006 Initial Release Jamie Chang
i
TABLE OF CONTENTS
1. Precautions and Safety Notices 1
2. Specification 4
3. Front Panel Function Control Description 11
4. Circuit Description 17
5. Adjustment Procedure 28
6. Troubleshooting Flow Chart 39
7. Recommended Spare Parts List 47
8. Exploded Diagram and Exploded Parts List 49
9. Block Diagram 52
10. Schematic Diagrams 53
11. PCB Layout Diagrams 60
ii
1. Precautions and Safety Notices
1. SAFETY PRECAUTIONS
This monitor is manufactured and tested on a ground principle that a user’s safety comes first. However,
improper used or installation may cause damage to the monitor as well as to the user.
WARNINGS:
z This monitor should be operated only at the correct power sources indicated on the label on the rear of the
monitor. If you’re unsure of the power supply in you residence, consult your local dealer or Power Company.
z Use only the special power adapter that comes with this monitor for power input.
z Do not try to repair the monitor by yourself, as it contains no user-serviceable parts. Only the qualified
technician can repair it.
z Do not remove the monitor cabinet. There are high-voltage parts inside that may cause electric shock to
human bodies.
z Stop using the monitor if the cabinet is damaged. Have it checked by a service technician. z Put your monitor only in a lean, cool, dry environment. If it gets wet, unplug the power cable immediately and
consult your closed dealer.
z Always unplug the monitor before cleaning it. Clean the cabinet with a clean, dry cloth. Apply non-ammonia
based cleaner onto the cloth, not directly onto the glass screen.
z Do not place heavy objects on the monitor or power cord.
2. PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in this chassis have special safety visual inspections and the protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Before replacing any of these components read the parts list in this manual carefully. The use of substitute replacement parts, which do not have the same safety characteristics as specified in the parts list, may create shock, fire, or other hazards.
3. SERVICE NOTES
z When replacing parts or circuit boards, clamp the lead wires around terminals before soldering.
z Keep wires away from high voltage, high temperature components and sharp edges.
z Keep wires in their original position so as to reduce interference.
z Adjustment of this product please refers to the user’ manual.
1
4. Handling and Placing Methods
2
3
2. Specification
1. INTPRODUCTION
TFTLCD PANEL
Input Signal
Sync Compatibility
Compatibility
FEATURES
Size
Luminance (Typ)
Contrast Ratio (Typ) 700:1
Colors (6 bits + 2 bits FRC) 16.2 M
Response Time (Typ) 5 ms
Viewing Angle (H/V) 160 ° / 160 °@>=10
Recommend resolution 1440x900@60Hz
Analog (75ohms, 0.7/1.0 Vp-p) Yes
Digital Yes
Separate Sync Yes
Composite Sync Yes
Sync on Green Yes
PC Yes
Power Mac Yes
TV Box (NextVision 6) Yes
VA1930wm
19 ”
300 cd/㎡
Power Voltage AC 100-240V, 50/60Hz Yes
Power Consumption
Audio Yes
Ergonomics
OSD Control [ 1 ] [ 2 ] [ ][▼] [▲] Yes
Dimension
Weight
Operating Condition
Storage Condition
On Mode(Max / Typ) 43 W/38W
Off Mode (Max)
Tilt ( 20 ° - -5 °)
Swivel Yes
Pivot No
Height Adjust Yes
Physical (W x H x D) 460 x 434 x 230 mm
Package (W x H x D) 560 x 525 x 282 mm
Physical (Net Weight) 5.4 kg
Package (Gross Weight) 6.9 kg
Temperature ( / )℉℃ 32℉-104 / ℉ 0℃-40℃
Humidity (%) 10 % - 90 %
Temperature ( / )℉℃ -4℉-140 / ℉ -20℃-60℃
Humidity (%) 10% - 90 %
≦1 W
Yes
UL, CUL, FCC-B (ICES), CB, CE, TCO'03, ICES-003B, ISO13406-2, TUV/GS, TUV ERGO(covers
Regulation
ISO13406-2 & MPRII), TUV-S, NOM, GOST-R, HYGIENIC (20 copies), ENERGY, Energy Star,
CCC, BSMI, PSB, C-TICK, KTL/MIC, SASO, WEEE, RoHS
4
2 GENERAL specification
Test Resolution & Frequency 1440x900 @ 60Hz
Test Image Size Full Size
Contrast and Brightness Controls
Factory Default:
Contrast = 70%, Brightness = 100%
3 VIDEO INTERFACE
Analog Input Connector DB-15 (Analog), refer the appendix A
Video Cable Strain Relief Equal to twice the weight of the monitor for five minutes
Video Cable Connector DB-15 Pin out Compliant DDC 1/2B
Video Signals Video RGB (Analog) – Separate,
Video Impedance 75 Ohms (Analog)
Maximum PC Video Signal 950 mV with no damage to monitor
Maximum Mac Video Signal 1250 mV with no damage to monitor
DDC 1/2B Compliant with Revision 1.3
Sync Compatibility Separate Sync
Video Compatibility
Shall be compatible with all PC type computers, Macintosh
computers, and after market video cards
640 x 350, 640 x 480, 720 x 400 (640 x 400*), 800 x 600,
Resolution Compatibility
Exclusions Not compatible with interlaced video
832 x 624, 1024 x 768, 1152 x 864, 1280 x 960, 1280 x
1024,1440x900
4 POWER SUPPLY
Internal Power Supply Part Number:RLPR-025
Input Voltage Range 90 to 264 VAC
Input Frequency Range 47 to 63 Hertz
Short Circuit Protection Output can be shorted without damage
Over Current Protection 4 A typical at 14.2 VDC
Leakage Current 3.5mA (Max) at 254VAC / 60Hz
Efficiency 80% typical at 115VAC Full Load
Fuse Internal and not user replaceable
Power Dissipation 38 Watts (typ)
Max Input AC Current 0.8 Arms @ 90VAC, 0.4 Arms @265VAC
Inrush Current (Cold Start) 40 A @ 120VAC, 60 A (max) @ 220VAC
Shall start and function properly when under full load, with
Power Supply Cold Start
Power Supply Transient Immunity Shall be able to withstand an ANSI/IEEE C62.41-1980
all combinations of input voltage, input frequency, and
operating temperature
5
2000V 200 ampere ring wave transient test with no
damage
Power Supply Line Surge Immunity
Power Supply Missing Cycle Immunity
Power Supply Acoustics
US Type Power Cable
European Type Power Cable
Shall be able to withstand 1.5 times nominal line voltage for
one cycle with no damage
Shall be able to function properly, without reset or visible
screen artifacts, when ½ cycle of AC power is randomly
missing at nominal input
The power supply shall not produce audible noise that
would be detectable by the user. Audible shall be defined
to be in compliance with ISO 7779 (DIN EN27779:1991)
Noise measurements of machines acoustics. Power Switch
noise shall not be considered
Separate 3-prong NEMA 5-15P type plug. Length = 1.8m.
Connects to display.
Color = Black
Schuko CEE7-7 type plug.
Length = 1.8m, Connects to display.
Color = Black
Separate 3-prong type plug.
CCC Type Power Cable
PSE Type Power Cable
Power Saving Operation(Method) VESA DPMS Signaling
Power Consumption
Recovery Time On Mode = N/A, Active Off < 3 sec
Length = 1.8m. Connects to display.
Color = Black
Separate 2-prong NEMA 1-15P type plug. Length = 1.8m.
Connects to display.
Color = Black
On Mode <42 W (max)
Off Mode< 1W
5 ELECTRICAL REQUIREMENT
Horizontal / Vertical Frequency
Horizontal Frequency
Vertical Refresh Rate
Maximum Pixel Clock 135 MHz
30 – 82 kHz
50 – 75* Hz.
Sync Polarity Independent of sync polarity.
6
Timing Table
SOG
Digital - TMDS
Remark
Analog
Composite
Separated
Item Timing
1 640 x 350 @ 70 Hz, 31.5 KHz 　 　 　 　 DMT 2 640 x 400 @ 60 Hz, 31.5 KHz 　 　 　 　 3 640 x 400 @ 70 Hz, 31.5 KHz 　 　 　 　 4 640 x 480 @ 50 Hz, 24.7 KHz 　 5 640 x 480 @ 60 Hz, 31.5 KHz 　 　 　 　 DMT 6 640 x 480 @ 67 Hz, 35 KHz 　 　 　 　 For MAC 7 640 x 480 @ 72 Hz, 37.9 KHz 　 　 　 　 DMT 8 640 x 480 @ 75 Hz, 37.5 KHz 　 　 　 　 DMT
9 720 x 400 @ 70 Hz, 31.5 KHz 　 　 　 　 10 720 x 480 @ 60 Hz, 31.5 KHz 　 　 　 　 DTV 11 720 x 576 @ 50 Hz, 31.3 KHz 　 DTV 12 800 x 600 @ 56 Hz, 35.1 KHz 　 　 　 　 DMT 13 800 x 600 @ 60 Hz, 37.9 KHz 　 　 　 　 DMT 14 800 x 600 @ 72 Hz, 48.1 KHz 　 　 　 　 DMT 15 800 x 600 @ 75 Hz, 46.9 KHz 　 　 　 　 DMT 16 832 x 624 @ 75 Hz, 49.7 KHz 　 　 　 　 MAC 17 1024 x 768 @ 50 Hz, 39.6 KHz 　 18 1024 x 768 @ 60 Hz, 48.4 KHz 　 　 　 　 DMT 19 1024 x 768 @ 70 Hz, 56.5 KHz 　 　 　 　 DMT 20 1024 x 768 @ 72 Hz, 58.1 KHz 　 　 　 　 21 1024 x 768 @ 75 Hz, 60 KHz 　 　 　 　 DMT 22 1024 x 768 @ 75 Hz, 60.2 KHz 　 　 　 　 For MAC 23 1152 x 864 @ 75 Hz, 67.5 KHz 　 　 　 　 DMT 24 1152 x 870 @ 75 Hz, 68.7 KHz 　 　 　 　 For MAC 25 1152 x 900 @ 67 Hz, 62.5 KHz 　 　 　 　 For SUN 26 1280 x 720 @ 50 Hz, 37.5 KHz 　 　 　 　 DTV 27 1280 x 720 @ 60 Hz, 45 KHz 　 　 　 　 DTV 28 1280 x 768 @ 50 Hz, 39.6 KHz 　 29 1280 x 768 @ 60 Hz, 47.8 KHz 　 　 　 　 DMT; 30 1280 x 768 @ 75 Hz, 60.3 KHz 　 　 　 　 DMT; 31 1280 x 960 @ 50 Hz, 49.4 KHz 　 32 1280 x 960 @ 60 Hz, 59.7 KHz 　 　 　 　 DMT 33 1280 x 960 @ 75 Hz, 75.2 KHz 　 　 　 　 34 1280 x 1024 @ 50 Hz, 52.7 KHz 　 35 1280 x 1024 @ 60 Hz, 64 KHz 　 　 　 　 DMT 36 1280 x 1024 @ 75 Hz, 80 KHz 　 　 　 　 DMT 37 1440 x 900 @ 60 Hz 59.9 KHz 　 　 　 　 DMT
Primary Presets
1440x900 @ 60Hz
User Presets
Number of User Presets (recognized timings) Available: 10 presets total in FIFO configuration
Changing Modes
z Maximum Mode Change Blank Time for image stability: 3 seconds (Max), excluding “Auto Image Adjust” time.
z Under DOS mode (640 x 350, 720 x 400 & 640 x 400), it should recall factory setting when execute “Auto
Image Adjust”.
The monitor needs to do “Auto Image Adjust” the first time when a new mode is detected. (See section “0-Touch™ Function Actions”)
7
6 FRONT PANEL CONTROLS AND INDICATORS
Front Panel Hardware Controls
Power Switch (Front Head) Power Control, soft Power Switch.
Green – ON
Power LED (Front Head)
Front Panel Controls (Head)
[
] [ 1 ] [ 2 ] [▲] [▼]
Reaction Time
Short Cuts Function from the button(s)
Orange – Active Off
Dark = Soft Power Switch OFF
[;X] Mute
[
] Power
[ 1 ] Button 1
[ 2 ] Button 2
[▲] Up arrow button
[▼] Down arrow button
Note: Power Button, Button 1 and Button 2 must be
one-shot logic operation. (i.e. there should be no
cycling)
OSD must fully appear within 0.5s after pushing Button
1
[1] Main Menu
[2] Input toggle (Analog or Digital; refer to Appendix D)
[▼] Brightness adjust
[▲] Contrast adjust
[▼]+ [▲] recall both of Contrast and Brightness to default
[1] + [2] toggle 720x400 and 640x400 mode when input 720x400 or 640x400
mode
[1] + [▼] + [▲] White Balance. (Not shown on user’s guide)
[1] + [▼] Power Lock
[1] + [▲] OSD Lock
[1] + [▼] + [2] Disable Theft Defence function
[▲]+ [ ] + Main Power On All reset
No signal + [ ] + [2]
+ Main Power on
Signal + [2] + [ ] + Main Power
On
Burning mode
Factory Mode
Remark : All the short cuts function are only available while OSD off
8
Main Menu Controls
The Main Menu OSD includes most of control functions.
Please refer to APPENDIX C (Main Menu OSD Table) for the detail.
Function descriptions
OSD Lock short cuts function for the buttons
The OSD lock will be activated by pressing the front panel control buttons "(1), & (▲)" for 10 seconds. If the
user then tries to access the OSD by pressing any of the buttons "1", "▼", "▲", "2" a message will appear on
the screen for 3 seconds showing "OSD Locked". The OSD lock will be deactivated by pressing the front
panel control buttons "(1), & (▲)" again for 10 seconds.
Note1: When the OSD is locked will lock all functions, including “Volume” and “Mute”
Note 2: Status bar indicating OSD Lock or Unlock is in progress and when complete it will indicate “OSD
Locked”
Note 3: OSD Lock should not lock Power Button and Power Lock function
Power Lock short cuts function for the buttons
The power button lock will be activated by pressing the front panel control buttons "(1), & (▼)" for 10 seconds.
Locking the power button means that the user won't be able to turn off the LCD while the power button is
locked. If the user presses the power button while it is locked, a message will appear on the screen for 3
seconds showing "Power Button Locked". It also means that with the power button locked, the LCD would
automatically turn back "On" when power is restored after a power failure. If the power button is not in the
locked mode, then power should return to it's previous state when power is restored after a power failure. The
power button lock will be deactivated by pressing the front panel control buttons "(1), & (▼)" again for 10
seconds.
Note 1: Status bar indicating Power Button lock or unlock is in progress and when complete it will indicate
“Power Button Locked”
Note 2: Power should only be lockable in the “On State”
Memory Recall Actions
Memory Recall action on the analog and digital mode as below
1. Recall white balance to factory setting
2. Set the factory defaults as shown in Section 4-8
3. Clean all the mode setting buffer
4. Execute Auto Image Adjust
Note: Memory Recall should have no effect for Language, Power Lock, User Color Settings or Input Priority
Resolution Notice Actions
1. Resolution Notice OSD should show on screen after changing to non-native mode for 30 sec
2. For auto input select function, it shall meet the requirement in Appendix D.
3. The OSD should disappear after 10 sec or by pushing button [1] or [2]
Resolution Notice function should be disabled when push button [2] under Resolution Notice OSD
9
0-Touch™ Function Actions
1. Execute Auto Image Adjust when new mode detected, and save the settings to buffer for further use
2. It should be reset by Memory Recall function(Should not reset by power off, power unplug and others)
OSD Auto Save
The OSD shall save new settings when it is turned off by the user or when it times out. There shall not be a
separate save
10
3. Front Panel Function Control Description
Main Menu
with OSD controls
Front Control Panel
shown below in detail
Standby Power On/Off Power light Blue = ON Orange = Power Saving
Audio Mute button turns the sound off
Displays the Main Menu or exits the control screen and saves adjustments.
Scrolls through menu options and adjusts the displayed control. Also a shortcut to display the Contrast adjustment control screen.
Displays the control screen for the highlighted control. Also toggles between two controls on some screens.
11
Do the following to adjust the display setting:
1. To display the Main Menu, press button [1].
NOTE: All OSD menus and adjustment screens disappear automatically after about 15
seconds. This is adjustable through the OSD timeout setting in the setup menu.
2. To select a control to adjust, pressSorTto scroll up or down in the Main Menu.
3. After the desired control is selected, press button [2]. A control screen like the one shown
below appears.
The command line at the bottom of the control screen tells what to do next from this screen. You can toggle between control screens, adjust the selected option, or exit the screen.
4. To adjust the setting, press the up S or down T buttons.
5. To save the adjustments and exit the menu, press button [1] twice.
The following tips may help you optimize your display:
• Adjust the computer's graphics card so that it outputs a 1440 x 900 @ 60Hz video signal to the LCD display. (Look for instructions on “changing the refresh rate” in the graphics card's user guide.)
• If necessary, make small adjustments using H. POSITION and V. POSITION until the screen image is completely visible. (The black border around the edge of the screen should barely touch the illuminated “active area” of the LCD display.)
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Main Menu Controls
Adjust the menu items shown below by using the up S and down T buttons.
Control Explanation
Auto Image Adjust sizes and centers the screen image automatically.
Contrast adjusts the difference between the image background (black level)
and the foreground (white level).
Brightness adjusts background black level of the screen image.
Input Select toggles between inputs if you have more than one computer
connected to the VA1930wm.
Audio Adjust Volume increases the volume, decreases the volume, and mutes the audio. Mute temporarily silences audio output.
Color Adjust provides several color adjustment modes, including preset color
temperatures and a User Color mode which allows independent adjustment of red (R), green (G), and blue (B). The factory setting for this product is 6500K (6500 Kelvin).
sRGB-This is quickly becoming the industry standard for color management, with support being included in many of the latest applications. Enabling this setting allows the LCD display to more accurately display colors the way they were originally intended. Enabling the sRGB setting will cause the Contrast and Brightness adjustments to be disabled.
9300K-Adds blue to the screen image for cooler white (used in most office settings with fluorescent lighting).
7500K-Adds blue to the screen image for cooler white (used in most office settings with fluorescent lighting).
6500K-Adds red to the screen image for warmer white and richer red.
5400K-Adds green to the screen image for a darker color.
13
Control Explanation
User Color Individual adjustments for red (R), green (G), and blue (B).
1. To select color (R, G or B) press button [2].
2. To adjust selected color, pressSandT.
Important: If you select RECALL from the Main Menu when the product is
set to a Preset Timing Mode, colors return to the 6500K factory preset.
Information displays the timing mode (video signal input) coming from the graphics card in the computer, the LCD model number, the serial number, and the ViewSonic® website URL. See your graphics card’s user guide for instructions on changing the resolution and refresh rate (vertical frequency). NOTE: VESA 1440 x 900 @ 60Hz (recommended) means that the resolution is 1440 x 900 and the refresh rate is 60 Hertz.
Manual Image Adjust
H. Size (Horizontal Size) adjusts the width of the screen image.
H./V. Position (Horizontal/Vertical Position) moves the screen image left or
right and up or down.
14
Control Explanation
Fine Tune sharpens the focus by aligning text and/or graphics with pixel boundaries.
NOTE: Try Auto Image Adjust first.
Sharpness adjusts the clarity and focus of the screen image.
Setup Menu displays the menu shown below:
Language Select allows the user to choose the language used in the menus and
control screens.
Resolution Notice allows the user to enable or disable this notice.
If you enable the Resolution Notice shown above and your computer is set at a
resolution other than 1440 x 900, the following screen appears.
OSD Position allows the user to move the OSD menus and control screens.
OSD Timeout sets the length of time the OSD screen is displayed. For example,
with a “30 second” setting, if a control is not pushed within 30 seconds, the display screen disappears.
15
Control Explanation
OSD Background allows the user to turn the OSD background On or Off.
Memory Recall returns the adjustments back to factory settings if the display is
operating in a factory Preset Timing Mode listed in the Specifications of this manual.
16
4. Circuit Description
2. Electronic Circuit Theory
2.1 Switching Mode Power Supply
2.1.1 AC Current Input Circuit P801 is a connector for connecting AC Power. F801 is a fuse to protect all the circuit. AC
input voltage is from 90v to 264V. R801 and R802 joined between two inputting main circuit to prevent man from shock. L801 is used to clear up low frequency wave. C801 and C802 are used to discharge the waves that L801 produced. High frequency waves are damped by C801 and C802. D801 is a rectifier which composed of 4 build-in diodes, it inverts AC to DC.
2.1.2 High Voltage to Low Voltage Control Circuit C804 is used to smooth the wave from rectifier. IC802 is a highly integrated PWM controller.
When rectified DC high voltage is applied to the HV pin during start-up, the MOSFET Q804 is initially off, and the Vcc pin capacitor is charged. When the Vcc pin voltage reaches approximately 10V, the control circuitry is activated and the soft-start begins. The soft-start circuit gradually increases the duty cycle of the MOSFET from zero to the maximum value over approximately 4ms. If no external feedback/supply current is fed into the FB pin by the end of the soft-start, the current Setpoint will be above the fault level, FAULT flag is raised, if the FAULT duration exceeds 80ms, the output controller disable
Resistor R808, R809, R810, R811 are for line over voltage shutdown(OVP) When PWM is turned off, the main current flow will be consumed through R804 and D802,
This will prevent MOSFET Q804 from being damaged under large current impulse and voltage spike.
D803 and C807 to provide internal Auxiliary voltage to Vcc pin during normal operation.
Otherwise, error amplifier and feedback current input the FB pin for duty cycle control.
2.1.3 DC_5V and DC_14V Output Circuit For DC 5V, D805 is used to rectify the inducted current. R828 and C814 are used to store
energy when current is reversed. The parts including C818, C822, C820,L803 are used to smooth the current waves.
For DC 14V, D803 is used to rectify the inducted current. R827 and C813 are used to store
energy when current is reversed. The parts including C815, C817 and L802 are used to smooth the current waves.
2.1.4 Feedback and OVP Protect Circuit Pin R of IC803 is supplied 2.5-v stable voltage. It connects to 5V and 14V output through
R822, R823 and R824. R822, R823 and R824 are output sampling resistor. When the sampling voltage more than 2.5V or less than 2.5V, current of FB IC802 will change, this can change the voltage from T801.
OVP Protect Circuit: When output is overvoltage, the auxiliary winding voltage will be
increased, when it reaches about 14V. Q803 is triggered . It makes the IC802 Pin 1 exceed 5V, then the IC802 output will be disabled.
17
Q801, R816, R817 and ZD803 make up of dummy loading circuit. For start-up sequence,
during 5V output take place high loading first, this dummy loading circuit operated to insure 14V not be increased.
2. 2 Inverter Circuit
1R503, ZD501, R502, Q501 components convert +14V voltage into +5.0V voltage, and the voltage supply to IC501. The extra PWM pulse signal (BRIGHTNESS signal)input to con trol IC through R512, R514, C510, The LCT pin is set to a DC voltage of 0.7V by using a resistor divider(R507, R516), change the duty of PWM pulse, will regulate the lamp current. The ON/OFF voltage connect to pin10 of IC501 through D501, R501, A voltage of 2V to pin10 of IC501 enables the IC and activates the striking timer. The SSTCMP pin of IC501 performs the soft function, the C511 set the time of SST. The operation frequency determined by external capacitor C512, C521 and resistor R508 connected at CT pin of IC501. C515 connect the TIMER pin of IC501, the capacitor to set striking time and shunt down delay time. DRV!, DRV2 output for power MOSFET U501, U502.
2.OZ9938 provides two drive signals forU501, U502, and they work in push pull topology driving, two transformers are connected in parallel with each transformer driving two lamps in series.Turningeach N-Channel MOSFET “on/off＂ complementarily, produces an alternating current through thetransformer primary and secondary. The “on＂ dur ation of the
switches determines the amount of energy delivered to the CCFLs. R504, C504, R505, C505, R532, C529, R530, C522 are snubber networks, they suppress Voltage transient spike in drain of power MOSFET.
3. R506, R510, C509, C513, C514, R525, R531, C528, C525, and C527 are connected betweenh igh voltage output connector and ground, the divided AC voltage is inverted DC voltage through D502, D503, D508, and D509.The sense voltage feedback to VSEN (pin 6 of IC501) for an over voltage/over current condition during normal operation. R528, R533 are current sense resistor, current sense signal feed back to Isense (pin 5 of IC501) for lamp “ON＂ detection.
2.2 I/F Board Circuit
2.2.1 Power Input
+5V is from the power board and supply for U101(LD1117AL-3.3V)､U105(TSUM56AL-1) and panel. +3.3V
output is generated from +5V through C101 and C103 filtering, and U101 outputs. +3.3V is used for U105
(MCU & Scaler: TSUM16AL). +1.8V output is generated from +3.3V through U102 outputs. +1.8V is only used
for U105.
2.2.2 MCU & Scaler(TSUM56AL-LF-1)
The frequency of XTAL1 is 14.318MHz. U105 # 48 is defined as panel-enable. When the I/O port is high,
Q101 and Q103 are conducted. And then after C108 and C109 filtering, obtain the voltage of VLCD, which will
be connected to CN104. U105 # 85 is defined as CCFL-enable. When the I/O port is low, Q106 is pulled up
and the backlights are on; When the I/O port is high, Q106 is conducted and the backlights are off. U105 # 35
is defined as DET-VGA, connected with CN103 #5. U105 # 84 is a pin of hardware reset. U105 # 54-# 55,#
58-# 65, # 67-# 74, # 77-# 78 output LVDS digital data of 8 bit to panel control circuit through CN104. U105 #
86 generates a PWM waveform by regulating the duty to control the brightness of the backlights.
U103 is EEPROM used for saving EDID data, which is connected by SCL and SDA pins with # 31 and # 30 of
TSUM56AL-LF-1.
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