Dell ST2010 - 20" LCD Monitor User manual

Service Manual
-
0
-
Service Manual
LCD Monitor ST2010

1
Service Manual Versions and Revision
No. Version Release Date Revision
1 1.0 2009/02/11 Initial Release
Copyright
Copyright 2007 InnoLux Display. Corp. Ltd
All Rights Reserved
This manual may not, in whole or in part, be copied, Photocopied, reproduced, translated, or converted to any
electronic or machine readable form without prior written permission of Foxconn Tech. Corp. Ltd.
Dell ST2010 Service Manual

Service Manual
2
Table of Contents
CHAPTER 1- PRECAUTIONS & SAFETY NOTICES................................................................................................
......................
SAFETY PRECAUTIONS................................................................................................................................
................................
PRODUCT SAFETY NOTICE................................................................................................................................
.............................
SERVICE NOTES ................................................................................................................................
................................
CHAPTER 2- SERVICE TOOLS & EQUIPMENT REQUIRED................................................................
................................
CHAPTER 3- CIRCUIT THEORY................................................................................................................................
.......................
1.BLOCK DIAGRAM ................................................................................................................................
................................
2.ELECTRONIC CIRCUIT THEORY................................................................................................................................
...........................
3. FACTORYPRESETTIMING TABLE ................................................................................................
................................
4. POWER ON/OFF SEQUENCY ................................................................................................................................
.............................
5. D-SUB CONNECTOR PIN ASSIGNMENT................................................................................................
................................
6.AC OUTLET PIN ASSIGNMENT ................................................................................................................................
.........................
7. INNER CONNECTOR PIN ASSIGNMENT................................................................................................
................................
8. KEY PARTS PIN ASSIGNMENTS................................................................................................................................
.........................
CHAPTER 4- DISASSEMBLY & ASSEMBLY................................................................................................
................................
1. EXPLODED DIAGRAM................................................................................................................................
................................
2. ST2010 DISASSEMBLY BLOCK ................................................................................................................................
......................
3. ST2010ASSEMBLY BLOCK................................................................................................................................
............................
CHAPTER 5- TESTAND ADJUSTMENT................................................................................................
................................
5.1 FUNCTION KEY DEFINITIONS................................................................................................................................
..........................
5.2 OSD CONTROL................................................................................................................................
................................
5.3 OSD MESSAGE ................................................................................................................................
................................
5.4 BURN-IN PATTERN................................................................................................................................
................................
5.5AUTO COLOR BALANCE (AUTOMATICALLY CALIBRATE CHIPADC PARAMETER BY USING CHIP
INTERNAL DAC.)................................................................................................................................................................
.................
5.6 UPGRADE FIRMWARE TO SERIAL VIA FLASH CABLE BY ISP_TOOLV4.100.EXE ................................
................................
CHAPTER 6- TROUBLE SHOOTING................................................................................................
................................
1. COMMON ACKNOWLEDGE ................................................................................................................................
...............................
2. NO POWER SUPPLY ................................................................................................................................
................................
3. POWER (INCLUDE IF +5VAND +3.3V) SUPPLY NORMAL BUT LED OFF AND NO DISPLAY ................................
................................
4. POWER (INCLUDE IF +5VAND +3.3V) SUPPLYAND DISPLAY NORMAL ONLY LED OFF................................
................................
5. POWER (INCLUDE IF +5VAND +3.3V) SUPPLY NORMAL BUT LEDAMBER ................................................................
.......................
6. POWER (INCLUDE IF +5VAND +3.3V) SUPPLY NORMAL ,KEY FUNCTION OK,BUT BACKLIGHT CAN’T
BE TURNED ON................................................................................................................................................................
.....................
7. BACKLIGHT ON,KEY FUNCTION AND LEDACCURATE INDICATION OK BUT NO PICTURE................................
................................
8. AT 32-GRAY SCALE PATTERN,COLOR LOST IN SOME SCALE................................................................
................................
CHAPTER 7- RECOMMENDED PART LIST................................................................................................
................................
ATTACHMENT 1- BILL OF MATERIAL ................................................................................................
................................
ATTACHMENT 2- SCHEMATIC................................................................................................................................
.......................
ATTACHMENT 3- PCB LAYOUT................................................................................................................................
......................

Service Manual
3
Chapter 1- PRECAUTIONS & SAFETY NOTICES
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:
lThis monitor should be operated only at the correct power sources
indicated on the rating label on the rear cover of the monitor. If you’re
unsure the power supply in your residence, consult your local dealer or
Power Company.
lUse only the specified power cord that comes with this monitor.
lDo not try to repair the monitor by yourself, as it contains no
user-serviceable parts. This monitor should only be repaired by a
qualified technician.
lDo not remove the monitor cabinet. There is high-voltage parts inside
that may cause electric shock to human bodies.
lStop using the monitor if the cabinet is damaged. Have it checked by a
service technician.
lPut your monitor only in a lean, cool, dry environment. If it gets wet,
unplug the power cable immediately and consult your closed dealer.
lAlways 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 class screen.
lDo not place heavy objects on the monitor or power cord.
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.
SERVICE NOTES
lWhen replacing parts on circuit boards, clamp the solder wires around
terminals before soldering.
lKeep wires away from high voltage, high temperature components and
sharp edges.
lKeep wires in their original position so as to reduce interference.
lAdjustment of this product please refers to the user’ manual.
lUse Pb free solder wire for circuit board preparation.

Service Manual
4
Chapter 2- SERVICE TOOLS & EQUIPMENT REQUIRED
1. SIGNAL GENERATOR
2. MULTIMETER
3. SCREW DRIVER
4. OSCILLOSCOPE
5. Soldering IRON
6. SOLDER (Lead free, RoHS compliance)
7. Color Analyzer
8. Fox_VISP_Programmer
9. Fox_VEDID_Programmer

Service Manual
5
Chapter 3- CIRCUIT THEORY
1.Block Diagram
Dell ST2010 consists of a main body and a stand (base). The main body contains a
LCD module with 2 CCFL lamps, There are 4pcs PCBA in this monitor, one is
power& inverter which is a single layer board, one is interface board, one is
function keypad which is OSD control located on the right side back cover,one is
power DC_on/off key. The block diagram is shown as below(fig.1).
Lamp2
Photocoupler
Transformer
Snubber
&Schottky
Feedback
Control
Snubber
&Schottky
1
To Panel CCFL
MOSFET
Rectifier&
Filter
Circuit
Brightness/ ON/OF
Control
Power
MOSFET
AC Input
90V~264V
PWM Control
IC LD7575
Feedback
and OVP
+13V DC output
Power
Transformer
Lamp1
AC Line Filter
INL816
Fuse 5A/125V
+5V DC output +5V DC output

Service Manual
6
Scalar
LVDS Data
Flash
Connector to power board
HDMI signal
3.3V
power saving control
Panel Vcc control
Panel Interface
TSUMU58EDJ-LF
5V 5V
1.8V
dynamic contrast ratio
3.3V
14.318MHz
Brightness /ON_OFF Control
AP1117E33A
VGAConnector
VGA signal
LM1117M-1.8
XTAL
OSD/KEY
24C16
EDID
24C02
HDMI Connector
Panel Vcc
on/off switch
Connector
LM1117M-3.3
Keypad
AP1117E18
EDID
24C02
Fig.1

Service Manual
7
2.Electronic Circuit Theory
2.1 Inverter PWM circuit
2.1.1 Inverter Control circuit operations:(fig.2)
GND
DRV2
R11
100K D1 BAV70
R8
33K
ISEN
PWM
+5V
CN5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
PIN1
PIN2
PIN3
PIN4
PIN5
PIN6
PIN7
PIN8
PIN9
PIN10
PIN11
PIN12
PIN13
PIN14
PIN15
C7
2.7n
U1
INL816
1
2
3
4
5
6
12
13
14
15
16
7
8 9
10
11
DRV1
VDDA
SEL
RT1
RT
PWM
OLP1
OLP2
SSTCMP
GND
DRV2
PID
TIMER ISEN1
ISEN2
VSEN
C2
10n
R10
20R
DRV1
+13V
R12
100K
DRV1
R3
10K
R7
33KC3
2.2u
VS1
C6
OPEN
C8
2.7n
R6
NC
R1 10R
R13
10K
R9
20R
Q1
AP9971
1
2
3
45 6
7
8
.
.
.
.. .
.
.
DIM/ON/OFF
C9
3.3n
VS1
R4 560K
Confidential
O2Micro Inc. All rights reserved
PID
C5
47n
C10
3.3n
R5
191K
+5V
OP
+13V
R2 10K
C1
1u
VS2
Fig.2
DC_5V through R1 and C1 will provide power for U1 on the
pin2.PWM-ON/OFFandDIM voltage signal coming from scalar which is on IF BD
will PWM U1 to work. During start up, ISEN (pin9and pin10) senses the voltage on
the transformer secondary. If no current is sensed approximately 2 seconds, U1 shuts
off. R3 is used to limit current. C3 is used to dump noise, C5 is used to soft start, and
then the voltage on pin 14 will enable U1.Once the voltage at the ISEN pin reaches
the lamp on threshold, the IC switches from the striking mode to the normal operation
mode and the PWM dimming control is activated.
The striking and operating frequency is determined by the external resistor
(R4andR5) and connected to Pin 4and Pin5.
DRV1 and DRV2 of U1 are used to drive U2 . DRV1 and DRV2 are controlled
by build-in PWM IC. Q1 is switched which has two build-in IGBTs. The working
principle of circuit of T1, the same to circuit of Power.
The voltage signal on negative pole of D1 sensed through R7/R8 comes to
Pin11 of U1 VSEN (Lamp Current Detection & Control). The CCFL current is
detected through R12/R21 and reaches a regulated value. The CCFL current detected
at resistor R12/R21 is converted to a voltage level and input to the ISEN. Once the
CCFLs are ignited and current is sensed through resistor R12/R21, performs the loop
compensation function. The voltage at IC pin12 controls the drive duty cycle of the

Service Manual
8
power MOSFETs to regulate the CCFL current.
2.1.2 Output Circuit and Protection Circuit operations:(fig.3)
1
2
+
C25
680u/25V
OP
C22
12pF/3KV
ISEN
DRV2
DRV2
VS2
ISEN
PID
CN5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
PIN1
PIN2
PIN3
PIN4
PIN5
PIN6
PIN7
PIN8
PIN9
PIN10
PIN11
PIN12
PIN13
PIN14
PIN15
VS2
DRV1
VS1
1
2
R21
133
+13V
C21
3pF/3KV
DRV1
OP
DIM/ON/OFF
T1
DIPEEL19 SPW-054
1
6
4
3
8
7
VS1
+5V
C20
3pF/3KV R20
133
+13V
Fig.3
The transformer (T1) secondary winding leakage inductance and output
capacitance(C31) forms a lower pass filter,which converts the square-wave driving
signal into a sinusoidal output voltage signal for CCFL.
The over-voltage protection feature is implemented by using an extermal
capacitor devider(C20/C21) to sense the output voltage.The divide-down voltage
signal is sent to the IC Pin11(VSEN) ,thus regulating the output voltage.
If a CCFL is removed, fails or damaged during normal operation, CCFL current
is no longer sensed and the voltage on ISEN pin drops. Once the voltage at the ISEN
pin is less than the lamp” on” threshold, the shutdown timer is activated. The IC
maintains the output voltage for approximately 2-3seconds and once the timer expires,
the IC will shutdown. To restart the IC, either toggle the SST_CMP pin or recycle the
power on the VDDA pin.
2.2 Power PWM circuit operations
2.2.1) Block diagram:(fig.4)
EMI Filter Rectifier and
filter Isolation power transformer Rectifier and filter Inverter circuit
Rectifier and filter AUDIO

Service Manual
9
R851 750K
C851
222 Y2
C850
222 Y2
L850
NC/CHK-106
4 3
1 2
C852
0.47uF X2
CN850
TU-301-AS
1 3
2
F850 3.15A 250V
R850 750K
VZ850 TVS
L850-1
CHK-090
4 3 1 2
AC INPUT(90V~265V) RT850
8R5A
Fig.4
2.2.2) AC Input and EMI Filter:(fig.5)
Fig.5
CN850 is a connector for connecting AC Power. F850 is a fuse to protect all the
circuit AC. Input voltage is from 90V to 264V. R850 and R851 are joined between
two inputting main circuit to prevent man from shock. L850 is used to filter low
frequency noise. C850 and C851 are used to discharge the noise that L851 produced.
High frequency waves are damped by C852 .
2.2.3)High Voltage to Low Voltage Control Circuit:(fig.6)