Page 1
Service Manual
15-inch LCD Monitor
GC150AT/ATA
Page 2
Service Manual Versions and Revision
No. Version Release Date Revision
1. 1.0 July 19, 2001 Original release
Copyright
Copyright 2001 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.
GC150AT/ATA 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.
Page 3
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 ---------------------------------------------------------------------------------------------------------- 2
4. Video input circuit -------------------------------------------------------------------------------------------------------- 2
5. Definition converter LSI peripheral circuit ---------------------------------------------------------------------------- 2
6. System reset, LED control circuit --------------------------------------------------------------------------------------- 2
7. E2PROM for PNP --------------------------------------------------------------------------------------------------------- 2
8. E2PROM -------------------------------------------------------------------------------------------------------------------- 3
9. CPU circuit ----------------------------------------------------------------------------------------------------------------- 3
9.1 Dection of POWER switch status ---------------------------------------------------------------------------------- 3
9.2 Display mode identification ----------------------------------------------------------------------------------------- 3
9.3 User control ----------------------------------------------------------------------------------------------------------- 4
9.4 Control of identification converter LSI (IC306) ------------------------------------------------------------------ 5
9.5 I2C bus control -------------------------------------------------------------------------------------------------------- 5
9.6 Power ON sequence -------------------------------------------------------------------------------------------------- 6
9.7 Power OFF sequence ------------------------------------------------------------------------------------------------- 7
10. Inverter ---------------------------------------------------------------------------------------------------------------------- 8
Circuit Description
Page 4
GC150AT/ATA
1. Audio circuit (Circuit diagrams Main PWB)
1.1 Audio input
The audio signal input received from the audio input terminal (JK011) is applied to the amplifier I001 of 4 (L-
CH) and 9 (R-CH) through the low-pass filter consisting of R040, R041, R042, R043, C040 and C041.
In this amplifier, controls of Volume and mute are conducted. The audio signal controlled at the pin 6 determines
the attenuation of output of the amplifiers. Since then, the signal is output to the jack P003.
1.2 Audio output
The audio signal is output from the jack output terminal (P003) of the Audio board to the internal speaker system.
2. Power supply (Circuit daigrams MAIN PWB)
2.1 Line filter consists of C801, T801, C802, C803, C804. It eliminates high frequency interference to meet EMIs
requirement.
2.2 Rec & 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.
2.3 Power transformer :
T802 converts energy for square wave from power source C805 to secondary side to generate +12V and +5V.
2.4 Output :
The square wave from T802 is rectified by D809, D810, then filtered by C817, C822 to generate +12V and
+5V respectively.
2.4.1 A 5V power supply for LCD module, CPU and logic is generated from the power source.
2.4.2 I310 : 3-terminal regulator
A 3.3V power supply for I306 analog is generated from the 5V source.
2.4.3 I310 : 3-terminal regulator
A 3.3V power supply for I306 digital is generated from the 5V source.
Q303, Q304 ON/OFF control for LCD Module
ON/OFF control is performed for power ON/OFF and also for the power saving sequence.
2.5 Driver :
Q803 drive T802 from PWM control of I801 for power converted.
2.6 FB :
Negative feedback CKT consists of photo coupler I802 and adjustable regulator I803. It can maintain output
voltages +5V and +12V at a stable level.
2.7 PWM :
2.7.1 Start : When power is turned on, Q801 conducts due to bias from C805 and R805,R803. C807 is charged a 16
volt and a starting current about 0.3mA to pin 7 of I801. I801 starts to oscillate and outputs a pulse train
through pin 6 to drive Q803.
2.7.2 OPP : 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 shut down immediately to protect Q803, T802 from being burned out.
2.7.3 Regulation : If output voltage +5V goes up, the R terminal of I803 gets more bias, accordingly photo transis
tor 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 +5V will be pulled down to a stable value.
Page 1Circuit Description
Page 5
GC150AT/ATA
2.7.4 OVP : If +5V goes up too much, the induced voltage on pin 4 of T802 becomes large also. Suppose that it is
over 18 volts, ZD801 conducts, pin 3 of I801 is pulled up over 1 volt. The pulse train at pin 6 goes down to
zero, shutting Q803 off immediately.
2.7.5 SCP : If output terminal is short to ground, photo transistor does not conduct, hence Q806 does not conduct
either. Then oscillation of I801 is stop, shutting Q803 off immediately.
GC150AT/ATA Power Board Block Diagram
Line Filter
Rec.
&
Filter
PWM Driver
Power
Transformer
FB
Output Rec. & Filter
3. On-screen circuit (Circuit diagrams Main PWB)
I306 (gmZAN1) Embeded function.
On-screen menu screen is established and the resultant data are output from I306 (Circuit diagram MAIN PWB
, gmZAN1).
4. Video input circuit (Circuit diagram MAIN PWB)
The AC-coupled video signal is used to clamp the black level at 0V).
5. Definition converter LSI peripheral circuit (Circuit diagram MAIN PWB)
I306 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 20MHz.
The withstand voltage level for the input signal voltage is 3.3V and 5V.
6. System reset, LED control circuit (Circuit diagram MAIN PWB)
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 32, 33 from I302
(Circuit diagram MAIN PWB).
7. E2PROM for PnP (Circuit diagram MAIN PWB)
Page 2 Circuit Description
Page 6
GC150AT/ATA
8. E2PROM (Circuit diagram MAIN PWB)
Data transfer between I304 (L51DC) and CPU (Circuit diagram MAIN PWB page 2/5 (I302) is effected through
the IIC bus SCL (pin 14) and SDA (pin 13) of I302. The data to be transferred to each device are stored in I304.
l I306 control data.
l OSD related setting data.
l Other control data for service menu.
9. CPU circuit (Circuit diagram MAIN PWB)
I302 (MTV312M64) 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 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.
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) Out-of -range
This out-of-range mode is assumed when the frequency of the horizontal / vertical signal is as specified below.
l Vertical frequency : Below 50Hz or above 85Hz
l Horizontal frequency : Below 24 KHz or above 75 KHz
(3) 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.
Page 3Circuit Description
Page 7
Table 1
q
(
)
GC150AT/ATA
Band Width
KHz
1. 247 VGA 720 x 350 70Hz 31.47 28.322 + -
2. 102 VGA 720 x 400 70Hz 31.47 28.322 - +
3. 103 VGA 640 x 480 60Hz 31.47 25.175 - -
4. 182 MAC 640 x 480 66Hz 35 32.24 - -
5. 173 VESA 640 X 480 72Hz 37.86 31.5 - -
6. 109 VESA 640 X 480 75Hz 37.5 31.5 - -
7. 104 VESA 800 x 600 56Hz 35.16 36 + +
8. 116 VESA 800 x 600 60Hz 37.88 40 + +
9. 110 VESA 800 x 600 75Hz 46.88 49.5 + +
10. 117 VESA 800 x 600 72Hz 48.08 50 + +
11. 108 MAC 832 x 624 75Hz 49.72 57.283 - -
12. 118 VESA 1024 x 768 60Hz 48.36 65 - -
13. 217 SUN 1024 x 768 65Hz 52.45 70.49 - -
(MHz)
PolarityMode No Resolution H-fre
HV
14. 157 VESA 1024 x 768 70Hz 56.48 75 - -
15. 141 VESA 1024 x 768 75Hz 60.02 78.75 + +
Attention :
1. 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 I306
Port Pin No. I/O Signal name Function Remarks
MFB0 113 I POWER Power switch input Power ON , OFF
control
MFB10 124 I DOWN switch input ( ) key
MFB4 109 I UP switch input ( ) key
MFB11 123 I - - switch input ( - ) key
MFB3 110 I + + switch input ( + ) key
Page 4 Circuit Description
Page 8
GC150AT/ATA
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 I306
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 I306 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 I302
Port Pin No. I/O Signal name Function
P3.5 14 O IICCLK IIC bus clock
P3.4 13 I/O IICDATA IIC bus data
9.5.2 I2C-controlled functions
The following functional controls are effected by I2C.
(1) Control of EEPROM I304 for parameter setting.
Page 5Circuit Description
Page 9
GC150AT/ATA
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
INV_EN
LED
DATA
Page 6 Circuit Description
Page 10
GC150AT/ATA
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
tshown below.his H potential is detected, the CPU begins to turn off the respective power supplies according
to the sequence
POW ER
PPWR
DOTCLK
INV_EN
LED
DATA
Page 7Circuit Description
Page 11
GC150AT/ATA
10. Inverter
This unit operates on an output voltage of 15V from power source.
10.1 Regulator: Q101 get a +5VDC for I102 power supply.
10.2 UVP: Q106 turns off when the Vin is under 14V. Then pin 3 of I102 is pulled low and inverter off immediately.
That is the under voltage protection.
10.3 Control IC: I102 (OZ960S)
10.3.1 Enable : When pin 3 of I102 is over 1.5V, I102 works. If it is under 1.5V, I102 turns off.
10.3.2 OSC: When I102 enabled, R108/C115 (pin 17/pin18 of I102) determine the operating frequency.
10.3.3 SST: C104 (pin 4 of I102) provides soft start function.
10.3.4 Ignition: R109 (pin 8 of I102) provides higher operating frequency for more striking voltage until regulation
of feedback of lamp current. C103 (pin 1 of I102) determine the striking time.
10.3.5 Dimming control: The divided voltage of R106/R105/R104 control the duty pulse of burst-mode to drive Q105
and perform a wide dimming control for the CCFL. The burst-mode frequency is determined by C116.
10.3.6 Regulation: Pin 9/pin 10 of I102 provide regulation of the CCFL current from feedback. The non-inverting
reference (pin 10 of I102) is at 1.25V nominal.
10.3.7 Protection: Open-lamp protection in the ignition period is provided through both pin1 and pin 2 of I102.
Removal of the CCFL during normal operation will trigger Q104 to turns on and shuts off the inverter. This
is latch function.
10.3.8 Output drivers: The configuration prevents any shoot-through issue associated with bridge-type power
conversion applications. Adjusting the overlap conduction between I101 P-MOSFET and I103 N-MOSFET,
I101 N-MOSFET and I103 P-MOSFET, the CCFL current regulation is achieved.
10.4 Full-bridge swit ching/Transformer: I101/I103 /C123/C125/T101/T102 compose full-bridge swit ching to
convert DC into AC for driver the CCFL.
10.5 Detection: C124/C119/CR102 detect the output voltage and ensure a rated voltage by pin2 of I102. Q102/Q103
ensure not a open-lamp.
10.6 Feedback: CR101/R120/R121/D108 sense the lamp current for negative feedback and regulation. The divided
voltage on R121 will be at 1.25V.
Inverter Board Block Diagram
VCC
Regulator
VDD
ON / OFF
Brightness
control
Control IC : OZ960
U.V.P. Enable
OSC
SST
Dimming
control
Output driver
Protection
Ignition
Regulation
Full-bridge switching
Transformer
Detection
Feed back
Lamp
Page 8 Circuit Description
Page 12
GC150AT/ATA
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
5. No OSD display ----------------------------------------------------------------------------------------------------------- 7
6. Abnormal plug and play operation ------------------------------------------------------------------------------------- 8
6.1 Abnormal DDC1 ------------------------------------------------------------------------------------------------------ 8
6.2 Abnormal DDC2 ------------------------------------------------------------------------------------------------------ 8
7. Checking the interface circuit of sync signal -------------------------------------------------------------------------- 9
7.1 Checking the control circuit of horizontal sync pulse ----------------------------------------------------------- 9
7.2 Checking the control circuit of vertical sync pulse--------------------------------------------------------------- 9
8. Checking the resolution change IC movement -----------------------------------------------------------------------10
9. No power on -------------------------------------------------------------------------------------------------------------- 11
9.1 No power on (I) ------------------------------------------------------------------------------------------------------11
9.2 No power on (II) -----------------------------------------------------------------------------------------------------12
10. Checking the DC/DC converter circuit -------------------------------------------------------------------------------- 13
11. Checking the operation of CPU ---------------------------------------------------------------------------------------- 14
12. Checking the audio circuit ----------------------------------------------------------------------------------------------15
13. Checking inverter board circuit ----------------------------------------------------------------------------------------16
Trouble Shooting
Page 13
1. No display of screen (Screen is black, color of LED is amber)
Does OSD display when
you push key button.
Yes
Check if the sync signal from Computer
is output and if the video cable is
connected normally.
No
Proceed "No OSD 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.
GC150AT/ATA
Trouble Shooting Page 1
Page 14
2. Nothing displays on screen (Screen is black, color of LED is green)
Is backlight lit?
OK
Does computer output RGB video signals?
NG
Refer "Checking the backlight unit" section
OK
Check OSD menu is displayed on screen
when you push the "PROCEED" key.
NG
1) Change pattern of video signal output on the
host.
2) Reconnect the video cable.
3) Change the video cable.
Check the video cable for failure. Check the host for
output signal with all black only.
OKNGProceed "Abnormal screen" section.
Next Page
GC150AT/ATA
Page 2 Trouble Shooting
Page 15
Continue
Check the 3.3 V power are supplied on I310 pin 2.
Check if the voltage on I310 pin3 that
NG
OK
is high level DC at 5V.
OK
Failure point
I310 Failure
NG
GC150AT/ATA
Failure point
1) Printed wire broke between P301 and I310
Is a dot clock being outputted under the
condition that a LCD module is connected to
Check the H-sync pulse of negative polarity is
output on P307 pin 38 at TTL level.
Check the V-sync of negative polarity are
P307 pin 44?
OK
OK
output on P307 pin 40.
OK
NG
NG
NG
Failure point
1) I306 failure
2) Printed wire broke between I306 and P307 pin 44.
Failure point
1) I306 failure
2) Printed wire broke between I306 and P307 pin 38.
Failure point
1) I306 failure
2) Printed wire broke between I306 and P307 pin 40.
Next Page
Trouble Shooting Page 3
Page 16
Continue
Check the data enable of positive polarity
are output on P307 pin 42.
OK
Check the data signal output on P306 and
P307 R, G, B data pin.
NG
GC150AT/ATA
Failure point
1) I306 failure.
2) Printed wire broke between I306 and P307 pin 42.
Failure point
OK
Failure point
1) The cable broke between P306 , P307
and LCD module.
2) LCD module failure.
NG
1) I306 failure.
2) Printed wire broke between I306 and P307 , P306
data line
Page 4 Trouble Shooting
Page 17
3. Checking the back light unit
Is +15V supplied to P803
pin 3, 4 to inverter PWB?
OKNGFailure point
Inverter cable disconnection.
Check the INV_EN signal of the rectangle input I309 pin 5 at TTL high level
OKNGIs a "H" level being output in the TTL level from I302 pin 2
Or, is INV_EN signal of the rectangle being output?
NG
Failure point
Printed wire broke between
I302 pin 2 and I309 pin 5
Check the PWM signal of the input from I302 pin 1 is a BRI signal
OKNGFailure point
1) Printed wire broke between
I302 pin 1 and I309 pin 3
2) I309 failure.
Failure point
1) Inverter cable disconnection.
2) Inverter of LCD module failure.
GC150AT/ATA
Trouble Shooting Page 5
Page 18
4. Abnormal screen
GC150AT/ATA
Check the R, G, B video signal from computer input on
Check the R, G, B input signals on I306 pin 95, 91, 87,
Is the pulse of the TTL level being output to P306, P307
Check the negative horizontal sync pulse output to P307
D-Sub R, G, B connector.
OK
respectively that their level is 0.7Vp-p maximum.
OK
from the data line of I306?
OK
pin 38 from I306 pin 74 at TTL level.
NG
NG
NG
1) No R, G and B video signal output from host computer. Check
computer
2) Video signal cable disconnection.
In case of the Red signal. (A Green and Blue signal is the same
path, too.)
1) Printed wire broke between D-Sub(R) and I306 pin 95.
2) R346 short.
3) C348 open.
4) R345 open.
1) Printed wire broke between I306 data line and P306, P307
2) I317 failure.
Failure point
Failure point
Failure point
OK
Check the negative vertical sync pulse output to P307 pin
40 from I306 pin 73 at TTL level.
OK
Check the positive DE pulse output to P307 pin 42 from
I306 pin 43 at TTL level.
OK
Check the SHFCLK OUTPUT to P307 pin 44 from I306
pin 44 at TTL level.
OK
Process "Checking the resolution change IC movement"
section.
NG
NG
NG
NG
1) Printed wire broke between I306 pin 74 and P307 pin 38.
2) R350 open
3) C383 short
1) Printed wire broke between I306 pin 73 and P307 pin 40.
2) R351 open
3) C384 short
1) Printed wire broke between I306 pin 43 and P307 pin 42.
2) R352 open
3) C385 short
1) Printed wire broke between I306 pin 44 and P307 pin 44.
2) FB312 open
3) FB311 open
4) C354 short
5) C355 short
Failure point
Failure point
Failure point
Failure point
Page 6 Trouble Shooting
Page 19
5. NO OSD display
Check the input of pulse from I306 pin 98,103, 99, 102, 104, 105.
Failure point
NG
1) Printed wire broke between I306 pin 99 and I302 pin17.
OK
2) Printed wire broke between I306 pin 102 and I302 pin21.
3) Printed wire broke between I306 pin 104 and I302 pin20.
4) Printed wire broke between I306 pin 105 and I302 pin18.
5) Printed wire broke between I306 pin 103 and I302 pin22.
6) Printed wire broke between I306 pin 98 and I302 pin23.
Proceed "Checking the resolution change IC movement" section.
GC150AT/ATA
Trouble Shooting Page 7
Page 20
6. Abnormal plug and play operation
6.1 Abnormal DDC1
Confirm the input of serial clock on I308 pin 7 synchronize VCLK at TTL level.
GC150AT/ATA
1) The host machine isn't communicating in DDC1 mode.
2) The video cable may have failed or may not to have connections for DDC.
3) Between I308 pin 5 and P302 pin 12 may have failed.
4) R338 open.
5) Cable failure.
6.2 Abnormal DDC2
NG
OK
Confirm the input of serial data on I308 pin 6 synchronize SCLK at TTL level.
1) This mode may be in DDC2B
If you change the mode of DDC1, turn off the power switch of the host
and the monitor and power again.
2) I308 failure.
Failure point
Failure point
NG
OK
Failure point
1) The host machine isn't communicating in DDC2 mode.
2) The video cable may have failed or may not to have connections for DDC.
3) Between I308 pin 6 and P302 pin 15 may have failed.
4) R337 open.
5) Cable failure.
Failure point
I308 failure.
Page 8 Trouble Shooting
Page 21
7. Checking the interface circuit of sync signal
7.1 Checking the control circuit of horizontal sync pulse
GC150AT/ATA
Check the horizontal sync signal on I306
Process "Checking the resolution change IC
pin 150 TTL level.
NG
OK
movement" section.
1) Video cable may have failed.
2) Printed wire broke between P302 pin 13
and I306 pin 150
3) FB302, R332 open
7.2 Checking the control circuit of vertical sync pulse
Failure point
Check the vertical sync signal on I306 pin
Process "Checking the resolution change IC
148 TTL level.
NG
OK
movement" section.
Failure point
1) Video cable may have failed.
2) Printed wire broke between P302 pin 14 and I306 pin
148
3) FB301, R328 open
Trouble Shooting Page 9
Page 22
8. Checking the resolution change IC movement
Is there +3.3V supply on I306 pin 77, 79, 84, 96, 92, 88, 8, 129, 136, 139, 137, 143, 11, 21,
58, 108, 149, 12, 33, 40 and 65.
OKNGIs 20MHz clock input to I306 pin 141
at TTL level?
Proceed "Checking the DC/DC converter circuit" section.
OKNGIs 20MHz clock output from X301
at TTL level?
OKNGFailure point
Print wire broke between X301 and
I306 pin 141.
Failure point
X301 failure
Is +5.0V supplied to I306 pin 100 at
High level?
OKNGCheck the output of 5.0V "H" pulse
from I301 pin 6.
OKNGIs 5.0V supplied to I301 pin 7?
Failure point
I306 failure
Failure point
Print wire broke between I301 pin 6
and I306 pin 100.
OKNGFailure point
I301 failure
Failure point
1) FB318 open
2) Power source
GC150AT/ATA
Page 10 Trouble Shooting
Page 23
9. No power on
Check output voltage +5V,
+15V is right or not.
NGOKCheck power switch is turn on
or not.OKNG
Check power cord ( P801), Signal cable
(P302),P802, P803, CN102, CN103
is connected right or not.
It is not power board
problem.
Turn switch on.
OKNGCheck C805 is about DC
140V-330V or not.
Connect it right.
OKNGCheck C807 is over
10V or not.
Check F801, D801, P801
and repair them.
OK
NG
Check pin 6 of I801 have
same pulse or not.
Check R805, R803, I801
and repair them.
OKNGCheck pin 1 of T802 have
same pulse or not.
Check peripheral components
of I801 and repair them.
OKNGCheck peak voltage of R811 triangle
pulse is up to 1 volt or not.
Check Q803, R813, R814, D806
, R812 and repair them.
OKNGCheck D809, D810, C816, C821, T802
have same short circuit, or the output
+5V, +15V is over load.
Check D804, R807 and
repair them.
NGOKCheck feedback circuit around I802,
I803 and the other components
and repair them.
Repair them.
9.1 No power on (I)
GC150AT/ATA
Trouble Shooting Page 11
Page 24
9.2 No power on (II)
GC150AT/ATA
Check the + 5V power is supplied
from power source.
OK
NG
Is LED turned on in amber
momentarily when a power button is
pushed?
NG
OK
Proceed "Checking the operation of
CPU".
Failure point
Power source failure.
Failure point
Power source failure.
Page 12 Trouble Shooting
Page 25
10. Checking the DC/DC converter circuit
GC150AT/ATA
Check the output of 3.3V line voltage
from I310 pin 2.
Is the output FB320 being inputted
NG
OK
Printed wire broke between I310 pin 2 and I306 power supply pin.
OK
to I315 pin 3?
NG
Printed wire broke between I310
Failure point
I310 failure
Failure point
Failure point
pin 3 and output of FB321.
Trouble Shooting Page 13
Page 26
11. Checking the operation of CPU
Is there +5.0V supply on I302 pin 8
OKNGFailure point
Printed wire broke between output of FB319 and I302 power supply pin.
Is 20MHz clock input to I302 pin 11
and 12 at TTL level?
OKNGFailure point
X301 failure.
Check the input of 5V "H" pulse from
I303 pin 4 are same as I302 pin 7.
(14 msec Typ)
OKNGFailure point
1) Printed wire broke between I303 pin 4 and I302 pin 7.
I302 failure.
GC150AT/ATA
Page 14 Trouble Shooting
Page 27
12. Checking the audio circuit
Is a cable with the
host PC connected?
OKNGFailure point
Audio cable disconntction.
Aren't the setups of the
host PC a minimum and off?
OKNGFailure point
The setup of the host PC is changed.
Is correct output waveform
being inputted from JK011
pin 2, 3 of the host PC?
OKNGIs the waveform which is the
same as JK011 being
inputted to I001 pin 4, 9?
Failure point
Audio cable disconntction.
OKNGFailure point
1) Printed wire broke between JK011 pin 2, 3 and I001 pin 4, 9.
2) R040, R041 open.
3) R042, R043 short.
4) C040, C041 open.
Is output wavefrom being
outputted in I001 pin 14, 17?
OKNGIs 15V supplied to I001 pin 15, 16?
OKNGFailure point
1) Speaker cable disconnection
2) Speaker failure
Proceed section 9.1 "No power on".
Is mute/STD-BY low level at pin 11,
pin 12.
OKNGProceed section 11 "Checking
the operation of CPU".
Is Variable DC volume
control at pin 6.
OKNGCheck I002 pin 8 is 5V DC.
Proceed section 11 "Checking
the operation of CPU".
OKNGProceed section 9.1 "No power on".
Failure point
I001 failure.
GC150AT/ATA
Trouble Shooting Page 15
Page 28
13. Checking inverter board circuit
Check Vin pin is around 15.5V.
On/off pin is over 2V.
Brightness pin is between 0V and 3.7V.
OKNGCheck pin 5 of I102 is 5V.
OKNGCheck CN102, CN103 is connected
right.
It is not inverter problem.
Check Q101, D101, D104 and repair
them.
OKNGCheck pin 3 of I102 is over 2V.
Check CCFL and repair them.
OKNGCheck pin 18 of I102 is triangle
pulse.
Check Q106, D110 and repair them.
Check pin 4 of I102 there is soft start
edge up to 4V and pin 11, 12, 19, 20
there is some pulse output.
Check C115, R108, I102 and repair
them.
Check pin 2 of I102 there is up to 2V
from output detection.
Repair I102.
Check full-bridge (I101, I103, D102,
D103, C123, C125) work right.
Check Q102, Q103, CR101, CR103
and repair them.
Repair them.
Check transformer (T101, T102)
work right.
OKNGOKNGNGOKOKNGCheck detection (C124, C118, C126,
CR102 and like those) work right
and repair them.
OKNGRepair them.
GC150AT/ATA
Page 16 Trouble Shooting
Page 29
GC150AT/ATA
1. Recommended Parts List
Note: 1. The components identified by mark are critical for X-ray safety. Replace these with
only the same parts specified.
2. There is only OTP IC at the model beginning (FPR stage or before). When it put in mass
production and there must be Mask coming out. If you have spart parts need, please use BOM
to get the last release part number and related information.
No. Location Part Number Description
1 I301 6444006108 IC M51953AFP 8P SOP
2 I302 6448015578 IC MTV312MV64 44P PLCC
3 I303 6446008108 IC NC7SZ04M5X SOT-23-5
4 I304 6448016118 IC S524L50X51 8P PDIP
5 I305 6446007908 IC NC7SZ08M5X SOT-23-5
6 I306 6444007308 IC gmZAN1 160P PQFP
7 I308 6448007420 IC AT24C21-10PC 8P PDIP
8 I309 6442001978 IC LM358DR 8P SOP
9 I310 6442023326 IC AIC1084-33CM 3P T0263
10 Q301 6442007208 TR NPN SST2222A SOT-23
11 Q303 6427002608 FET-P-CHNL NDS352AP SOT-23
12 Q304 6442007308 TR NPN SST3904 SOT-23
Recommended Spare Parts List Page 1
Page 30
LITE-ON TECHNOLOGY CORP.
5 F, No. 16, Sec. 4, Nanking E. Road, Taipei, Taiwan
Tel: 886-2-25706999 Fax: 886-2-25706888
URL:// www.liteontc.com.tw
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