HP R15AAC, R15AAU, vs15 Service Manual

15-inch LCD Monitor
R15AAC/AAU (vs15)

Service Manual

Service Manual Versions and Revision

Copyright

Copyright 2004 LiteOn Technology Corp.
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 LiteOn
Technology Corp.

HP HPD_R15AAC/AAU(vs15) Service Manual.

Printed in Taiwan.

Trademarks

LiteOn is a registered trademark of LiteOn
Technology Corp.

All other trademarks are the property of their
respective owners.

No.VersionRelease DateRevision

1.1.0Dec. 10, 2004Original release

Page 2

R15AAC/AAU (vs15)

1) Power Board Operation Therory

1.Therory of Power Board Operation-----------------------------------------------------------------------------------------4

2) Inverter Circuit

2.Inverter Circuit-----------------------------------------------------------------------------------------------------------------5

3) Interface Operation

3.1 Top---------------------------------------------------------------------------------------------------------------------------6

3.2 Power------------------------------------------------------------------------------------------------------------------------6

3.3 VGA & DDC interface-----------------------------------------------------------------------------------------------------6

3.4 Scaler GM5321-------------------------------------------------------------------------------------------------------------7

3.5 Key & Panel interface-----------------------------------------------------------------------------------------------------8

3.6 Audio------------------------------------------------------------------------------------------------------------------------9

3.7 Others---------------------------------------------------------------------------------------------------------------------10

3.7.1 Detection of POWER switch status--------------------------------------------------------------------------------10

3.7.2 Display mode identification------------------------------------------------------------------------------------------10

3.7.3 List of I/O Pin Assignments of the I311----------------------------------------------------------------------------12

4) Trouble Shooting

1.For Power Board-------------------------------------------------------------------------------------------------------------13

2.For Inverter Board-----------------------------------------------------------------------------------------------------------14

3.No display of screen (Screen is black, color of LED is amber)--------------------------------------------------------15

4.Nothing displays on screen (Screen is black, color of LED is green)------------------------------------------------16

5.Checking the back light unit-----------------------------------------------------------------------------------------------18

6.Abnormal screen-------------------------------------------------------------------------------------------------------------19

6.1 Abnormal screen for VGA source-------------------------------------------------------------------------------------19

7.Abnormal OSM display adjust problem----------------------------------------------------------------------------------20

8.Abnormal plug and play operation---------------------------------------------------------------------------------------21

8.1 Abnormal plug and play operation for VGA-------------------------------------------------------------------------21

Page 3

R15AAC/AAU (vs15)

9.Checking the interface circuit of sync signal----------------------------------------------------------------------------22

9.1 Checking the control circuit of horizontal sync pulse for VGA--------------------------------------------------22

9.2 Checking the control circuit of vertical sync pulse VGA----------------------------------------------------------22

10.Checking the resolution change IC movement--------------------------------------------------------------------------23

11.Audio no signal output-----------------------------------------------------------------------------------------------------24

5) Spare Parts

Recommended Spare Parts List-------------------------------------------------------------------------------------------------26

6) Block Diagram

Block diagram----------------------------------------------------------------------------------------------------------------------27

Page 4

R15AAC/AAU (vs15)

1). Power Board Operation Therory

1.1Line filter consists of C801, T801, C802, C803, C804, C809, C815, C838, R801. It eliminates high frequency interference
to meet EMI’s requirement.

1.2Rec & Filter
Bridge diode D801 converts AC source into pulsed DC. This pulsed DC is smoothed and filtered by C805. R802 is
an NTC ( negative thermal coefficient ) resistor, used to reduce inrush current to be within safe range.

1.3Power transformer :
T802 converts energy for square wave from power source C805 to secondary side to generate +5V, +12V and
+21.5V.

1.4Output :
The square wave from T802 is rectified by D808 D809, D810, then filtered by C818, C824, C829, C813 ,C822 to
generate +21.5V and +12V, +5V respectively.

1.5Driver :
Q803 drive T802 from PWM control of I801 for power converted.

1.6FB :
Negative feedback CKT consists of photo coupler I802 and adjustable regulator I803. It can maintain output
voltages +21.5V and +12V, +5V at a stable level.

1.7PWM :

1.7.1Start : When power is turned on. C807 is charged a 12 volt and a starting current above 1mA to pin 1 of I801.

I801 starts to oscillate and outputs a pulse train through pin 6 to drive Q803.

1.7.2OPP : When Q803 turns on, C805 supplies a linearly increasing triangle current through the primary induc-

tance of T802 to the driver Q803, once the peak value of this current multiplied by R811 exceeds1 volt, pulse
train will be turn off immediately to protect Q803, T802 from being burned out.

1.7.3Regulation : If output voltage +21.5V goes up, the R terminal of I803 gets more bias, accordingly photo

transistor and photo diode flows more current. The voltage of pin 2 goes up too, making the pulse width of
pin 6 to become narrower. So the output voltage +21.5V will be pulled down to a stable value.

1.7.4OVP : If +21.5V goes up too much, the induced voltage on pin 4 of T802 becomes large also. Suppose that it

is over 18 volts. The pulse train at pin 6 goes down to zero, shutting Q803 off immediately.

1.7.5SCP : If output terminal is short to ground, photo transistor does not conduct, hence Q807 does not conduct

either. Then oscillation of I801 is stop, shutting Q803 off immediately.

Line

Filter

Rec. &

Filter

Power

Transformer

Outpur Rec. & Filter

PWM Driver

FB

Power Board Block Diagram

Page 5

R15AAC/AAU (vs15)

2) Inverter Circuit

This unit operates on an output voltage of 21.5V from power source.

2.1VDD: R105 get a +5VDC for I101 power supply.

2.2Control IC: I101 (OZ9930)

2.2.1Enable : When pin 1 of I101 is over 0.55V, I101 works. If it is under 0.55V, I101 turns off.

2.2.2OSC: When I101 enabled, C104/C105 (pin 2 of I101) determine the operating frequency.

2.2.3SST: C106 (pin 1 of I101) provides soft start function.

2.2.4Ignition: IC provides higher operating frequency internally for more striking voltage until regulation of feedback of

lamp current. And provide 2 sec striking time.

2.2.5Dimming control: The divided voltage of R106/R103/R104 control the duty pulse of burst-mode to drive and

perform a wide dimming control for the CCFL. The burst-mode frequency is determined by operating freq/233.

2.2.6Regulation: Pin 8 of I101 provide regulation of the CCFL current from feedback. The non-inverting reference is at

1.25V nominal.

2.2.7Protection: Open-lamp protection in the ignition period is provided through pin 7 of I101.

Removal of the CCFL during normal operation will trigger IC to turns on and shuts off the inverter. This is latch
function.

2.2.8Output drivers: The configuration prevents any shoot-through issue associated with bridge-type power

conversion applications. Adjusting the overlap conduction between Q104, the CCFL current regulation is achieved.

2.3Half-bridge swit ching/Transformer: Q104, C122, C123 compose half-bridge swit ching to convert DC into AC for

driver the CCFL.

2.4Detection: C132, C112, C114, C126, R116, R115, C115 detect the output voltage and ensure a rated voltage by pin7

of I101 ensure not a open-lamp.

2.5Feedback: D116, D117, R111, R112, C109 sense the lamp current for negative feedback and regulation.

Inverter Board Block Diagram

VCC

VDD

Enable

OSC
SST

Output driver

Protection

Ignition

Regulation

Control IC : OZ9930

ON / OFF

Halfl-bridge switching

Transformer

Lamp

Feed back

Detection

VDD

Dimming Control

Brightness

Control

Page 6

R15AAC/AAU (vs15)

3)Interface Operation

3.1Top (Circuit diagrams sheet 2 of 8)

This page is function block. (1) Power. (2) VGA & DDC interface. (3) Scaler GM2621.
(4) Key & panel interface. (5) Audio

3.2Power (Circuit diagrams sheet 3 of 7)

3.2.1P301 connector
A 5V power supply for flash ROM, EEPROM of EDID, logic. It is generated from the
P301 connector.

3.2.2I304 : 3-terminal regulator
A 3.3V power supply for I307 scaler IC gm2621 LCD module, it is generated from the 5V
source.

3.2.3I305 : 3-terminal regulator
A 1.8V power supply for I307 scaler IC gm2621, it is generated from the 3.3V source
(I304).

3.2.4Q302, I301 : ON/OFF control for LCD module power
ON/OFF control (PANELVCC_EN) is performed for power ON/OFF and also for the
power saving sequence. It is support 3.3V to LCD module power. The PANELVCC_EN
signal is generated from I307 scaler IC gm2621.

3.2.5R305: ON/OFF control for LCD module back light power
ON/OFF control (BKLT_EN) is performed for black light power ON/OFF and also for
the power saving sequence. The BKLT_EN signal is generation from I307 scaler IC
gm2621.

3.2.6Q301 : Adjust back light luminance for LCD module
It is adjusted back light luminance control (BKLT_ADJ) is performed for the back light
luminance. The BKLT_ADJ signal is generated from I307 scaler IC gm2621.

3.3VGA & DDC interface (Circuit diagrams sheet 4 of 7)
This sheet have RGB analog video signals input from VGA connector. Select H/V sync signals
source from VGA connector.
The RGB analog video signals input through AC-coupled, analog video signal is used to clamp the
black level at 0V. And H/V sync to sclaer.
And support DDC plug & play function for analog video.

3.3.1P302 connector

The RGB analog video input signals from the P302 connector.

3.3.2I306 DDC EEPROM

This IC is support DDC2B of the VESA standard, also plug and play for the PC host.

Page 7

R15AAC/AAU (vs15)

3.4Scaler gm2621 (Circuit diagrams sheet 5 of 7)
The I307 gm2621 is all-in-one LCD monitor controller. The gm2621 leverages Genesis patented
advanced image-processing technology as well as a proven integrated ADC/PLL. Gm2621 also
integrates a micro-controller, an OSD controller, and dual LVDS.
The RGB analog video signal input entered from the video input circuit is converted into the digital
data of analog video signal through the incorporated A/D converter.
Based on this conversion, this device performs interpolation during pixel extension. These interpo­lation digital data are transformed to LVDS signal. The I307 source voltage is 3.3V and 1.8V, the
device clock source frequency is 14.318 MHz. And support keypad function.

3.4.1I310 SPI Flash ROM

The firmware program running from I310 external ROM, contains firmware code and data
for all firmware function, and control data and parameter and OSD related setting and other
service data. The device is 8bit configuration, 1024K bytes of ROM.

3.4.2I308 Microprocessor Supervisory Circuit

The function of this device is to assert a reset to I307 scaler gm2621, if either the power
supply dropped down.

3.4.3X301 14.318MHz

It generated reference clock input for I311 scaler.

3.4.4ISP and DDC2Bi function

The DDC2Bi is VESA standard for the host PC system, it can through DDC2Bi bus control
LCD monitor. Enter I307 pin54 DDC_SCL and pin55 DDC_SDA of the VGA port.
It use ISP function when change new firmware to I310 flash ROM. It used DDC2B port
IIC bus through I307 gm2621 to I310 flash ROM.

3.4.5The power save sequence function

First disable I307 pin49 (BKLT_EN) from H to L of LCD module back light power, delay
some time, then disable I307 pin127 (PANELVCC_EN) from H to L of LCD module
power, then I307 enter to power down mode.

Page 8

R15AAC/AAU (vs15)

3.5Key & Panel interface (Circuit diagrams sheet 6of 7)

3.5.1P306 connector
It is LVDS bus, it is from I307 scaler to LCD panel module. The output voltage is 3.3V.

3.5.2P307 connector
The P307 has support keypad function. Control is give effect to for the push switch 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 inputs a
DC voltage into I107 pin113 (LBADC_IN3) and pin114 (LBAD1_IN2).
Each switch input voltage based on Table 1.
Each parameter is stored in the I310 EEPROM, the contents of which are updated as
required.
The P307 have LED Blue and Amber light, the LED Blue signal from I307 pin 51, and the
LED Amber signal from I307 pin 56.

Table 1 Related ports of I311

Pin No. I/O Signal name Function Remarks Voltage

Pin 114 I KEY_POWER Soft power switch

input

Power key 1.05V

LBADC_

IN2

Pin 114 I KEY_MENU Enter OSD switch

input

Enter OSD menu 1.69V

Pin 113 I KEY_UP switch input Up key or

Source 2

2.3V

Pin 113 I KEY_DOWN

switch input Down key or

Source 1

1.9V

LBADC_

IN3

Pin 113 I KEY_SELECT Selection switch

input

Select key or

Auto adjust key

1.57V

↑

↓

Page 9

R15AAC/AAU (vs15)

3.6Audio (Circuit diagrams sheet 7 of 7)

3.6.1P307 connector
The P307 is audio signal input from the keypad function board.

3.6.2P308 connector
The P308 have two audio function signals. One is audio volume control from the keypad
function board. Other is audio output to speaker or ear phone-jack.

3.6.3I312 TDA74965A
The I312 is 5x5W stereo audio amplifier, it is an integrated class-B dual output amplifier.

3.6.4Q308, I313: ON/OFF control for Audio power
ON/OFF control (AUDIO_PW) is performed for power ON/OFF and also for the audio
power down sequence. It is support 12V to audio power. The AUDIO_PW signal is
generated from I307 scaler IC gm2621.

3.6.5R385, Q309: MUTE control for Audio
MUTE control (MUTE) is performed for audio return to mute and also for the audio power
down sequence. The MUTE signal is generated from I307 scaler IC gm2621.

Page 10

R15AAC/AAU (vs15)

3.7Others

3.7.1Detection of POWER switch status
The I307 gm2621 identifies the ON status of the two power supplies. The identification is
made when the power supply is turn off. For example, if the power supply is turn off with
the POWER switch, the POWER switch must be turn on when active 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.

3.7.2Display mode identification

3.7.2.1Display mode identification
The display mode of input signal is identified based on Table 2.

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 “Hori-
zontal frequency / Vertical frequency = Total number of 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 Distinction
Hsync and Vsync of each mode is shown in Table 3.

When the detected frequency if the sync signal has changed, the total number of

lines should be counted even through it is range identified frequency in the same
mode.

3.7.2.2Out of range

This out of range mode is assumed when the frequency out of the horizontal /
vertical signal is as specified below.

Vertical frequency : 56 ~ 76 Hz.
Horizontal frequency : 30 ~ 63KHz.

3.7.2.3Power save mode

The power save mode is assumed when the horizontal / vertical signals are as
specified below.

If there is no horizontal sync signal input.
If there is no vertical sync signal input.

If the horizontal sync signal is outside the measuring range of I307 gm2621.
If the vertical sync signal is outside the measuring range of I307 gm2621.

●

●

●

●

●

●

●

●

●

Page 11

R15AAC/AAU (vs15)

Polarity Mode

Resolution H-Freq

(KHz)

Band Width

(MHz)

H V
1 640x480 (59.94Hz) 31.469 25.175 - ­2 640x480 (72Hz) 37.861 31.5 - ­3 640x480 (75Hz) 37.5 31.5 - ­4 720x400 (70Hz) 31.469 28.322 - +
5 800x600 (60Hz) 37.879 40 + +
6 800x600 (72Hz) 48.077 50 + +
7 800x600 (75Hz) 46.875 49.5 + +
8 832x624 (74.55Hz) 49.722 57.28 - ­9 1024x768 (60Hz) 48.363 65 - -

10 1024x768 (75Hz) 60.023 78.75 + +
11 1152x870 (75Hz) 68.68 100 +/- +/­12 1152x900 (76Hz) 71.71 105.6 - ­13 1280x960 (60Hz) 60 108 +/- +/­14 1280x1024 (60Hz) 63.981 108 + +
15 1280x1024 (75Hz) 79.976 135 + +

Table 2 video mode

Table 3 the Hsync, Vsync distinction

Indication
resolution

Distinction Hsync Distinction Vsync The fixed

mode

720 x 400

30.5KHz≦fH≦32.5KHz 69Hz≦fV≦71Hz

4

640 x 480

30.5KHz≦fH≦32.5KHz 59Hz≦fV≦61Hz

1

36.9KHz≦fH≦38.9KHz 71.8Hz≦fV≦73.8Hz

2

36.5KHz≦fH≦38.5KHz 74Hz≦fV≦76Hz

3

800 x 600

36.9KHz≦fH≦38.9KHz 59.3Hz≦fV≦61.3Hz

5

47.1KHz≦fH≦49.1KHz 71.2Hz≦fV≦73.2Hz

6

45.9KHz≦fH≦47.9KHz 74Hz≦fV≦76Hz

7

832 x 624

48.7KHz≦fH≦50.7KHz 73.5Hz≦fV≦75.5Hz

8

1024 x 768

47.4KHz≦fH≦49.4KHz 59Hz≦fV≦61Hz

9

59KHz≦fH≦61KHz 74Hz≦fV≦76Hz

10

1152 x 870

67.7KHz≦fH≦69.7KHz 74Hz≦fV≦76Hz

11

1152 x 900

70.7KHz≦fH≦72.7KHz 75Hz≦fV≦77Hz

12

1280 x 960

59KHz≦fH≦61KHz 59Hz≦fV≦61Hz

13

1280 x 1024

62.9KHz≦fH≦64.9KHz 59Hz≦fV≦61Hz

14

1280 x 1024

79KHz≦fH≦81KHz 74Hz≦fV≦76Hz

15

Page 12

R15AAC/AAU (vs15)

3.7.3List of I/O Pin Assignments of the I311

Pin No.

Port Signal Name Initial

Setting

Function

51 GPIO0 LED_B L LED green enable
56 GPIO1 LED_A L LED amber enable
50 GPO4

BKLT_ADJ

- Backlight brightness control
57 GPO2 MUTE L Mute Audio
58 GPO3 AUDIO_PW L ON/OFF Audio power

115 LBADC_IN1 VGA_DETn H VGA cable connected
127 PPWR PANELVCC_EN L Panel power enable

49 PBIAS BKLT_EN L Back light power enable

Page 13

R15AAC/AAU (vs15)

3)Trouble shooting

1.For Power Board

Check output voltage +5V, +12V, +21.5V are right or not

NG OK It is not power board problem

Check power switch is turn on or not

OK NG Turn switch on

Check power cord (P801), signal cable (P302), P802, P101, P102, P103,

P104 is connected right or not

OK

NG

Check C805 is about DC140V-330V or not

OK

NG

Check C807 is over 11V or not

OK

NG

Connect it right

Check F801, D801, P801 and repair them

Check pin 6 of I801 have same pulse or not

OK

NG

Check pin 1 of T802 have same pulse or not

OK

NG

Check peripheral component of I801 and repair them

Check L805, D804, I801 and repair them

Check peak voltage of R811 triangle pulse is up to 1 volt or not

OK

NG

Check D809, D810, D811, C818. C829, C813, C824, C822, T802 have

same short circuit or the output +5V, +12V, +21.5V is over load

OK

NG

Check feedback circuit around I802, I803 and the other components and

repair them

Repair them

Check D804, L805 and repair them

Check Q803, R813, R814, D806, R811, R815 and repair them