Acer AL1702 User manual

17-inch LCD Monitor
AL1702
ServiceManual

Service Manual Versions and Revision
Copyright
Copyright 2004LiteOn Technology Corp.
All Rights Reserved
This manual maynot,in wholeorin part,be
copied,photocopied, reproduced, translated, or
converted to anyelectronic or machine readable
formwithout prior written permission of LiteOn
TechnologyCorp.
ACER AL1702 Service Manual.
Printedin Taiwan.
Trademarks
LiteOn is a registered trademark of LiteOn
Technology Corp.
All other trademarks are the property of their
respectiveowners.
No.VersionReleaseDateRevision
1.1.0May12,2004Originalrelease

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AL1702
1) CircuitDescription
1.PowerBoard Operation Therory--------------------------------------------------------------------------------------------3
2.Inverter--------------------------------------------------------------------------------------------------------------------------4
3.Interface-------------------------------------------------------------------------------------------------------------------------5
3.1 Top---------------------------------------------------------------------------------------------------------------------------5
3.2Power------------------------------------------------------------------------------------------------------------------------5
3.3VGA &DDCinterface-----------------------------------------------------------------------------------------------------5
3.4Scaler MST8111A---------------------------------------------------------------------------------------------------------5
3.5 Panel interface--------------------------------------------------------------------------------------------------------------5
3.6 Audio------------------------------------------------------------------------------------------------------------------------7
4.Others---------------------------------------------------------------------------------------------------------------------------7
4.1 Detection of POWER switch status------------------------------------------------------------------------------------7
4.2 Display modeidentification----------------------------------------------------------------------------------------------7
4.3 Power ONsequence------------------------------------------------------------------------------------------------------8
4.4 Power OFF sequence-----------------------------------------------------------------------------------------------------8
4.5ListofI/O PinAssignmentsoftheI307--------------------------------------------------------------------------------9
2)Trouble Shooting
1.Nodisplay of screen(Screenisblack,color of LED isamber)--------------------------------------------------------11
2.Nothing displayson screen(Screen is black, color ofLED is green)------------------------------------------------12
3.Checking the back lightunit-----------------------------------------------------------------------------------------------15
4.Abnormalscreen-------------------------------------------------------------------------------------------------------------16

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AL1702
6.Abnormal plug and playoperation---------------------------------------------------------------------------------------18
7.Checking the interface circuit ofsync signal----------------------------------------------------------------------------19
7.1 Checkingthe control circuit ofhorizontal sync pulse-------------------------------------------------------------19
7.2 Checking the control circuitof vertical sync pulse----------------------------------------------------------------19
8Checking the resolution change IC movement--------------------------------------------------------------------------20
9.Checking theDC/DC converter circuit-----------------------------------------------------------------------------------21
10.Checking theAudio circuit [option]--------------------------------------------------------------------------------------22
11.Checking inverter board circuit--------------------------------------------------------------------------------------------23
12.Power board------------------------------------------------------------------------------------------------------------------24
3)Spare Parts
RecommendedSpare PartsList-------------------------------------------------------------------------------------------------25

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AL1702
1) CircuitDescription
1.PowerBoard Operation
1.1Line filter consists of C801, T801, C802, C803, C804. It eliminates high frequencyinterference to meet EMI s
requirement.
1.2Rec &Filter
Bridge diode D801 convertsAC source into pulsed DC. Thispulsed DC is smoothed and filtered by C805.
R802 isan NTC( negative thermalcoefficient) resistor, used to reduce inrushcurrent to be within saferange.
1.3Powertransformer:
T802 convertsenergyfor square wave frompower sourceC805 to secondaryside to generate+12Vand+22V.
1.4Output :
The squarewave fromT802 is rectifiedbyD809, D811, then filteredbyC822, C817 togenerate +12Vand+22V
respectively.I804 is theregulator for +5V output.
1.5Driver:
Q803 drive T802 fromPWM controlofI801 for power converted.
1.6FB:
Negativefeedback CKTconsists of photo coupler I802 and adjustable regulator I803. It can maintain output
voltages+22V and+12Vatastablelevel.
1.7PWM :
1.7.1Start:When poweristurnedon, Q801 conductsdue tobiasfromC805 andR805,R803. C807 is chargeda
16 voltand a starting current about 0.3mA to pin 7 of I801. I801 startsto oscillateand outputs a pulse
trainthroughpin6to driveQ803.
1.7.2OPP:When Q803 turnson, C805 suppliesalinearly increasing triangle currentthrough the primary
inductanceof T802 to thedriver Q803, oncethepeakvalue of thiscurrent multiplied by R811 exceeds1
volt, pulsetrainwillbe turnoffimmediately to protectQ803, T802 from being burned out.
1.7.3Regulation :Ifoutputvoltage+22V or 12V goesup, theRterminalof I803 getsmorebias,accordingly
photo transistor and photo diode flows more current. The voltage of pin 2 of I801 goes up too, making
the pulse widthofpin6of I801 to become narrower. So the outputvoltage+5V will be pulled down to a
stable value.
1.7.4OVP : If +22Vor 12V goesuptoo much,theinduced voltageon pin 4of T802 becomeslargealso.
Suppose that it isover 18 volts, ZD801 conducts, pin 3 of I801 is pulled up over 1 volt. The pulse train at
pin 6of I801 goes down tozero, shuttingQ803 off immediately.
1.7.5SCP:If output terminal is short to ground, phototransistor does not conduct, hence Q806 does not
conducteither. Then oscillationof I801 is stop, shutting Q803 offimmediately.
Line
Filter
Rec. &
Filter Power
Transformer OutpurRec. &Filter
PWM Driver
FB
Power Board BlockDiagram

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AL1702
2.Inverter Operation
This unit operates on an output voltage of 22Vfrompower source.
2.1VCC:WhenOn/Off pinof P802 ishighlevel input, Q106 turnson and provides +5VDCfor I101 powersupply.
2.2Control IC: I101 (OZ960S)
2.2.1Enable :When pin 3ofI101 is over1.5V,I101 works.Ifitis under1.5V,I101 turns off.
2.2.2OSC:WhenI101 enabled, R108/C115 (pin17/pin18 ofI101) determinethe operating frequency.
2.2.3SST: C104 (pin 4of I101) provides soft start function.
2.2.4Ignition:R109 (pin 8 of I101) provideshigher operatingfrequency for more strikingvoltageuntil regula-
tionof feedbackoflampcurrent.C103 (pin1ofI101) determinethestrikingtime.
2.2.5Dimmingcontrol: Thedividedvoltageof R106/R105/R104 controlthedutypulse ofburst-modeto drive
Q105andperformawidedimmingcontrolfor the CCFL.The burst-modefrequencyis determinedbyC116.
2.2.6Regulation:Pin 9/pin 10 ofI101 provide regulationoftheCCFL currentfromfeedback.The non-inverting
reference(pin 10 ofI101) isat 1.25Vnominal.
2.3Protection:Open-lampprotectionintheignitionperiod is provided throughbothpin1 andpin2of I101 to ensure
a rated voltage is achieved and a required timing is satisfied.
RemovaloftheCCFLduringnormal operation will triggerthe currentamplifier(pin9/pin 10 of I101) outputand
shuts off theinverter. This is latch function.
2.4
2.4.1Output drivers: The configuration prevents anyshoot-through issue associated with bridge-type power
conversionapplications.Adjustingthe overlapconductionbetween I102 P-MOSFET and I103 N-MOSFET,
I101 N-MOSFET andI103 P-MOSFET,the CCFLcurrentregulationis achieved.
2.4.2Full-bridge switching/Transformer:I102/I103 /C123/T101 compose full-bridge switchingto convert DC
into AC for drivertheCCFL.
2.5Detection: C128/C129/C132/D115/D114/C118 detect the output voltage and ensure a rated voltage by pin2 of
I101.
2.6Feedback: D116/D117/R120/D108/R116 sense thelampcurrentfor negativefeedback andregulation.The divided
voltage onR116 will beat 1.25V.
Inverter CircuitBlockDiagram
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

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AL1702
3.Interface Operation
3.1Top (CircuitdiagramsMAIN PWB 2of 8)
Thispage is functionblock.(1) power.(2) VGA&DDC interface.(3) scaler MST8111B. (4) panel interface.(5)
audio (option).
3.2Power(Circuit diagramsMAINPWB 3of8)
3.2.1P301 connector
A5V powersupplyfor LCDmodule,MCU, logic. And a12V powersupply for audiofunction.It is
generated fromthe P301 connector.
3.2.2I301:3-terminal regulator
A 2.5V powersupply for scaler ICI305, it is generatedfrom the5Vsource.
3.2.3I302:3-terminal regulator
A 3.3V powersupply for scaler I305, it is generated from the 5V source.
3.2.4Q303,I312:ON/OFF controlforLCD module power
ON/OFFcontrol(PANELVCC_EN) isperformedfor powerON/OFFand alsofor thepowersaving
sequence.
3.2.5R306 :ON/OFF control for LCD module back lightpower
ON/OFFcontrol (BKLT_EN) is performedfor blacklight powerON/OFFandalsofor thepowersaving
sequence.
3.2.6Q301,Q302 :Adjust back light luminance for LCDmodule
Itisadjusted backlightluminancecontrol (BKLT_ADJ) isperformedfor the back light luminance.
3.3VGA&DDC interface (CircuitdiagramsMAIN PWB 4of8)
The analog video signals input, the AC-coupled video signal video signal is used to clamp the black level at
0V. and H/Vsync to sclaer, and DDC plug & playfunction.
3.3.1P302 connector
Thevideo inputsignals fromthe P302 connector.
3.3.2I304DDCEEPROM
This IC is support DDC2B oftheVESAstandard, also plug and playfor thePChost.
3.4ScalerMST8111B(Circuitdiagrams MAINPWB 5of8)
TheI305 is scaled converter LSI for the LCD monitor.
Theanalog R, G, B signal input entered fromthe video input circuit is converted into thedigital data of video
signal through the incorporated A/Dconverter.Basedon this conversion, this device performs interpolation
during pixel extension.Theseinterpolation digital dataaretransformed to LVDSsignal.TheI305 source
voltageis3.3Vand2.5V,thedeviceclock frequency is14.318 MHz.The devicecontrolsignalisfromMCU
through the 3-wire bus.
The I305 scalerhas supportOSD function.
3.5Panelinterface(Circuit diagrams MAIN PWB 6of 8)
3.5.1P305 connector
The P305 isLVDS bus, outputto LCDmodule.The output voltage is5 voltage.
3.5.2MCU (Circuit diagramsMAINPWB 7of8)
The I307 MCU is system processor. It can programmed scaler, control power save sequence for the
system,inputkeypad function, output LED, control audio function, and ISP/ DDC2Bi function.

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AL1702
3.5.3X302 crystal
TheX302 crystalis11.0592MHz, support theoperated clockto theMCU.
3.5.4Reset circuit
The C396, R379, D316 is support reset signal to theMCU, thenMCU have outputhardware reset signal
(HWRESET) tothe scaler.
3.5.5I308EEPROM
TheI308 is24LC16 EEPROM, the datatransfer betweenI308 andMCUis effected through theIIC bus
SCL(pin14) andSDA(pin13) of MCU. TheOSDrelatedsetting data,I305 control dataand otherservice
data, to be stored in I308.
3.5.6P308 connector
The P308 has support keypadfunction. Control is giveeffectto for the push switch to be used when
the userchangestheparameters, in orderto modify the respective setting values. Whetherthe switch
has been pressed is identifiedwith theswitch input level that is turned “L”.
Each switch input port is pulled up at outside of MCU. Related ports of I307 based on Table1.
Each parameter is stored in the I308 EEPROM, the contents of which are updated as required.
The P308 have LEDGreen andAmber light,theLEDGreen signal pin 36 fromI307 MCU,andtheLED
Ambersignal pin 37 from I307 MCU.
Table 1Relatedports ofI307
Pin No. I/O Signal nameFunction Remarks
Pin 3 IKEY_POWER Soft power switch input Power key
Pin 2 IKEY_MENU Exit/Enter switchinput Enter / withdrawfrom
OSD
Pin 41 IKEY_DOWN switch input Down key
Pin 42 IKEY_MINUS ←switch input - / Mute key
Pin 1 IKEY_PLUS →switch input + / Auto key
3.5.7Audio controlfunction
The I307 MCU output signal controlaudio mute and power, the pin33 is mute signal, thepin32 is
controlled audio power signal.
3.5.8Scaler programmedfunction
The I307 MCUis usedDDRdirect bus,between I305 MST8111B andMCU I307.
3.5.9ISP and DDC2Bifunction
TheDDC2Bi isVESAstandard for thehostPC system, itcanthroughDDC2Bibus controlLCDmonitor.
The I309 will offDDC_CLKandDDC_DATsignal,when LCDmonitor is nopower.
Can useISP function for firmwaremodification.
Thepin29 isbus clock(DDC_CLK), thepin28 isbusdata(DDC_DAT). It is sameof theIIC databus.
3.5.10The powersave sequencefunction
Firstdisable I307 pin31 (BKLT_EN)from Hto LofLCDmodule back lightpower,delaysometime,then
disable I307pin9(PANELVCC_EN)fromHtoLofLCDmodule power,anddisableI307pin32
(AUDIO_EN)fromHto Lofaudiopower,andthrough 3-wirebus programmed I305 MST8111B to
power down mode.

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AL1702
3.6Audio(Circuit diagramsMAINPWB 8of 8) [OPTION]
3.6.1P309 connector
Theaudio signalinputreceivedfrom theaudio input terminal P309 fromthejackinput of thejack
board, P309 isappliedtoamplifier I311ofpin4(L-CH)andpin9(R-CH)through the low-pass filter
consistingofR417, R418,C419 and C420.
3.6.2P310 connector
The audio signal is output to the audio output terminal P310, and to the internal speaker system.
3.6.3I310MOSFET
I310 MOSFET(CEM9435A)is cutaudiopower(12V) for thepowersave sequence.Thesignal
(AUDIO_EN)is ON/OFF I310 MOSFET through the Q311 control.
3.6.4I311amplifier
TheI311TDA7496Lisaudioamplifier,I311operatedpowervoltage is 12V.
I311 pin4 andpin9is audio input port.
I311 pin14 and pin17 is audio output port.
I311 pin 12 is mute input fromI307 MCU.The pin 6is audiovolumefromthe I305 MST8111B.
4Others
4.1Detection of POWER switch status
The MCU identifies the ONstatus of the two power supplies. The identification is made when the
power supplyis 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 supplyagain. If the power supplyis turned off
by pulling outthe power cord,then this power supplycanbeturned on byconnecting the powercord,
without pressing the POWER switch.
4.2Display modeidentification
4.2.1Display modeidentification
The display mode of input signal is identified based on Table 2.
When the mode hasbeen identified through the measurement of horizontal and vertical frequencies,
the totalnumber oflines is determined with aformula of “Horizontalfrequency /Vertical frequency=
Totalnumber ofnumber of lines”.Final identification canbe made byexamining the coincidence of the
obtained figure with the number of lines for the modeidentified fromthe frequency. The Distinction
Hsync and Vsync of each mode is shown in Table 3.
When the detected frequencyifthe sync signalhaschanged, the totalnumber oflinesshouldbe
counted even through it is range identifiedfrequencyin the same mode.
4.2.2Out of range
This out of range mode is assumed when the frequencyout ofthe horizontal / verticalsignal is as
specified below.
Vertical frequency:56 ~76Hz.
Horizontal frequency:30 ~81.1KHz.
4.2.3Power save mode
The power save mode is assumed whenthe 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 themeasuring rangeof MST8111B.
If the vertical sync signal is outside the measuring range of MST8111B.

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AL1702
Table2videomode
PolarityMode
Resolution H-Freq
(KHz)
BandWidth
(MHz) HV
1720x400 (70Hz) 31.469 28.322 -+
2640x480 (59.94Hz) 31.469 25.175 --
3640x480 (66.67Hz) 3530.24--
4640x480 (72Hz) 37.861 31.5--
5640x480 (75Hz) 37.5 31.5--
6800x600 (56.25Hz) 35.156 36 ++
7800x600 (60Hz) 37.879 40 ++
8800x600 (72Hz) 48.077 50 ++
9800x600 (75Hz) 46.875 49.5++
10832x624 (74.55Hz) 49.722 57.28--
111024x768(60Hz)48.363 65 --
121024x768(70Hz)56.476 75 --
131024x768(75Hz)60.023 78.75++
141152x864 (75Hz)67.5 108++
151280x960(60Hz)60108++
161280x1024 (60Hz) 63.981 108++
171280x1024 (75Hz) 79.976 135++
Table3 theHsync,Vsync distinction
Indication
resolution
Distinction HsyncDistinctionVsync The fixed
mode
720 x400 30.5KHz fH 32.5KHz 69Hz fV 71Hz 1
640 x480 30.5KHz fH 32.5KHz 59Hz fV 61Hz 2
34KHz fH 36KHz 65.7Hz fV 67.7Hz 3
36.9KHz fH 38.9KHz 71.8Hz fV 73.8Hz 4
36.5KHz fH 38.5KHz 74Hz fV 76Hz 5
800 x600 34.2KHz fH 36.2KHz 55.3Hz fV 57.3Hz 6
36.9KHz fH 38.9KHz 59.3Hz fV 61.3Hz 7
47.1KHz fH 49.1KHz 71.2Hz fV 73.2Hz 8
45.9KHz fH 47.9KHz 74Hz fV 76Hz 9
832 x624 48.7KHz fH 50.7KHz 73.5Hz fV 75.5Hz 10
1024x768
47.4KHz fH 49.4KHz 59Hz fV 61Hz 11
55.5KHz fH 57.5KHz 69Hz fV 71Hz 12
59KHz fH 61KHz 74Hz fV 76Hz 13
1152x864 66.5KHz fH 68.5KHz 74Hz fV 76Hz 14
1280x960
59KHz fH 61KHz 59Hz fV 61Hz 15
1280 x1024
62.9KHz fH 64.9KHz 59Hz fV 61Hz 16
1280 x1024
79KHz fH 81KHz 74Hz fV 76Hz 17