Acer H15AAX User manual

15-inchLCD Monitor
H15AAX
Service Manual

Service ManualVersionsand Revision
Copyright
Copyright2002LiteOnTechnologyCorp.
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TechnologyCorp.
H15AAX(AL502)ServiceManual.
Printed in Taiwan.
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TechnologyCorp.
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No. Version Release Date Revision
1. 1.0 Jan. 31, 2002 Original release

CircuitDescription
H15AAX (AL502)

CircuitDescription
H15AAX (AL502)
Page1
1. Audio circuit (Circuit diagramsMain PWB)
1.1Audioinput
Theaudiosignalinputreceivedfromtheaudioinputterminal(JK011)isappliedtotheamplifierI001 of4(L-
CH)and 9(R-CH)through thelow-pass filterconsisting ofR040,R041,R042,R043,C040 and C041.
Inthisamplifier,controlsofVolumeandmuteareconducted.Theaudiosignalcontrolledatthepin6determines
theattenuationofoutputoftheamplifiers.Sincethen,thesignalisoutputtothejackP003.
1.2Audiooutput
TheaudiosignalisoutputfromP002 outputterminaloftheAudioblocktotheinternalspeakersystem.
2. Powersupply (Circuit daigramsMAINPWB)
2.1LinefilterconsistsofC801,T801,C802,C803,C804.Iteliminateshighfrequencyinterference tomeetEMI’s
requirement.
2.2Rec &Filter:
BridgediodeD801 convertsACsource intopulsedDC.ThispulsedDCissmoothedand filteredby C805.
R802 isanNTC(negativethermalcoefficient)resistor,usedtoreduce inrushcurrenttobewithinsaferange.
2.3Powertransformer:
T802 convertsenergy forsquarewavefrompowersource C805 tosecondarysidetogenerate+12Vand +5V.
2.4Output:
ThesquarewavefromT802 isrectifiedby D809,D810,thenfilteredby C817,C822 togenerate+12Vand
+5Vrespectively.
2.4.1A5VpowersupplyforLCDmodule,CPUand logicisgeneratedfromthepowersource.
2.4.2I308 :3-terminalregulator
A3.3VpowersupplyforI306 analog isgeneratedfromthe5Vsource.
2.4.3I308 :3-terminalregulator
A3.3VpowersupplyforI306 digitalisgeneratedfromthe5Vsource.
Q302,Q303 ON/OFF controlforLCDModule
ON/OFF controlisperformedforpowerON/OFF and alsoforthepowersaving sequence.
2.5Driver:
Q803 driveT802 fromPWMcontrolofI801 forpowerconverted.
2.6FB:
NegativefeedbackCKTconsistsofphotocouplerI802and adjustableregulatorI803.Itcanmaintainoutput
voltages+5Vand +12Vatastablelevel.
2.7PWM:
2.7.1Start:Whenpoweristurnedon,Q801 conductsduetobiasfromC805 andR805,R803.C807 ischargeda16
volt and astarting currentabout0.3mAtopin7ofI801.I801 startstooscillateand outputsapulsetrain
through pin6todriveQ803.
2.7.2OPP :WhenQ803turnson,C805 suppliesalinearlyincreasing trianglecurrentthrough theprimaryinduc
tance ofT802 tothedriverQ803,once thepeakvalueofthiscurrentmultipliedbyR811 exceeds1volt,pulse
trainwill beshutdownimmediatelytoprotectQ803,T802frombeing burnedout.
2.7.3Regulation :If outputvoltage+5Vgoesup,theRterminalofI803 getsmorebias,accordinglyphototransis
torand photodiodeflowsmorecurrent.Thevoltageofpin2goesup too,making thepulsewidthofpin6to
becomenarrower.Sotheoutputvoltage+5Vwill bepulleddowntoastablevalue.

CircuitDescription
H1 5A AX (AL502)
Page2
2.7.4OVP :If +5Vgoesup too much,theinducedvoltageon pin4ofT802 becomeslargealso.Supposethatit is
over18 volts,ZD801 conducts,pin3ofI801 ispulledup over1volt.Thepulsetrainatpin6goesdownto
zero,shutting Q80 3 off immediately.
2.7.5SCP:If outputterminalisshorttoground,phototransistordoesnotconduct,hence Q806 doesnotconduct
either.Thenoscillation ofI801 isstop,shutting Q803 off immediately.
3.On-screencircuit (Circuit diagramsMainPWB)
I3 00 Embededfunctio n.
On-screenmenu screenisestablishedand theresultantdataareoutputfromI300 (Circuit diagramMAINPWB).
4.Videoinputcircuit (Circuit diagramMAINPWB)
TheAC-coupledvideosignalisusedtoclamptheblacklevelat0V).
5.Definition converterLSIperipheralcircuit (Circuit diagramMAINPWB)
I301 MRTV2gmZAN1isthedefinitio n A/DconverterLSI.
Theanalog R,G,Bsignalinputenteredfromthevideoinputcircuit isconvertedintothedigitaldataofvideo
sig nalthro ugh theincorporatedA/Dconverter.Basedon thisconversion,thisdevice per formsinterp olat ion
during pixelextension.Thesource vol tageforthisdevice is3.3Van d thesystemclockfrequencyis12MHz.
Thewithstand voltagelevelfortheinputsignalvoltageis3.3Vand 5V.
6.Systemreset,LEDcontrolcircuit (Circuit diagramMAINPWB)
6.1Systemreset
Systemresetisperformedby detecting therising and falling ofthe5Vsource voltageatI302.
6.2LE Dco ntrolcircuit
Green/amberislit withthecontrolsignaloftheLEDGREENand LEDAMBERsignalpin43,4 2 fromI303
(Circuit diagramMAINPWB).
7.E2PROMforPnP(Circuit diagramMAINPWB)
H15AAU / H15AAR Power Board Block Diagram
Line Filter Rec.
&
Filter
Power
Transformer
Output Rec. & Filter
PWM Driver
FB

Circ uitDescription
H15AAX (AL502)
Page3
8.E2PROM(Circuit diagramMAINPWB)
DatatransferbetweenI30 4 and CPU(Circuit diagramMAINPWBpage4/7(I303)iseffectedthro ugh theIIC
busSCL(pin9)and SDA (pin8)ofI300 orSCL(pin42)and SDA pin39 ofI301.Thedatatobetransferredto
eachdevice arestoredinI304.
l I300 controldata.
l OSDrelatedsetting data.
l Othercontroldataforservice menu.
9.CPUcircuit (Circuit diagramMAINPWB)
I3 03 (MTV312M64)(SM89516C2 5)or(W78E62BP-40 )funct ion sastheCPU.
Thesou rce voltageforthedevice is5.0Vand thesystemclockfrequencyis12MHz.
9.1Detectio n ofPOWERswitchstatus
TheCPUidenti fiestheON statusofthetwopowersupplies.Theidentification ismadewhenthepowersupply
isturnedoff.Forexample,ifthepowersupplyisturnedoff withthePOWERswitch,thePOWERswitchmustbe
turnedon whenactivating thepowersupplyagain.If thepowersupplyisturnedoff by pullin g outthepower
cord,thenthispowersupplycanbeturnedon by connecti ng thepo wercord,wi thoutpressin g thePOWER
swit ch.
9.2Displaymod eidentificat ion
9.2.1Fun ction s
(1)Displaymodeident ificat ion
l Thedisplaymodeofinputsignalisidentifiedbasedon Table1,and according tothefrequencyand polarity
(HPOL,VPOL)ofhorizontalorverticalsyncsignal,presence ofthehorizontalorverticalsyncsignal,and the
discriminati on sig nal(HSYN C_DETECT,VSYN C_DETECT).
l Whenthemodehasbeenidentifiedthrough themeasurementofhorizontaland verticalfrequencies,thetotal
numberoflinesisdeterminedwithaformulaof“Horizontalf requency/Vertic alfrequency=Totalnumber
oflines.“Finalident ific ation canbemadeb y examining thecoincidence oftheob tainedfig urewiththe
numberoflinesforthemodeident ifiedfromthefrequ ency.
l Whenthedetectedfrequencyifthesyncsignalhaschanged,thetotalnumberoflinesshouldbecountedeven
through i t isrgeidentifiedfrequencyinthesamemode.Then,it isnecessarytoexaminewhetherthepreset
valuefortheverti caldisplayposition ofItem4-3hasexceededthetotalnu mberofli nes.If exceeded,a
maximumvalueshouldbesetup,whichdoesnotexceedtheverticaldisplayposition ofItem4-3.
(2)Out-of- ran ge
Thisout-of-rangemodeisas sumedwhenthefrequencyofthehorizontal/verticalsignalisasspecifiedbelow.
l Verticalfrequency:Below50Hzorabove85Hz
l Horizontalfr equency:Below24 KHzorabove75 KHz
(3)Powersavemode
Thepowersavemodeisassumedwhenthehorizo ntal/verticalsig nalsareasspecifiedbelow.
l If thereisno horizontalsyncsignalinput.
l If thereisno verticalsyncsignalinput.
l If thehorizontalsyncsignalisoutsidethemeasuring rangeofI300.
l If theverticalsyncsignalisoutsidethemeasuring rangeofI300.

Circ uitDescription
H1 5A AX (AL502)
Page4
Table1
Attention:
1.Whenresolutionbeyond1024 x768isinputted,resolutionisloweredwithDownscaling to1024 x768,and
indicated,and OSDshouldindicateOUTofRange.
9.3UserControl
9.3.1RelatedportsofI303
Port
Pin No.
I/O
Signal name
Function Remarks
P1.5 7IPOWER Power switch input Power ON , OFF
control
P1.1 3IDOWN switch input ( ) key
P1.0 2IUP switch input ( ) key
P1.3 5I - - switch input ( - ) key
P1.2 4I++ switch input ( + ) key
Polarity
Mode
No Resolution
H-freq
(KHz)
Band Width
(MHz) H V
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 - -
14. 157 VESA 1024 x 768 70Hz
56.48
75 - -
15. 141 VESA 1024 x 768 75Hz
60.02
78.75 + +

CircuitDescription
H15AAX (AL502)
Page5
9.3.2Fun ction s
Controliseffectedforthepush-switchestobeusedwhentheuserchangestheparameters,inordertomodifythe
respec tivesettin g values.Whethertheswitchhasbeenpressedisidentifiedwiththeswitchinputlevelthatis
turned“L”.
Eachswitchinputportispulledup atoutsideofASIC.
EachparameterisstoredintheEEPROM,thecontentsofwhichareupdatedasreq uired.
9.4Controlofdefinition converterLSII300.
9.4.1Portsrelatedtocontrol
Pin No. I/O Signal name Function
159 IIRQ interrupt signal
5I/O SCL serial clock
6I/O SDA serial data
9.4.2Fun ction s
Majorfunction ofI300 areasfollows:
(1)Ex pansion ofthedisplayscreen.
(2)Timing controlforvarioussignaltypes.
(3)Power -supplysequence (LCDpanel).
9.5I2Cbuscontrol
9.5.1RelatedportsofI303
Port Pin No. I/O Signal name Function
P1.7 14 OSCL IIC bus clock
P1.6 13 I/O SDA IIC bus data
9.5.2I2C-control ledfun ctio ns
Thefollowing fu nctionalcontrolsareeffectedby I2C.
(1)ControlofEEPROMI30 4 forparametersetting.

Circ uitDescription
H1 5A AX (AL502)
Page6
9.6PowerON seq uenc e
WhenthePOWERswitchispressed,thePOWEROFF signalisturned“H”.Whenthis“H”potentialisdetected,
theCPUbeginstoestablishtherespe ctivepowersuppliesaccording tothesequence shownbelow.
POWER
PPWR
D-SHCLK
INV_EN
LED
DATA

Circ uitDescription
H15AAX (AL502)
Page7
9.7PowerOFF sequence
WhenthePOWERswitchispressedwhilethepowersupplyisON,thePOWERONsignalisturned“H”.When
tshownbelow.his“H”potentialisdetected,theCPUbeginstoturnoff therespectivepowersuppliesaccording
tothesequence
POWER
PPWR
D-SHCLK
INV_EN
LED
DATA

CircuitDescription
H15AAX (AL502)
Page8
10. Inverter
Thisunit operateson anoutputvoltageof15Vfrompowersource.
10.1Regulator:Q101 geta+5VDCforI102 powersupply.
10.2UVP:Q106turnsoff whentheVinisunder14V.Thenpin3ofI102ispulledlowandinverteroff immediately.
Thatistheundervoltageprotection.
10.3ControlIC:I102 (OZ960S)
10.3.1Enable:Whenpin3ofI102 isover1.5V,I102 works.If it isunder1.5V,I102 turnsoff.
10.3.2OSC:WhenI102enabled,R108/C115 (pin17/pin18 ofI102)determinetheoperating frequency.
10.3.3SST:C104 (pin4ofI102)providessoftstartfunction.
10.3.4Ignition:R109 (pin8ofI102)provideshigheroperating frequencyformorestrikingvoltageuntil regulation
offeedbackoflampcurrent.C103 (pin1ofI102)determinethestriking time.
10.3.5Dimming control:ThedividedvoltageofR106/R105/R104controlthedutypulseofburst-modetodriveQ105
and performawidedimming controlfortheCCFL.Theburst-modefrequencyisdeterminedby C116.
10.3.6Regulation:Pin9/pin10 ofI102 provideregulationoftheCCFLcurrentfromfeedback.Thenon-inverting
reference (pin10 ofI102)isat1.25Vnominal.
10.3.7Protection:Open-lampprotection intheignitionperiod isprovidedthroughbothpin1 and pin2ofI102.
RemovaloftheCCFLduring normaloperation will triggerQ104 toturnson and shutsoff theinverter.This
islatchfunction.
10.3.8Outputdrivers:Theconfiguration preventsany shoot-through issueassociatedwithbridge-typepower
conversion applications.Adjusting theoverlapconduction betweenI101 P-MOSFET and I103 N-MOSFET,
I101 N-MOSFET and I103 P-MOSFET,theCCFLcurrentregulation isachieved.
10.4Full-bridgeswit ching/Transformer:I101/I103/C123/C125/T101/T102 composefull-bridgeswitching to
convertDCintoACfordrivertheCCFL.
10.5Detection:C124/C119/CR102detecttheoutputvoltageandensurearatedvoltagebypin2ofI102.Q102/Q103
ensurenotaopen-lamp.
10.6Feedback:CR101/R120/R121/D108sensethelampcurrentfornegativefeedbackand regulation.Thedivided
voltageon R121 will beat1.25V.
InverterBoardBlockDiagram
VCC
Regulator
U.V.P. Enable
OSC
SST
Dimming
control
Output driver
Protection
Ignition
Regulation
Control IC : OZ960
ON / OFF
Full-bridge switching Transformer Lamp
Feed back
Detection
Brightness
control
VDD

Index
H15AAX (AL502)
Page18
1.Nodisplayofscreen(Screenisblack,colorofLEDisamber)------------------------------------------------------------1
2.Nothing displayson screen(Screenisblack,colorofLEDisgreen) ----------------------------------------------------2
3.Checkingthebacklightunit --------------------------------------------------------------------------------------------------------5
4.Abnormalscreen-----------------------------------------------------------------------------------------------------------------------6
5.NoOSDdisplay------------------------------------------------------------------------------------------------------------------------7
6.Abnormalplug andplayoperation ------------------------------------------------------------------------------------------------8
6.1AbnormalDDC2------------------------------------------------------------------------------------------------------------------8
7.Checking theinterfacecircuit ofsyncsignal-----------------------------------------------------------------------------------9
7.1Checkingthecontrolcircuit ofhorizontalsyncpulse-------------------------------------------------------------------9
7.2Checkingthecontrolcircuit ofverticalsyncpulse----------------------------------------------------------------------9
8.Checking theresolution changeICmovement------------------------------------------------------------------------------- 10
9.Nopoweron--------------------------------------------------------------------------------------------------------------------------- 11
9.1Nopoweron (I)------------------------------------------------------------------------------------------------------------------ 11
9.2Nopoweron (II) ---------------------------------------------------------------------------------------------------------------- 12
10.Checking theDC/DCconvertercircuit----------------------------------------------------------------------------------------- 13
11.CheckingtheoperationofCPU-------------------------------------------------------------------------------------------------- 14
12.Checkingtheaudiocircuit --------------------------------------------------------------------------------------------------------- 15
13.Checking inverterboardcircuit -------------------------------------------------------------------------------------------------- 16
TableofContents

TroubleShootingPage1
H15AAX (AL502)
1.Nodisplayofscreen (Screen isblack,colorofLEDisamber)
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.

Page2 TroubleShooting
H15AAX (AL502)
2.Nothing displays on screen (Screen isblack,colorofLEDisgreen)
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.
OK NG
Proceed "Abnormal screen" section.
Next Page

TroubleShootingPage3
H15AAX (AL502)
Continue
Check if the voltage on I308 pin3 that
is high level DC at 5V.
Check the 3.3 V power are supplied on I308 pin 2.
OK
NG
OK NG
Failure point
I308 Failure
Is a dot clock being outputted under the
condition that a LCD module is connected to
P303 pin 44?
OK NG
Failure point
1) I300 failure
2) Printed wire broke between I302 and P303 pin 44.
Check the H-sync pulse of negative polarity is
output on P303 pin 38 at TTL level.
OK NG
Failure point
1) I300 failure
2) Printed wire broke between I300 and P303 pin 38.
Check the V-sync of negative polarity are
output on P303 pin 40.
OK NG
Next Page
Failure point
1) I300 failure
2) Printed wire broke between I300 and P303 pin 40.
Failure point
1) Printed wire broke between P301 and I308

Page4 TroubleShooting
H15AAX (AL502)
Continue
Check the data enable of positive polarity
are output on P303 pin 42.
OK NG
Failure point
1) I300 failure.
2) Printed wire broke between I300 and P303 pin 42.
Check the data signal output on P306 and
P303 R, G, B data pin.
OK NG
Failure point
1) I306 failure.
2) Printed wire broke between I300 and P303 , P304
data line
Failure point
1) The cable broke between P303 , P304
and LCD module.
2) LCD module failure.

TroubleShootingPage5
H15AAX (AL502)
3.Checking the back lightunit
Is +15V supplied to P803
pin 3, 4 to inverter PWB?
OK
NG Failure point
Inverter cable disconnection.
Check the INV_EN signal of the rectangle input I307 pin 5 at TTL high level
OK
NG Is a "H" level being output in the TTL level from I300 pin 143
Or, is INV_EN signal of the rectangle being output?
NG
Failure point
Printed wire broke between
I300 pin 143 and I307 pin 5
Check the PWM signal of the input from I303 pin 7 is a BRI signal
OK
NG
Failure point
1) Printed wire broke between
I303 pin 17 and I307 pin 3
2) I307 failure.
Failure point
1) Inverter cable disconnection.
2) Inverter of LCD module failure.

Page6 TroubleShooting
H15AAX (AL502)
OK NG
Failure point
1) No R, G and B video signal output from host computer. Check
computer
2) Video signal cable disconnection.
OK NG
Check the R, G, B video signal from computer input on
D-Sub R, G, B connector.
Check the R, G, B input signals on I301 pin 12, 20, 28,
respectively that their level is 0.7Vp-p maximum.
Is the pulse of the TTL level being output to P303, P304
from the data line of I300?
Failure point
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 I301 pin 12.
2) R341 short.
3) C321 open.
4) R362 open.
OK NG Failure point
1) Printed wire broke between I300 data line and P303, P304
2) I317 failure.
Check the negative horizontal sync pulse output to P304
pin 38 from I300 pin 80 at TTL level.
OK NG
Failure point
1) Printed wire broke between I300 pin 80 and P304 pin 38.
2) R351 open
Check the negative vertical sync pulse output to P304 pin
40 from I300 pin 75 at TTL level.
OK NG
Check the positive DE pulse output to P304 pin 42 from
I300 pin 74 at TTL level.
OK NG
Check the SHFCLK OUTPUT to P304 pin 44 from I300
pin 44 at TTL level.
OK NG
Process "Checking the resolution change IC movement"
section.
Failure point
1) Printed wire broke between I306 pin 44 and P307 pin 44.
2) FB314 open
3) FB315 open
4) C380 short
5) C381 short
Failure point
1) Printed wire broke between I300 pin 75 and P304 pin 40.
2) R352 open
3) C416 short
Failure point
1) Printed wire broke between I300 pin 74 and P304 pin 42.
2) R355 open
3) C382 short
4.Abnormalscreen

TroubleShootingPage7
H15AAX (AL502)
5.NOOSDdisplay
OK
NG
Check the input of pulse from I300 pin 5, 6.
Proceed "Checking the resolution change IC movement" section.
Failure point
1) Printed wire broke between I306 pin 5 and I303 pin 9.
2) Printed wire broke between I306 pin 6 and I303 pin 8.

Page8 TroubleShooting
H15AAX (AL502)
6.Abnormalplug and playoperation
6.1AbnormalDDC2
Confirm the input of serial data on I305 pin 6 synchronize SCLK at TTL level.
OK
NG
Failure point
I305 failure.
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 I305 pin 6 and P302 pin 15 may have failed.
4) R337 open.
5) Cable failure.