LITE-ON EC150AT Service Manual

Service Manual

15-inch LCD Monitor
EC150ATA

EC-150ATA

Table of Contents

1. Audio circuit --------------------------------------------------------------------------------------------------------------- 1

1.1 Audio input ------------------------------------------------------------------------------------------------------------ 1

1.2 Audio output ---------------------------------------------------------------------------------------------------------- 1

2. Power supply -------------------------------------------------------------------------------------------------------------- 1

3. On-screen circuit ---------------------------------------------------------------------------------------------------------- 1

4. Video input circuit -------------------------------------------------------------------------------------------------------- 1

5. Definition converter LSI peripheral circuit ---------------------------------------------------------------------------- 1

6. System reset, LED control circuit --------------------------------------------------------------------------------------- 2

7. E2PROM for PNP --------------------------------------------------------------------------------------------------------- 2

8. E2PROM -------------------------------------------------------------------------------------------------------------------- 2

9. CPU circuit ----------------------------------------------------------------------------------------------------------------- 2

9.1 Dection of POWER switch status ---------------------------------------------------------------------------------- 2

9.2 Display mode identification ----------------------------------------------------------------------------------------- 2

9.3 User control ----------------------------------------------------------------------------------------------------------- 4

9.4 Control of identification converter LSI (IC 14) ------------------------------------------------------------------ 5

9.5 I2C bus control -------------------------------------------------------------------------------------------------------- 5

9.6 Power ON sequence -------------------------------------------------------------------------------------------------- 6

9.7 Power OFF sequence ------------------------------------------------------------------------------------------------- 7

9.8 List of CPU assignments--------------------------------------------------------------------------------------------- 8

10. Inverter Protective circuit for back light ------------------------------------------------------------------------------- 9

11. USB circuit -----------------------------------------------------------------------------------------------------------------9

11.1 3.3V cutoff circuit for USB identification ----------------------------------------------------------------------- 9

11.2 USB hub control circuit -------------------------------------------------------------------------------------------- 9

11.1 Lower port circuit --------------------------------------------------------------------------------------------------- 9

11.1 DC/DC converter circuit ------------------------------------------------------------------------------------------------- 9

IndexCircuit Description

EC-150ATA

1. Audio circuit (Circuit diagrams Main PWB 1/1 JACK PWB 1/1)

1.1 Audio input
The audio signal input received from the audio input terminal (JK011) is applied to the pre-amplifier I006 of 2
(L-CH) and 3 (R-CH) through the low-pass filter consisting of R047, R049, R048, R050, C013 and C014.
In this pre-amplifier, controls of Volume, Balance, Bass, and Treble are conducted. The audio signal controlled
at the pre-amplifier is entered in and amplified at the AMF I007 of 2 (L-CH) and 1 (R-CH). Since then, the signal
is output to the jack board through a cable.

1.2 Audio output
The audio signal is output from the head-phone output terminal (JK001) of the jack board to the speaker system
or the head-phone.
When the stereo mini-plug is inserted in the head-phone output terminal, output from the speaker is suspended,
but the audio signal attenuated by resistors R001 and R002 is output to the stereo mini-plug side.

2. Power supply (Circuit daigrams MAIN PWB 7/8)

1. I314:DC-DC converter
A 5V power supply for LCD module, CPU, and logic is generated from the 12V source.

2. I315:3-terminal regulator
A 3.3V power supply for LCD module is generated from the 5V source.

3. I315:3-terminal regulator
A 3.3V power supply for I317 analog is generated from the 5V source.

4. I315:3-terminal regulator
A 3.3V power supply for I317 digital is generated from the 5V source.

Q303, I312 ON/OFF control for LCD Module
ON/OFF control is performed for power ON/OFF and also for the power saving sequence.

3. On-screen circuit (Circuit diagrams Main PWB 3/8)

I310 (MTV130P-30) is an OSD IC.
The HREF Signal, the OSDVS signal (horizontal / vertical sync signal in negative polarity), and the OSDTCLK
signal (dot clock for OSD display) are received from I317 (Circuit diagram MAIN PWB 3/8 gmZAN1), and the
OSD functions controlled by IIC interface (pin 7, pin 8).
Using these data, and On-screen menu screen is established and the resultant data are output to I317 (Circuit
diagram MAIN PWB 3/8, gmZAN1).

4. Video input circuit (Circuit diagram MAIN PWB 4/8)

The AC-coupled video signal is used to clamp the black level at 0V).

5. Definition converter LSI peripheral circuit (Circuit diagram MAIN PWB)

I317 gmZAN1 is the definition converter LSI.
The analog R, G, B signal input entered from the video input circuit is converted into the digital data of video
signal through the incorporated A/D converter. Based on this conversion, this device performs interpolation
during pixel extension. The source voltage for this device is 3.3V and the system clock frequency is 50MHz.
The withstand voltage level for the input signal voltage if I317 is 3.3V and 5V.

Page 1Circuit Description

EC-150ATA

6. System reset, LED control circuit (Circuit diagram MAIN PWB 2/8, 3/8)

6.1 System reset
System reset is performed by detecting the rising and falling of the 5V source voltage at I301.

6.2 LED control circuit
Green / amber is lit with the control signal of the LED GREEN and LED AMBER signal pin 15, 12 from I307
(Circuit diagram MAIN PWB 2/8).

7. E2PROM for PnP (Circuit diagram MAIN PWB 2/8)

8. E2PROM (Circuit diagram MAIN PWB 2/8)

Data transfer between I305 (AT24 C16) and CPU (Circuit diagram MAIN PWB 2/8 (I302) is effected through
the IIC bus SCL (pin 15) and SDA (pin 16) of I302. The data to be transferred to each device are stored in I305.

l I317 control data.
l OSD related setting data.
l Other control data for service menu.

9. CPU circuit (Circuit diagram MAIN PWB 2/8)

I302 (80C51RA2) functions as the CPU.
The source voltage for the device is 5.0V and the system clock frequency is 20MHz.

9.1 Detection of POWER switch status
The CPU identifies the ON status of the two power supplies. The identification is made when the power supply
is turned off. For example, if the power supply is turned off with the POWER switch, the POWER switch must be
turned on when activating the power supply again. If the power supply is turned off by pulling out the power
cord, then this power supply can be turned on by connecting the power cord, without pressing the POWER
switch.

9.2 Display mode identification

9.2.1 Functions
(1) Display mode identification

l The display mode of input signal is identified based on Table 1, and according to the frequency and polarity

(HPOL, VPOL) of horizontal or vertical sync signal, presence of the horizontal or vertical sync signal, and the
discrimination signal (HSYNC_DETECT, VSYNC_DETECT).

l In MOD [3] [4], inappropriate polarity, composite sync, and sync ON green are indentified as MOD [4].
l When the mode has been identified through the measurement of horizontal and vertical frequencies, the total

number of lines is determined with a formula of  Horizontal frequency / Vertical frequency = Total number
of lines. Final identification can be made by examining the coincidence of the obtained figure with the
number of lines for the mode identified from the frequency. The boundary number of lines in each mode is
shown in Table 2.

l When the detected frequency if the sync signal has changed, the total number of lines should be counted even

through it is rge identified frequency in the same mode. Then, it is necessary to examine whether the preset
value for the vertical display position of Item 4-3 has exceeded the total number of lines. If exceeded, a

maximum value should be set up, which does not exceed the vertical display position of Item 4-3.
(2) Power save mode.
This power save mode is assumed when the frequency of the horizontal / vertical signal is as specified below.

l Vertical frequency : Below 24 KHz
l Horizontal frequency : 75 KHz or above,
l VTOTAL : 1027 or more.

Page 2 Circuit Description

EC-150ATA

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)

(3) Asset management
As an action for asset management, the potential at the WRITE PROTECT pin is turned to be H if there is a
vertical input of vertical frequency (42 Hz +/- 1 Hz),
For more detailed setting method, refer to 4-6-5-14 (8). During this operation, this system stays in the Out-Of­Range mode.
(4) Power save mode.
The power save mode is assumed when the horizontal / vertical signals are as specified below.

l If there is no horizontal sync signal input.
l If there is no vertical sync signal input.
l If the horizontal sync signal is outside the measuring range of gmZAN1.
l If the vertical sync signal is outside the measuring range of gmZAN1.

Table 1

Signal

Preset Mode HSYNC: Frequency VSYNC:

No.

1 640 x 400 (56)24 KHz < fH < 30.8 KHz 21.053 24.830 56.432

2 640 x 480 (60)30.8 KHz < fH < 33 KHz FV < 63 Hz 25.175 31.469 59.992

3 720 x 350 (70

4 720 x 400 (70

4 720 x 400 (70

5 800 x 600 (56)33 KHz < fH < 43 KHz FV < 58 Hz 36.000 35.156 56.250

6 800 x 600 (60

7 640 x 480 (66

8 640 x 480 (72

9 640 x 480 (75

10 720 x 350 (85

11 720 x 400 (85

11 720 x 400 (85

12 800 x 600 (75)43 KHz < fFH < 47.2 KHz FV < 80 Hz 49.500 46.875 75.000

13 640 x 480 (85

14 1024 x 768 (60)47.2 KHz < fH < 51 KHz FV < 63 Hz 65.000 48.363 60.004

15 800 x 600 (72

16 832 x 624 (75

14 1024 x 768 (60)51 KHz < fH < 55 KHz FV < 70 Hz 70.490 52.448 60.004

17 800 x 600 (85

18 1024 x 768 (70)55 KHz < fH < 59 KHz 75.000 56.476 70.069

19 1024 x 768 (75)59 KHz < fH < 62 KHz 78.750 60.023 75.029

20 1024 x 768 (85)62 KHz < fH < 75 KHz 94.500 68.677 84.977

Fre

uenc

58 KHz < fV<
63 KHz
63 KHz < fV<
68 KHz
68 KHz < fV<
74 KHz
74 KHz < fV SEP - - 31.500 37.500 75.000

80 Hz < fV 36.000 43.269 85.008

63 Hz < fV <
73 Hz
73 Hz < fV 57.283 49.725 74.550

70 Hz < fV 56.250 53.674 85.061

SYNC

HSYNC:

TYPE

OTHER OTHER OTHER

OTHER OTHER OTHER

Polarit

SEP + - 25.175 31.469 70.087

SEP - + 25.175 31.469 70.087

SEP + - 31.500 37.861 85.080

SEP - + 31.500 37.861 85.080

VSYNC:

Polarit

DOTCLK fH(KHz)FV (Hz

40.000 37.879 60.317

30.240 35.000 66.611

31.500 37.861 72.809

50.000 48.077 72.188

Page 3Circuit Description

Table 2 the number of the lines, Vsync distinction

EC-150ATA

Indication resolution The number of the

distinction lines

The mode of 400 line and

under

640 x 480 487 < LINE < 607 fV < 63 Hz 6

800 x 600 607 < LINE < 777 fV < 58 Hz 11

832 x 624 640 < LINE -16

1024 x 768 768 < LINE < 870 fV < 63 Hz 17

1152 x 864 870 < LINE < 1031 UN SUPPORT
1280 x 960 960 < LINE < 1027 UN SUPPORT

1280 x 1024 1027 < LINE UN SUPPORT

LINE < 487 fV < 63 Hz 3

Distinction Vsync The fixed mode

63 Hz < fV < 78 Hz 1

78 Hz < fV 11

63 Hz < fV < 68 Hz 7
68 Hz < fV < 74 Hz 8
74 Hz < fV < 78 Hz 9

78 Hz < fV 10

58 Hz < fV < 63 Hz 12
63 Hz < fV < 73 Hz 14
73 Hz < fV < 78 Hz 13

78 Hz < fV 15

63 Hz < fV < 68 Hz 18
68 Hz < fV < 73 Hz 19
73 Hz < fV < 78 Hz 20

78 Hz < fV 21

Attention :

1. Make it the mode 16 by the first HSYNC, the VSYNC distinction in the time beyond 640 line when you

recognize it with the mode 16.

2. When resolution beyond 1024 x 768 is inputted, resolution is lowered with Down scaling to 1024 x 768, and

indicated, and OSD should indicate OUT of Range.

9.3 User Control

9.3.1 Related ports of I317

Port Pin No. I/O Signal name Function Remarks

MFB1 112 1 RESET RESET switch input The set value is

returned to the
initial value

MFB5 107 1 EXIT EXIT switch input Withdraw from

OSD

MFB10 124 1 DOWN switch input ( ) key

MFB4 109 1 UP switch input ( ) key

MFB11 123 1 - switch input ( ) key

MFB3 110 1 + switch input ( ) key
MFB2 111 1 PROCEED PROCEED switch input Functional

Page 4 Circuit Description

EC-150ATA

9.3.2 Functions
Control is effected for the push-switches to be used when the user changes the parameters, in order to modify the
respective setting values. Whether the switch has been pressed is identified with the switch input level that is
turned L.
Each switch input port is pulled up at outside of ASIC.
Each parameter is stored in the EEPROM, the contents of which are updated as required.

9.4 Control of definition converter LSI I317

9.4.1 Ports related to control

Pin No. I/O Signal name Function

101 I IRQ gmZan1 interrupt signal
103 O HCLK gmZan1 serial clock

99 I/O HDATA gmZan1 serial data
98 O HFS gmZan1 serial select

9.4.2 Functions
Major function of I317 are as follows:
(1) Expansion of the display screen.
(2) Timing control for various signal types.
(3) Power-supply sequence (LCD panel).

9.5 I2C bus control

9.5.1 Related ports of I201

Port Pin No. I/O Signal name Function
P3.3 15 I IICCLK IIC bus clock

P3.4 16 I/O IICDATA IIC bus data

9.5.2 I2C-controlled functions
The following functional controls are effected by I2C.
(1) Control of EEPROM I305f for parameter setting.
(2) Control of audio preamplifier.

Page 5Circuit Description

EC-150ATA

9.6 Power ON sequence
When the POWER switch is pressed, the POWER OFF signal is turned H. When this H potential is detected,
the CPU begins to establish the respective power supplies according to the sequence shown below.

POWER

PPWR

DOTCLK

USBSW

UCPB IAS

LVC C

LED

DATA

Page 6 Circuit Description

EC-150ATA

9.7 Power OFF sequence
When the POWER switch is pressed while the power supply is ON, the POWER ON signal is turned H. When

this H potential is detected, the CPU begins to turn off the respective power supplies according to the sequence
shown below.

POWER

PPWR

DOTCLK

USBSW

UCPB IAS

LVC C

LED

DATA

Page 7Circuit Description

9.8 List of CPU Pin Assignments

g

)

Port Pin No. Signal Name Initial Setting Function Remark

EC-150ATA

~
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.9

~

P3.0

~
P3.1
P3.2
P3.3
P3.4
P3.5
P3.6
P3.7

~

~

~

~
P2.0
P2.1
P2.2
P2.3
P2.4
P2.5
P2.6
P2.7

~

~

~

~
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0

~

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

D4(LEDAMBER

40

41

42

43

44

NC ~ ~
HDATA0 ~ gmZAN1 4bit interface data
HDATA1 ~ gmZAN1 4bit interface data
HDATA2 ~ gmZAN1 4bit interface data
HDATA3 ~ gmZAN1 4bit interface data

HCLK ~

HFS ~ gmZAN1 data enable

VOL_OUT H reserved

PWM ~ Pulse width modulation

RST L Reset CPU Active H

RXD H Receive data

NC ~ ~

TXD H Transmit data

IRQ ~ gmZAN1 interrupt signal
SCL ~ IIC Bus Clock

SDA H IIC Bus Data

DDC-GND L Detect Dsub cable plug-in Active L

P3.6 H External Memory Write Enable
P3.7 H External Memory Read Enable

XTAL2 ~ Crystal signal out

XTAL ~ Crystal signal in

GND ~ ~

NC ~ ~

A8 ~ High-order address byte

A9 ~ High-order address byte

A10 ~ High-order address byte
A11 ~ High-order address byte
A12 ~ High-order address byte
A13 ~ High-order address byte
A14 ~ High-order address byte
A15 ~ High-order address byte

PSEN# H Program store enable

ALE ~ Address latch enable

NC ~ ~

EA# H External Access Enable

D7(USB_ON) H USB HUB power Enable

D6(Uc-PBIAS) H Inverter power Enable

D5(LEDGRN) H LED Green ON

L LED AMBER ON
D3 ~ reserved
D2 ~ reserved

D1(MUTE) L Audio MUTE Enable

D0(AU_SUSP) H Audio SUSP Enable

VCC ~ VCC

mZAN1 4bit interface Clock

Page 8 Circuit Description

EC-150ATA

10. Inverter Protective curcuit for back light and power source circuity (Circuit diagram MAIN
PWB 8/10)

This unit operates on an output voltage of 12V from AC adapter. When an AC adapter with an output voltahe
over 12V higher is connected, the control signal from I101 is forcibly connected to the LOW level through D101
(RLZ18B), Q101 (SST33904), and R101, R102. In order to protect the inverter for back light. By this treatment,
oscillation is suspended in the inverter circuit. It must be noted that the back light it unlit as a result of the
stoppage of inverter oscillation.

11. USB circuit

11.1 3.3V cutoff circuit for USB identification (Circuit diagram USB PWB 1/4)
Q905 is a composite transistor where one PNP and one NPN are incorporated in a package.
A signal at pin 1 (5V) of USB (B) connector CN901 passes through R975 (33 ohm) and enters pin 4 (TR2B) of
Q905. Pin 4 is an NPN type base of the internal transistor in Q905. the collector (pin 3) is connected to a 3.3V
circuit through R974 (10 ohm) and R972 (10 ohm) connected in series. The emitter (pin 2) is connected to GND.
For the PNP transistor, on the other hand, a voltage-divided power from the 3.3V circuit is fed to the base (pin 5)
and the collector (pin 1) is connected to UD+ of the USB data line through R901 (1.5 ohm). The emitter (pin 6)
is connected to the 3.3V circuit.
When the USB connector is connected and voltage at pin 1 of CN901 attains 5V, the NPN transistor of Q905 is
turned ON. This also turns on the PNP transistor whose base is connected to the collector of the NPN transistor
through R974 (10 ohm). As a result, the DC+ power supply is fed from the 3.3V circuit that is connected to the
emitter of the PNP transistor, through R901 (1.5 ohm) that is connected to the collector.
When the USB connector is pulled out the host computer is turned off, the base voltage of the NPN transistor at
Q905 is turned to be at the GND level, and therefore the transistor is turned off. As a result, a voltage of 3.3V is
applied to the base of the PNP transistor and this causes the PNP transistor to be turned off also. Finally, a voltage
supply of 3.3V is suspended toward UD+.
IC905 is a step-down type series regulator that generates 3.3V from a 5.2V source.

11.2 USB hub control circuit (Circuit diagram USB PWB 2/4)
IC909 is a reset IC, and IC910 is a USB hub control IC made by NEC.
When the monitor power circuit is turned on, a 3.3V power is fed to IC909. Upon the detection of about 2.75V,
IC909 begins to generate a reset signal of 150msec.
IC910 enables communication with a higher port when UD+ and UD- from the USB connector (Circuit diagram
USB PWB 1/4) are applied to pin 7 and pin 8, respectively. Pin 9, 10, 12, 13, 14, 15, 18 and 19 are connected to
the USB connector (Circuit diagran USB PWB 3/4) of the lower port. They function as a communication inter­face between lower and higher ports. If an overcurrent is generated in the lower port, it is transferred to the higher
port.
X901 is a crystal oscillator that supplies a 4MHz clock signal to the USB hub control IC (IC910).

11.3 Lower port circuit (Circuit diagram USB PWB 3/4)
CN904 and 905 are the USB lower-port connector.
The 5.2V output from the DC/DC converter passes through the poly-switches of F901, 902, 903 and 904, and is
led to the power supply pins (pin 1 and pin 5 of each connector) of the USB lower-port connector.
An overcurrent signal is given from the poly-switch - USB lower-port connector line to IC910 (Circuit diagram
overcurrent has been generated in the lower port.

11.4 DC/DC converter circuit (Circuit diagram USB PWB 4/4)
IC906 is a DC/DC converter IC, D903 is a rectifier diode, and L910 is a smoothing coil. Pin 5 (ON / OFF) of
IC906 is connected to pin 5 (S/SW) of the USBDC connector CN903 through transistors Q901 and Q902.
When the potential at pin 5 of CN903 is maintained at the GND level, pin 5 of IC906 is aldo at the gnd level and
IC906 stops generation of its output. When pin 5 of CN903 is at the high level, pin 5 of IC906 then stays in the
OPEN state, this causing IC906 to generate a 5.2V output.

Page 9Circuit Description

EC-150ATA

Table of Contents

1. No display of screen (Screen is black, color of LED is amber) ----------------------------------------------------- 1

2. Nothing displays on screen (Screen is black, color of LED is green) ---------------------------------------------- 2

3. Checking the back light unit --------------------------------------------------------------------------------------------- 5

4. Abnormal screen ---------------------------------------------------------------------------------------------------------- 6

6. Abnormal Auto adjustment ---------------------------------------------------------------------------------------------- 9

7. Abnormal plug and play operation ------------------------------------------------------------------------------------ 10

7.1 Abnormal DDC1----------------------------------------------------------------------------------------------------- 10

7.2 Abnormal DDC2----------------------------------------------------------------------------------------------------- 10

8. Checking the interface circuit of sync signal -------------------------------------------------------------------------11

8.1 Checking the control circuit of horizontal sync pulse ----------------------------------------------------------11

8.2 Checking the control circuit of vertical sync pulse-------------------------------------------------------------- 11

9. Checking the resolution change IC movement -----------------------------------------------------------------------12

10. No power on -------------------------------------------------------------------------------------------------------------- 13

11. Checking the DC/DC converter circuit --------------------------------------------------------------------------------14

12. Checking the operation of CPU ---------------------------------------------------------------------------------------- 15

13. Checking the audio circuit ---------------------------------------------------------------------------------------------- 16

14. Check the USB hub circuit (NEC Version) ---------------------------------------------------------------------------18

14.1 Hub isnt recognize ------------------------------------------------------------------------------------------------ 18

14.2 Connection apparatus isnt recongnize --------------------------------------------------------------------------19

14.3 Connection apparatus doesnt work -----------------------------------------------------------------------------20

14.4 Check the USB IC ------------------------------------------------------------------------------------------------- 21

14.5 Check the power supply -------------------------------------------------------------------------------------------23

15. Check the USB hub circuit (Atmel Version) -------------------------------------------------------------------------25

15.1 Hub isnt recognize ------------------------------------------------------------------------------------------------ 25

15.2 Connection apparatus isnt recongnize --------------------------------------------------------------------------26

15.3 Connection apparatus doesnt work -----------------------------------------------------------------------------27

15.4 Check the USB IC ------------------------------------------------------------------------------------------------- 28

15.5 Check the power supply -------------------------------------------------------------------------------------------29

Trouble Shooting Index

1. No display of screen (Screen is black, color of LED is amber)

Does OSM display when you push

PROCEED button.

Yes

Check if the sync signal from Computer

is output and if the video cable is

connected normally.

No

Preceed "No OSM display"section.

OK

Proceed "Checking the resolution change

IC movement" section.

NG

Input the sync signal of computer, or

change the cable.

When a signal isn't

being inputted, it is

indicated with "VIDEO

INPUT". It is indicated

with "OUT OF RANGE"

at the time of the

frequency that it can't be

distinguished.

EC-150ATA

Trouble Shooting Page 1

2. Nothing displays on screen (Screen is black, color of LED is green)

Is backlight lit?

NG Refer "Checking the backlight unit" section

OK

EC-150ATA

Does computer output RGB video signals?

OK

Check OSM menu is displayed on screen

when you push the "PROCEED" key.

OK

Proceed "Abnormal screen" section.

NG

NG

Check the video cable for failure. Check the host for

output signal with all black only.

1) Change pattern of video signal output on the
host.

2) Reconnect the video cable.

3) Change the video cable.

Check if the LCD video signal cable is connected
between the MAIN PWB and LCD module.

NG

OK

Failure Point

The Cable is disconnected.

Next Page

Page 2 Trouble Shooting