Hitachi CML155XW User manual

CAUTION:
Beforeservicingthischassis,itisimportantthattheservicetechnicianreadthe“Safety
Precautions”and“ProductSafetyNotices”inthisservicemanual.
ATTENTION:
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etles«Noticesdesécuritéduproduit»présentésdansleprésentmanuel.
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SERVICEMANUAL
MANUELD'ENTRETIEN
WARTUNGSHANDBUCH
DatacontainedwithinthisService
manualissubjecttoalterationfor
improvement.
Lesdonnéesfourniesdansleprésent
manueld’entretienpeuventfairel’objet
demodificationsenvuedeperfectionner
leproduit.
DieindiesemWartungshandbuch
enthaltenenSpezifikationenkönnensich
zwecksVerbesserungenändern.
NOV 2001
No. 0411
SPECIFICATIONSANDPARTSARESUBJECTTOCHANGEFORIMPROVEMENT
CML155XW

ENGLISH
SAFETY PRECAUTIONS
WARNING: The following precautions must be observed.
ALL PRODUCTS
Before any service is performed on the chassis an
isolation transformer should be inserted between the
power line and the product.
1. When replacing the chassis in the cabinet, ensure
all the protective devices are put back in place.
2. When service is required, observe the original
lead dressing. Extra precaution should be taken to
ensure correct lead dressing in any high voltage
circuitry area.
3. Many electrical and mechanical parts in
HITACHI products have special safety related
characteristics. These characteristics are often not
evident from visual inspection, nor can the
protection afforded by them necessarily be
obtained by using replacement components rated
for higher voltage, wattage, etc. Replacement
parts which have these special safety
characteristics are identified by marking with a
!on the schematics and the replacement parts
list.
The use of a substitute replacement component
that does not have the same safety characteristics
as the HITACHI recommended replacement one,
shown in the parts list, may create electrical
shock, fire, X-radiation, or other hazards.
4. Always replace original spacers and maintain lead
lengths. Furthermore, where a short circuit has
occurred, replace those components that indicate
evidence of overheating.
5. Insulation resistance should not be less than 2M
ohms at 500V DC between the main poles and
any accessible metal parts.
6. No flashover or breakdown should occur during
the dielectric strength test, applying 3kV AC or
4.25kV DC for two seconds between the main
poles and accessible metal parts.
7. Before returning a serviced product to the
customer, the service technician must thoroughly
test the unit to be certain that it is completely safe
to operate without danger of electrical shock. The
service technician must make sure that no
protective device built into the instrument by the
manufacturer has become defective, or
inadvertently damaged during servicing.
CE MARK
1. HITACHI products may contain the CE mark on
the rating plate indicating that the product
contains parts that have been specifically
approved to provide electromagnetic
compatibility to designated levels.
2. When replacing any part in this product, please
use only the correct part itemised in the parts list
to ensure this standard is maintained, and take
care to replace lead dressing to its original state,
as this can have a bearing on the electromagnetic
radiation/immunity.
PICTURE TUBE
1. The line output stage can develop voltages in
excess of 25kV; if the E.H.T. cap is required to be
removed, discharge the anode to chassis via a
high value resistor, prior to its removal from the
picture tube.
2. High voltage should always be kept at the rated
value of the chassis and no higher. Operating at
higher voltages may cause a failure of the picture
tube or high voltage supply, and also, under
certain circumstances could produce X-radiation
levels moderately in excess of design levels. The
high voltage must not, under any circumstances,
exceed 29kV on the chassis (except for projection
Televisions).
3. The primary source of X-radiation in the product
is the picture tube. The picture tube utilised for
the above mentioned function in this chassis is
specially constructed to limit X-radiation. For
continued X-radiation protection, replace tube
with the same type as the original HITACHI
approved type
4. Keep the picture tube away from the body while
handling. Do not install, remove, or handle the
picture tube in any manner unless shatterproof
goggles are worn. People not so equipped should
be kept away while picture tubes are handled
LASERS
If the product contains a laser avoid direct exposure to
the beam when the cover is open or when interlocks are
defeated or have failed.

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 2
TABLE OF CONTENTS
1. Precaution and Notices ………….……………………………………… 4
1.1 Safety Precaution ………….………………………………………. 4
1.2 Product Safety Notice ……………………………………………… 4
1.3 Service Notes ………………………………………………………. 4
2. Specifications ………….……………………………...………………… 5
2.1 Monitor Specifications ……..………………………………………. 5
2.2 Stereo Speaker …..…………………………………………………. 6
2.3 Timing Supported – Analog Inputs ..………………………………. 7
2.4 Timing Supported – Digital Inputs ..…………….…………………. 7
3. Control Buttons and Functions …………………………………………. 8
3.1 User Control Buttons ..……..………………………………………. 8
3.2 Power LED ..……..…………………………………………………. 9
3.2 Tilting the Displays …………………………………………………. 9
4. Disassembly Instructions ……………………………………………….. 10
5. General Connection and Applications ………………………………….. 12
5.1 Connecting the Monitor to the Computer ………………………….. 12
5.2 Connecting the Monitor to the AV device ………………………….. 14
6. Electronic Circuit Description ………………………………………….. 16
6.1 Main Board Circuit ……………………..………………………….. 16
6.2 Audio Board Circuit ………………………………………………… 18
6.3 Keyboard Circuit …………………………………………………… 18
6.4 Inverter Circuit …………………………..………………………….. 18
7 Troubleshooting Flow Chart ……………………………………………..19
8. Repair Parts List …………………………………................……………. 19
9. Mechanical Disassembly ………………..………………………………. 19
10. PCB Layout ……………………………..………………………………. 19

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 3
AppendixA.Main Board Block Diagram
Appendix B. Mainboard CircuitDiagrams
AppendixC. Audio Board Circuit Diagram
Appendix D. Keyboard CircuitDiagram
Appendix F.Troubleshooting Flow Chart
Appendix G.Proposed Repair Parts List
Appendix H. Mechanical Disassembly
AppendixI. PCB Layout
Appendix E. Inverter Circuit Diagram

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 4
1. Precautions and Notices
1.1 Safety Precautions
Although LCD monitors are displayswith lower voltagethanin the CRTs, the
following precautions still should be take care of.
1) Observe all cautions and safetyrelated notes located inside the displaycabinet and on
the displaychassis.
2) Operation of these displaysoutside the cabinet or with the cover removed involves a
shock hazard from the displaybacklight’s inverter. Work on the displayshould not be
attempted byanyone who is not thoroughlyfamiliarwith precautions necessary when
working on high voltage equipment.
3) Before returninga serviced displayto the customer, a thorough safetytest must be
performed to verifythat the displayis safe to operate without danger ofshock.
1.2Product Safety Notice
1) Manyelectrical and mechanical parts inthischassis provide special visual safety
protection. The protection afforded by them cannot necessarily be obtained by using
replacement components rated for higher voltage, wattage, etc.
2) Before replacing any of these components, read the parts list 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.
1.3 Service Notes
1) When replacing parts or circuit boards, wrap the wires around terminals before
soldering.
2) Keep wires away from high temperature components.
3) Keep cable and their shielding in their original position so as to reduce interference.

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 5
2. Specifications
2.1 Monitor Specification
Power Input
Voltage
Power Consumption
AC 100V to 240 V, 50/60 Hz (External AC Adapter)
LED color is green: < 40 W
LED color is amber: < 5 W
Analog Input
Video Signals
Input Impedance
Sync Signals
Connector
Input Frequency
Resolution (Max.)
Recommended mode
Digital Input
Input Signals
Connector
Input Frequency
Resolution (Max.)
Recommended mode
RGB positive 0.7V p-p
75Ω=(Analog)
Separate, Positive/Negative TTL voltage levels
15 pin Mini D type detachable cable
fH: 31.47kHz ~ 60.02 kHz
fV: 56 Hz ~ 75 Hz
1024 x 768 / 75 Hz
1024 x 768 / 60 Hz
TMDS
DVI-D type
fH: 31.47kHz ~ 48.36 kHz
fV: 75 Hz
1024 x 768 / 60 Hz
1024 x 768 / 60 Hz
Environment
Operating Conditions
Temperature
Relative Humidity
Altitude
Storage Conditions
Temperature
Relative Humidity
Altitude
5℃to 40℃(41℉to 104℉) at altitude 0 ~ 2000m
5℃to 30℃(41℉to 86℉) at altitude 2000 ~ 3000m
20% to 85% (non-condensing)
3000m max.
-20℃to +60℃(-4℉to 140℉)
5% to 95%
10,000m max
Monitor Tilt
Forward
Backward -5º +20º

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 6
Panel Characteristics
Panel Type
Pixel Format
Pixel Pitch
Pixel Configuration
Display Area
Faceplate Coating
Luminance
Contrast Ration
White Point
Display Color
Viewing Angle
15-in (38.1 cm) XGA TFT LCD (active matrix)
1024(H) x 768(V) (1 pixel = R+G+B dot)
0.297 mm(H) x 0.297 mm(V)
R、G、B vertical stripe
304.1 mm(H) x 228.1 mm(V)
Anti-glare, and hard-coating 3H (Haze value = 28)
300 Cd/m² (typ.)
500:1 (typ.)
(x, y) = (0.29, 0.31)
16,777,216
H: -65º ~ 65º (typ.)
V: -60º ~ 50º (typ.)
Panel Characteristics DDC2B
Power Management Complies with EPAand DPMS
Dimension 376 mm x 381 mm x 204 mm (W x H x D)
Weight 5.5 kg
2.2 Stereo Speakers
1) Impedance: 8 ohms
2) Input power: 1.2 Watts RMS (maximum) X 2
3) Input jack: stereo 1/8-inch mini-jack input
Stereo
Speaker

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 7
2.3Timing Supported – Analog Inputs
Mode Resolution fH(kHz) fV(Hz) Pixel Clock (MHz) H pol. V pol..
1 640 x 350 31.47 70.09 25.18 + -
2 640 x 480 31.47 59.94 25.18 --
3 640 x 480 37.80 72.81 31.50 --
4 640 x 480 37.50 75.00 31.50 --
5 800 x 600 35.16 56.25 36.00 + +
6 800 x 600 37.88 60.32 40.00 + +
7 800 x 600 48.08 72.19 50.00 + +
8 800 x 600 46.88 75.00 49.50 + +
9 1024 x 768 48.36 60.00 65.00 --
10 1024 x 768 56.48 70.07 75.00 --
11 1024 x 768 60.02 75.03 78.75 + +
12 720 x 400 31.47 70.08 28.32 - +
13 640 x 480 35.00 66.67 30.24 --
14 832 x 624 49.73 74.55 57.28 --
2.4Timing Supported – Digital Inputs
Mode Resolution fH(kHz) fV(Hz) Pixel Clock (MHz) H pol. V pol..
1 640 x 480 31.469 59.940 25.175 --
2 640 x 480 37.50 75.00 31.50 --
3 800 x 600 37.88 60.3 40.00 + +
4 800 x 600 46.88 75.00 49.50 + +
5 1024 x 768 48.363 60.004 65.000 --

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 8
3. Control Buttons and Functions
3.1 User Control Buttons
There is a power button located at the lower center of the front panel, as well as an LED
for power status indication as shown below.
Also there are three control buttons, i.e., “Select”, “Left” and the “Right” on the front
panel of the display as shown below.
And the associated functions of these keysare described as follows:
Power Button LED
Left Button
Select Button
Right Button

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 9
Key Function Description
POWER Push to turn on or turn off the display. The power indicator
(Green) will light while the display is on.
Select Display the main On-Screen Display (OSD) window and
select options in the windows.
Right Move forward through the choice in the OSD windows. If a
n
adjustment bar is displayed, this button increases the setting.
Left Move backward through the choice in the OSD windows. If
an adjustment bar is displayed, this button decreases the
setting.
3.2 Power LED
The color of the power LED depends on the power status of the monitor. When the LED
color is continuously green, it indicates the monitor is at normal operation state. When the
LED is in amber, it indicates the monitor is at a power saving state.
3.3 Tilting the Display
CML155XW has a tilt feature that allows you to tilt the displayback and forth or swivel
the display left and right to find the most comfortable viewing position. To tilt the display,
grasp the sides and push the display back or pull it toward you until it is in the desired
position. The display can be tilted 20º backward and 5º forward or swiveled 60º left and
right.
Note: Do not tilt thedisplay by grasping the top edge.
Grasp here
to tilt

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 10
4. Disassembly Instructions
To disassembly the monitor, follow the steps as below:
1)Face Down the Monitor.
Note: Place the monitor face down ona smooth surface covered by soft material to
protect the panel faceplate.
2)Back Cover Removal:
In Fig. 4-1, remove 4 screws indicated as “A” from the four corner of the back cover. Then
remove the back cover.
3)Metallic Cover Removal:
In Fig. 4-2, remove 7 screws indicated as “B” from the back metallic cover. Then remove
the back metallic cover.
A
Fig. 4-1
B
Fig. 4-2

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 11
4)PCB Assembly Removal:
Caution: When serving or replacing the panel, disconnect the DC power jack completely.
(a) Unplug all connected wires from the PCB.
(b)Remove 3 screws indicated as “C” from the inverter board, and then remove the board
carefully. (left side in Fig. 4-3)
(c) Remove 3 screws indicated as “D” from the audio board, and then remove the board
carefully.
(d)Remove 7 screws indicated as “E” from the main board connected with front cover. (Fig.
4-3)
5)Panel Removal:
(a) Remove 6 screws indicated as “F” from the front cover (Fig. 4-3) to remove the panel.
C
Fig. 4-3 DF
E

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 12
5. General Connection and Applications
Procedures for installing and using this CML155XW LCD monitor are described as
below.
5.1Connecting the monitor to acomputer
1) Place the display on a flat, sturdy surface. Choose an area free from excessive heat,
moisture, and sunlight. Avoid possible sources of electromagnetic interference, such as
transformers, motors, and fluorescent lighting.
2) Locate the AC power adapter with attached power cable and then connect the power cable
to the power jack on the back of the display. Plug the three-prong power cord into a power
outlet, and plug the other end into the AC power adapter. The three-prong power cord is a
shielded type and is provided as a safety precautions to ensure proper electrical grounding.
3) Plug the D-SUB 15-pin analog video signal cable (or 20-pin DFP cable) into the Analog
(or Digital) Video Input port on the back of the display. Connect the other end of the video
cable into your computer’s video port. The assignment of the pins of the connector is as
follows:
Analog video
input port
Digital video
input port
Power jack

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 13
Pin Assignment of 15-pin D-SUB connector
1Red Video 9+5V for DDC circuit
2Green Video 10 Logic Ground
3Blue Video 11 Monitor Ground
4Monitor Ground 12 DDC-Serial Data
5DDC-Return 13 H-Sync.
6Red Ground 14 V-Sync.
7Green Ground 15 DDC-Serial Clock
8Blue Ground
Pin Assignment of 24-pin DVI-D connector
1T.M.D.S. Data2- 13 T.M.D.S. Data3+
2T.M.D.S. Data2+ 14 +5V Power
3T.M.D.S. Data2/4 Shield 15 Ground (for +5V)
4T.M.D.S. Data4- 16 Hot Plug Detect
5T.M.D.S. Data4+ 17 T.M.D.S. Data0-
6DDC Clock 18 T.M.D.S. Data0+
7DDC Data 19 T.M.D.S. Data0/5 Shield
8No Connect 20 T.M.D.S. Data5-
9T.M.D.S. Data1- 21 T.M.D.S. Data5+
10 T.M.D.S. Data1+ 22 T.M.D.S. Clock Shield
11 T.M.D.S. Data1/3 Shield 23 T.M.D.S. Clock+
12 T.M.D.S. Data3- 24 T.M.D.S. Clock-
4) Connect the audio cable to the speaker input jack on the back of the display (the jack is
colored green to match the cable plug and the writed audio 1):

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 14
5) First turn the PC power switch ON. Then apply power to the display by pressing the power
button to turn the monitor on. The power indicator LED will then illuminate.
Note: Do not forcethe cable into the connector; line it up carefully so that you don’t
bend the pins.
5.2Connecting the monitor to an AVdevice
1) Plug the 4-pin s-video signal cable (or CVBS cable) into the S-video (or CVBS) Video
Input port on the back of the display. Connect the other end of the video cable into your
AV’s video port. The assignment of the pins of the connector is as follows:
Audio 1 jack
S-video video
input port
CVBS video
input port
Power jack

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 15
Pin Assignment of 4-pin mini-din connector
1GND 3Y_in
2GND 4C_in
2) Connect the audio cable to the speaker input jack on the back ofthe display(labeled
audio 2):
Audio 2 jack

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 16
6. Electronic Circuit Description
The block diagram of CML155XW LCD monitor is shown in Appendix A.
6.1 Main Board Circuit
The circuit diagrams of main board are shown in Appendix Band the circuit diagrams of
audio board, keyboard and inverter are shown in Appendix C, D and E, respectively.
(1) Analog Interface
Refer to circuit diagram titled ‘Input Connector’ in Appendix B.
I. The analog R, G, B video input signals are supplied through the cable which is
terminated at P009 (i.e. CONNECTOR DB15). These input signals are approximately
0.7VPP in amplitude.
These and other signals which terminated at P009 are protected byD010~D015 (i.e.
HSK120) from electrostaticdischarge (ESD) damage.
These R, G, B video signals are AC coupled via 0.01uF capacitors C244, C233 and
C226 and buffered via 100 ohm resisters R076, R069 and R067, and then fed into
I011:1 (i.e. GM5020) at pin E1, pin D2 and pinC1 respectively.
These analog R, G and B video signals are converted to their digital forms in I011:1.
II. The HSYNC and VSYNC signals are of TTL level in amplitude and also protected by
D016~D019 (i.e. HSK120). The protected version of these two signals are buffered via
I021 (i.e. 74HCT14D) and then fedinto I011:1 at pin L2 and pin K1.
III. The signals terminated at P009 pin 12 and pin15 are protected byD006~D009
(i.e. HSK120) and then connected to I014 (i.e. 24WC02).
I014 stores the EDIDdata that serves for the purpose of plug-and-play(P&P)
functionality.
The supplyvoltage of I014 (i.e., VCC at pin 8) is eitherfrom P009 pin 9 while
CML155XW V is powered off (the power plug of AC adapter is completely
disconnected from the powerjack ofCML155XW V) or from 5V source.
(2) Digital Interface
Refer to circuit diagram titled ‘Input Connector’ in Appendix B.
I. The TMDS LVDS (Low Voltage Differential Signal) input data pairs of digital R, G,
and B signals are supplied through the cable which is terminated at P008 (i.e. 74320-
4004) pin 18, 17, pin 10, 9 and pin 2, 1. and theyare fed into I011:1 at pin C8, D8,
pin C9, D9, and pinC10, D10 respectively.
II. Also there is a pair ofLVDS clock signals from pin 23 and 24 at P008 and fed into
I011:1 at pin C6 and D6.
III. The signals DDC/SCLand DDC/SDA terminated at P008 pin 6 and pin 7 areconnected
to I013 (i.e. 24WC02). I013 stores the EDIDdatathat serves

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 17
for the purpose of plug-and-play (P&P) functionality. The power supply of I013 is
from pin 14 (labeled DDC+5VDC) ofP008.
(3) Memory Interface
Referto circuit diagram titled ‘Frame Store’in Appendix B.
There are three SDRAMs I015, I017, and I018 which provide the functionalityof frame-
rate conversion..
(4) Output Interface
Referto circuit diagramtitled ‘OUTPUT INTERFACE ’)in Appendix B
There are 8-bit even and 8-bit odd signals for each R, G,Bchannels from I011:2 (i.e.
GM5020) that totally48-bit dataare fed into P010 and P011 via resistor buffers. Also
there are another 4 control signals that are fed into P010: CLK, DE, VS and HS (at pin 44,
42, 40, and 38 ofP010 respectively).
(5) Microcontroller
Referto circuit diagramtitled ‘Host’in Appendix B.
I. The Microcontroller I006 (TS87C51RD2-MCB)is running with the clock based on
20MHz crystal X001. Pin 35 of I006 (/EA1) is pulled-up to +5 volt via resistor to force
I006 read/write memoryinternally.Itis important that pin 35 of I006 shall be so
pulled up for its proper operation and I002 (i.e. HT7044A provide reset signal for I006
reset signal for I006.
There is an interrupt signalcomes from I011:5 pin R3 (IRQn) and is fed in to pin 14
of I006 (INT0).
The signal designated VGA_CON (pin R4 of I011:5) is used for the determination of
whether the analog signal video cable is connected to P009 or not. And the signal
designated DVI_CON (pin L1of I011:5) is used for the determination of whether the
digital video signal cable is connected to P008 or not.
The signals designated HDATA0~HDATA3, HCLKand HFSn (between pin 2 ~ 7 of
I006 and pin R2, R1, P4, P3, P1 and P2 of I011:5) are used for the command and
data transfer between these two ICs.
The signal from pin 17 (P3.5) of I006 is the control signal for I003 (24LC16B ). And
the signal between pin 16 (P3.4) of I006 and pin 5 (SDA) ofI003 is a bi-directional
data channel.
The signals designated KEY UP, KEY DOWN, KEY SEL, KEY ON/OFF between
I006 and P006 serve as user key command scan and sense. P0.6 and P0.7 of I006
controls the conduction and cut-off of transistors Q003 and Q002 to light the LEDs.
The signals designated VOLUME, AUDIO MUTE, and AUDIO SELECT between
I006 and P004 are used for audio board control.
The signal designated VOLUME_PWM is used for the volume of audio control. The
1“/EA” means EA signal is active “low”.

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 18
BKLT_PWM is used as backlight brightness control. BKLT_EN controls the
backlight’s on/off.And LCD_ON/OFF is used for turning on or off the LCD panel.
(6) Power
Referto circuit diagramtitled ‘POWER’in Appendix B.
The DC +12V output of AC adapter is fed into the monitor through P002. This supply is
regulated by I009 and I012 to provide +5V for the whole system. And the +5V supply is
fed into I016, I005, I007, and I008 to provide multiple 3.3V and 2.5V supplies. The +12V
also is fed into I001 to provide 5.0V independentfor video decoder chip.
6.2 Audio Board Circuit
The circuit diagrams of audio board circuit is shown in Appendix C.
6.3 Keyboard Circuit
The circuit diagrams of keyboard circuit is shown in Appendix D.
6.4 Inverter Circuit
The circuit diagrams of inverter is shown in Appendix E. The inverter supplies power for
backlight for the LCD panel.

HITACHI CML155XWLCDMonitor Service Manual (v1.0) 19
7. Troubleshooting Flow Chart
For troubleshootingthe monitor, pleaserefer to “troubleshooting flow chart” in Appendix F.
8 Proposed RepairParts List
For proposed repair parts list please refers to the Appendix G.
9. Mechanical Disassembly
For mechanical disassembly,please refer toAppendixH.
.
10.PCB Layout
For PCB layout diagrams, pleaserefer to Appendix I.