TROUBLESHOOTING
Apple Macbook air A 1237 (820-2179) totaly death ,14.5 V already have in TPS 51120 pin 22(Vin) but no Vreg3 and Vreg5 output present .before claim TPS 51120 damage i check Vreg3 and Vreg5 LDO output by diode test buzzer 0001 ohm, test continuity to the ground also 0001 ohm positively there is a feed back on Vreg 5 line .pull tps 51120 out than inject 5V using PSU to finding shorted component on that line to save time and found Caps C 7604 become hot and replace with good one than put TPS 51120 again on place and Vreg3 present for 3.3V and Vreg5 present 5V.current monitoring on PSU goes up to 0.8a .it's mean board is switch on it self I put adapter of concerning hit sink fan not install yet to avoid chip and processor damage. after that ,test it again well fan running without switching .
Apple 820-2330 no boot post current usage 0.7amp ,detect-read-backup-erase-reprogram ,error on verifing -replace bios ic -reprograme with original backup.
Asus K42jr Rev 4.0 No display ,current usage 1.2amp checkingPLT_RST# present present for 3.3V .i dont touch any main bios firmware ,Vccore 1.1VS present, Vccram for ddr3 1,5V present VTT 0.75 present.Checking bypass checking SB_VCC cause PLTR_RST# PCH power good already present at the begining..Checking +AVDD_ATI 1.8V present,+A2VDD_ATI 3.3Vs Present ,+DPLL_VDDC_ATI 1,1VS also present ,no more suspect faulty fauld on Graphic chip checking Quad Mux/DeMux Bus Switch IC PI5C3257QE ,VCC present for +5VS no EDID_DAT_VGA and EDID_CLK_VGA for ATI M92 VGA CHIP ,no L_VDDEN output signal for 3.3V ,checking L_VDDEN_PCH enable signal from HM55 Southbridge not present .Reballing HM 55 L_VDDEN_PCH present and all missing signal for ATI M92 VGA CHIP present, L_VDDEN output signal for 3.3V for LVDS present .current usage 2.1amp
Hp DV 2 Quanta QL 6 Power Drop after switch on ,Identified Boot Device Inductors there are no feedback at all ,measuring any boot up device power rail by holding up avo meter on each inductors while switching on got all power need for 1 second before losing the power. checking VTT on PU 4(no inductor) also get 0.9VTT memory terminator before power drop. Checking +VGA1.1V(no inductor)on PU 5 =0V.checking PU5 Source +1.8V available, mainon VENable also present 3V.but VO(Voltage Out) for +VGA1.1V =0V.check for feedback got buzzer 0001ohm and pull up L37 to cut the line .short gone. checking on other L37 side pin feedback still presented .Inject voltage for 1V~2.0a Nvidia NB9M getting hot .concluding feedback coming from this chip pull up the chip with BGA Machine and check feedback again to make sure there is no other shorted on circuit evidently still have a feedback. inject again 1V~2.0a found C638 burned .pull it up shorted gone. Reball the chip with already removed and put it back .checking feedback again are gone .testing switch again power after switch running stable but no post. checking all boot device again all voltage rail presented. drain for induction by pressing power button for 40 second and change memory sodim just in case but still no post on external display current usage showed 1.4A.this should be a normal consumption on whole circuit for boot strap Start thinking failed on rebaling process before reiterate BGA procedure try to check with internal Led .evidently already display
Hp G 42 (AX2/7) AMD with SB 820 south bridge no post ,Current usage 0.7amp . missing PCI_RST and NB_PLTRST, with no check for SUS_C signal .than reball SB820 with no results. before decided to replace with new one, i check bat Cmos .got some case on AMD's wont response if bat cmos removed or on low power . .i found cmos on good condition and trace +AVBAT not reach into SB820 pin B1 and B2 through R469 ..wondering if this power missing motherboard should can't be switch on cause +AVBT should charging by +3VPCU with supply EC to activate micro controller .trace +AVBT found D23 diode no issue but +3VPCU present .it mean EC got +3VPCU .change D23 and got VDDBT_RTC_G to powered crystal input power to run clock system on SB. Check SUS_C again signal available for 3V.than current usage 1.2amp check on external display problem solve
Lenovo G400 La 9632P totally death check 20V is coming to supply SMPS PU 401 and Enable pin present for 3V but LDO 0V.lift PU 401 check there is a feed back on pin 5 LDO out .inject 3V KB 9012 become hot ,there is no possibility other component short on that line, lift KB 9012 feedback gone .Replace KB 9012 switch on 3V coming but no display .current usage only 0.2 amp on my PSU current monitor . I need to reprograme this KB 9012 for Lenono G400 LA 9632P using RT 809F programmer to flash EC Firmware to KB 9012 SLP_S3 and SLP_5 coming ,current usage 1.4Amp but still no display on external monitor ,put the laptop original Led current usage become 1.7Amp and boot up process working fine
Dell N 5010 Berry DG15 no display current usage 1.2amp ,usually this current consumption have been post except some thing wrong with random aces memory or Graphic chip. Starting checking +3.3V_RUN_VGA presented~+1.8V_RUN_VGA presented~+3.3V_RUN_VGA presented~+1.0V_RUN_VGA but Missing +1.5V_RUN, check switching N channel U4203 Source(input) pin available on pin 5,6,7,8 for 1,5VSUS and gate signal (switching trigger) pin 4 available for+1.5V_RUN_ENABLE .checking N channel Drain (output) got 0V before executed N channel damage checking if there is a feedback there, testing by buzzer (continuity)to the ground than i found a feedback .it's mean there is one or more shortage component on this line..Using PSU set 1,5V than inject maximal allowed value on this line found warm capacitor on C4208 ,pull them out and testing out side by buzzer 2 of pin with 0000ohm .replace with new one and testing again +1.5V_RUN present without changing Switching n channel U4203.Problem solve .
Note : Check any Voltage and signal missing before doing BGA reballing process .
Acer ZE 7 Missing LCDVCC3V no video for Led power change U 19 output pin 1 zero, beep pin 1 to ground there is beep value 0000ohm ,positive cause a feed back, inject 3V 1.5Amp found C310 very hot lift the caps short gone . test plug in power amd switch on U19 pin 1 output coming for 3.1V .plug in led problem solved
Acer AOD 270 Quanta ZE 7 switch on Led ligh on ,current usage 0.25amp ,no post ,no fan spinning Check +3VPCU and +VPCU on PL3 and PL 4 both are present ,check S5_ON 3.3V present,+5V present on PQ12 ,+5V on PQ22 pin 1 zero ,check PQ22 source pin 3 present for +3VPCU but no gate (MAIND) pin 2 not present ,this gate trigger should have 3V to pass source voltage into drain for +3V .so many usage on this missing voltage including +3.3V_PRIME_ON and stop +3VSUS coming
Toshiba C640 Manus 10 Totally death motherboard .ADP +19V couldn't reach ADP fet and SMPS VIN Sources to generate 3V and 5VALW.Opening schema by identified Jack power location code CN 600 page 6 and check adp+ voltage on jack 19V present ,trace D6005 19V ok check Q6002 sources pin 5,6,7,8 present for 19V no gate trigger present ,of course drain will not comes out .tray to inject 19V prom PSU 19V on Q6002 but no drain output .lift this N channel mosfet and replace with new one but drain wont comes out event having 19V gate driver injected. direct inject to Q6002 drain no shorted indication. Some fiture of this charger IC blocking ADP+ through Current sensor input positive (CSSP) by pushing analog ground to stop ADP+ entering the circuit doe over voltage protection .Checking Adapter current input (ACIN) on pin 19 Max 17435 available for 1.7V this is normal according Max 17435 datasheet .Checking Charger IC power good (ACOK 3.3V) not present ,LDO also zero volt and get 0ohm on that line ,inject 5V there Max 17435 become hot. lift max 17435 short gone ,replace Max 17435 .plug in adapter to check Q6002 drain saw led light already on ,it mean ALL VALW and 3V_5VALW already present .switch on Toshiba logo appear .
Asus K42 SV Board code K42JR no post ,Following no post procedure VCCore present 1.1VS ,checking Memory Power 1.5VS present but no VTT present ,Checking PU 9103 UP7711U8 ddr voltage regulator Voltage control(VCNTL) present for 5VS ,Vin present for 1.5V but no VOUT on pin 4 .testing connecting to the ground 0ohm ,lift the IC short gone ,replace with new one measuring VOUT 0.75VTT coming .
Toshiba L645D Quanta TE3 external monitor display ,internal no display look like a Dim display problem but flashlight no sign of life .check LVDS connector CN3 ,LCD_BK_PWR 19V present ,DISPON 3VS present ,other +3V present ,no LCDVCC and LCD_VADJ ,no output from E9 and F7 pin on ATi 216-0752001 ,it may cause BGA oxidized .lift the chip and testing ground continuity on both pad no shorted on that pad .Reball the chip still no result but current usage increase
from 1.2amp to 1,4amp .check LCD_VADJ has 1.8V there but still no LCDVCC. Replace Ati 216-0752001 problem solved .
Compaq CQ41 Compal LA 4107 No display current usage 0.7amp to 0.9amp not stable ,missing PLTRST output D5 HM 55 ,measuring point on U2 ,reprograme Main bios firmware PLTRST present .
Dell inspiron N4050 model DV14 HR MB dual graphic having problem with AMD/ATI 216-0809024 ,after lifted the chip there are some active pad missing .it is useless to reball or replace a chip .Thinking of keep removing AMD 216-0809024 chip trying to editing Main bios to deactivated AMD chip and using HM67 only using Hex editor .as we know intel HM 67 has a fiture for dedicate intel graphic HD 3000 on this South bridge and Binggo it work but intel driver wont detect on windows .While trying to have some more information about using HEX ,i found the other series of Dell 4050 using single chip intel HM 67 chip .backup original main bios of DV4HR version 01M and compare the file and found some difference on Address 004000 to 004D40 .just incase this happen again on the other series. Well it work fine after QC test for last 4hours.
Toshiba C640 CT10 no power missing +V3LA and +V5A ,checking Tps 51125 page 8 inventec calcutta 10 mb ,no ground feedback on L6200 and L6201 ,checking TPS 51125 SMPS IC regulator input Vin (pin 16) presented 19V,checking output LDO Vreg3 (pin8) presented 3.3V,checking VREG5 (pin 17) presented +V5LA ...checking Enable input Entrip1 (pin 1) and Entrip2 (pin 6) not present..tracking +V5LA to Logic Gate IC U6100 voltage source Pin 3(VCC) presented 5V,pin 5(MR) presented 5V but output reset pin 1 not present .checking ground feedback on pin 1 no ground feedback, checking gate VSEN pin 4 not present .this Vsent should be present 3.3V as a trigger gate to make output reset pin 1 present to powering +5AUXON source...check Vsen (pin 4) sources from +VBAT 19V adapter usage resistive by R6104 and R6103 it should present 3,3V but 0V present ,checking R6104 it should 510k but found immeasurable, checking R6103 also immeasurable, changing both Resistor got 3.3V on VSEN pin, checking pin 1 (reset) present for 5V ,checking +V5AUXON also present for 5V ,back to SMPS IC D6201 input +V5AUXON present for 5V on pin 3,checking pin 1 and 2 present for 1.2V..it mean Entrip1 and Entrip2 already present. checking SMPS inductor L6200 and L6201 +V3LA and +V5A present .Problem Solved.
Acer V5-471 Husk Petra rev2 power switching problem ,current usage 0.013amp Checking SMPS inductors PL 4101 and PL 4102 3D3V and 5V presented ,checking RSMRST 3.3V presented, checking KBC_PWRBTN on PWRCN1 (Voltage switch button) present for 3.3V.shorted VSB direct to the ground no response, trace to NPCE 885P pin 93,shorted to ground current response from 0.013 to 0.9amp and power on and display .check R2757 KBC_PWRBTN# to KBC_PWRBTN#R resistance 470K was ok ,no more tracking point on schema, it may some conductor broken ,jumper from R2757 pin2 direct to PWRCN1(pin3) problem solved.
Acer 4738 Quanta ZQ9 Totally death .Current usage 0008 amp .Open Quanta ZQ9 schematic on Page 37 to measure adp+ circuit need .This acer using 19V adp+ Voltage .Checking PQ13 N channel source pin 5,6,7,8 19V present.PQ 14 N channel source same way to check PQ 13 .This both upper n channel are power source for 3V and 5V_ALW need. RT 8206 (dc pwr sply) controlling trigger gate driver trough pin 4 gate PQ13 and PQ14 and supply 3V_and 5V motherboard power need requirement to live..There is no trigger for both of 3V_5V system it mean there are no power for VSB(voltage switch button) ,Bios ic,EC ,SB .this motherboard even can't switch .
Analyses goes to RT 8206B as a gate trigger .checking main power input for RT8206B trough VIN pin 5 (19V present) checking ONLDO input pin 4 (9V present) it mean all power input available for this IC. checking LDO output Zero .in normal condition if VIN and ONLDO presented LDO should get output for 5V.this voltage become VL signal enable to activated 5V_EN and 3V_EN .without this gate triger for 3V_5V system will not present .suspected this IC damage take off from circuit board before replace with a new one checking LDO output for feedback...test continuity 0000 ohm to the ground..using PSU set 5V started pushing current 1amp and found caps PC70 become warm and checking continuity positive this PC70 cause a feedback and hold LDO output .replace caps and put back RT8206B .Testing both gate N channel 3V and 5V trigger available .checking PL13 5V_ALW present ,checking PL 14 3V_ALW present .Problem Solved.
Apple Macbook air A 1237 (820-2179) totaly death ,14.5 V already have in TPS 51120 pin 22(Vin) but no Vreg3 and Vreg5 output present .before claim TPS 51120 damage i check Vreg3 and Vreg5 LDO output by diode test buzzer 0001 ohm, test continuity to the ground also 0001 ohm positively there is a feed back on Vreg 5 line .pull tps 51120 out than inject 5V using PSU to finding shorted component on that line to save time and found Caps C 7604 become hot and replace with good one than put TPS 51120 again on place and Vreg3 present for 3.3V and Vreg5 present 5V.current monitoring on PSU goes up to 0.8a .it's mean board is switch on it self I put adapter of concerning hit sink fan not install yet to avoid chip and processor damage. after that ,test it again well fan running without switching .
Apple 820-2330 no boot post current usage 0.7amp ,detect-read-backup-erase-reprogram ,error on verifing -replace bios ic -reprograme with original backup.
Asus K42jr Rev 4.0 No display ,current usage 1.2amp checkingPLT_RST# present present for 3.3V .i dont touch any main bios firmware ,Vccore 1.1VS present, Vccram for ddr3 1,5V present VTT 0.75 present.Checking bypass checking SB_VCC cause PLTR_RST# PCH power good already present at the begining..Checking +AVDD_ATI 1.8V present,+A2VDD_ATI 3.3Vs Present ,+DPLL_VDDC_ATI 1,1VS also present ,no more suspect faulty fauld on Graphic chip checking Quad Mux/DeMux Bus Switch IC PI5C3257QE ,VCC present for +5VS no EDID_DAT_VGA and EDID_CLK_VGA for ATI M92 VGA CHIP ,no L_VDDEN output signal for 3.3V ,checking L_VDDEN_PCH enable signal from HM55 Southbridge not present .Reballing HM 55 L_VDDEN_PCH present and all missing signal for ATI M92 VGA CHIP present, L_VDDEN output signal for 3.3V for LVDS present .current usage 2.1amp
Hp DV 2 Quanta QL 6 Power Drop after switch on ,Identified Boot Device Inductors there are no feedback at all ,measuring any boot up device power rail by holding up avo meter on each inductors while switching on got all power need for 1 second before losing the power. checking VTT on PU 4(no inductor) also get 0.9VTT memory terminator before power drop. Checking +VGA1.1V(no inductor)on PU 5 =0V.checking PU5 Source +1.8V available, mainon VENable also present 3V.but VO(Voltage Out) for +VGA1.1V =0V.check for feedback got buzzer 0001ohm and pull up L37 to cut the line .short gone. checking on other L37 side pin feedback still presented .Inject voltage for 1V~2.0a Nvidia NB9M getting hot .concluding feedback coming from this chip pull up the chip with BGA Machine and check feedback again to make sure there is no other shorted on circuit evidently still have a feedback. inject again 1V~2.0a found C638 burned .pull it up shorted gone. Reball the chip with already removed and put it back .checking feedback again are gone .testing switch again power after switch running stable but no post. checking all boot device again all voltage rail presented. drain for induction by pressing power button for 40 second and change memory sodim just in case but still no post on external display current usage showed 1.4A.this should be a normal consumption on whole circuit for boot strap Start thinking failed on rebaling process before reiterate BGA procedure try to check with internal Led .evidently already display
Hp G 42 (AX2/7) AMD with SB 820 south bridge no post ,Current usage 0.7amp . missing PCI_RST and NB_PLTRST, with no check for SUS_C signal .than reball SB820 with no results. before decided to replace with new one, i check bat Cmos .got some case on AMD's wont response if bat cmos removed or on low power . .i found cmos on good condition and trace +AVBAT not reach into SB820 pin B1 and B2 through R469 ..wondering if this power missing motherboard should can't be switch on cause +AVBT should charging by +3VPCU with supply EC to activate micro controller .trace +AVBT found D23 diode no issue but +3VPCU present .it mean EC got +3VPCU .change D23 and got VDDBT_RTC_G to powered crystal input power to run clock system on SB. Check SUS_C again signal available for 3V.than current usage 1.2amp check on external display problem solve
Lenovo G400 La 9632P totally death check 20V is coming to supply SMPS PU 401 and Enable pin present for 3V but LDO 0V.lift PU 401 check there is a feed back on pin 5 LDO out .inject 3V KB 9012 become hot ,there is no possibility other component short on that line, lift KB 9012 feedback gone .Replace KB 9012 switch on 3V coming but no display .current usage only 0.2 amp on my PSU current monitor . I need to reprograme this KB 9012 for Lenono G400 LA 9632P using RT 809F programmer to flash EC Firmware to KB 9012 SLP_S3 and SLP_5 coming ,current usage 1.4Amp but still no display on external monitor ,put the laptop original Led current usage become 1.7Amp and boot up process working fine
Dell N 5010 Berry DG15 no display current usage 1.2amp ,usually this current consumption have been post except some thing wrong with random aces memory or Graphic chip. Starting checking +3.3V_RUN_VGA presented~+1.8V_RUN_VGA presented~+3.3V_RUN_VGA presented~+1.0V_RUN_VGA but Missing +1.5V_RUN, check switching N channel U4203 Source(input) pin available on pin 5,6,7,8 for 1,5VSUS and gate signal (switching trigger) pin 4 available for+1.5V_RUN_ENABLE .checking N channel Drain (output) got 0V before executed N channel damage checking if there is a feedback there, testing by buzzer (continuity)to the ground than i found a feedback .it's mean there is one or more shortage component on this line..Using PSU set 1,5V than inject maximal allowed value on this line found warm capacitor on C4208 ,pull them out and testing out side by buzzer 2 of pin with 0000ohm .replace with new one and testing again +1.5V_RUN present without changing Switching n channel U4203.Problem solve .
Note : Check any Voltage and signal missing before doing BGA reballing process .
Acer ZE 7 Missing LCDVCC3V no video for Led power change U 19 output pin 1 zero, beep pin 1 to ground there is beep value 0000ohm ,positive cause a feed back, inject 3V 1.5Amp found C310 very hot lift the caps short gone . test plug in power amd switch on U19 pin 1 output coming for 3.1V .plug in led problem solved
Acer AOD 270 Quanta ZE 7 switch on Led ligh on ,current usage 0.25amp ,no post ,no fan spinning Check +3VPCU and +VPCU on PL3 and PL 4 both are present ,check S5_ON 3.3V present,+5V present on PQ12 ,+5V on PQ22 pin 1 zero ,check PQ22 source pin 3 present for +3VPCU but no gate (MAIND) pin 2 not present ,this gate trigger should have 3V to pass source voltage into drain for +3V .so many usage on this missing voltage including +3.3V_PRIME_ON and stop +3VSUS coming
Toshiba C640 Manus 10 Totally death motherboard .ADP +19V couldn't reach ADP fet and SMPS VIN Sources to generate 3V and 5VALW.Opening schema by identified Jack power location code CN 600 page 6 and check adp+ voltage on jack 19V present ,trace D6005 19V ok check Q6002 sources pin 5,6,7,8 present for 19V no gate trigger present ,of course drain will not comes out .tray to inject 19V prom PSU 19V on Q6002 but no drain output .lift this N channel mosfet and replace with new one but drain wont comes out event having 19V gate driver injected. direct inject to Q6002 drain no shorted indication. Some fiture of this charger IC blocking ADP+ through Current sensor input positive (CSSP) by pushing analog ground to stop ADP+ entering the circuit doe over voltage protection .Checking Adapter current input (ACIN) on pin 19 Max 17435 available for 1.7V this is normal according Max 17435 datasheet .Checking Charger IC power good (ACOK 3.3V) not present ,LDO also zero volt and get 0ohm on that line ,inject 5V there Max 17435 become hot. lift max 17435 short gone ,replace Max 17435 .plug in adapter to check Q6002 drain saw led light already on ,it mean ALL VALW and 3V_5VALW already present .switch on Toshiba logo appear .
Asus K42 SV Board code K42JR no post ,Following no post procedure VCCore present 1.1VS ,checking Memory Power 1.5VS present but no VTT present ,Checking PU 9103 UP7711U8 ddr voltage regulator Voltage control(VCNTL) present for 5VS ,Vin present for 1.5V but no VOUT on pin 4 .testing connecting to the ground 0ohm ,lift the IC short gone ,replace with new one measuring VOUT 0.75VTT coming .
Toshiba L645D Quanta TE3 external monitor display ,internal no display look like a Dim display problem but flashlight no sign of life .check LVDS connector CN3 ,LCD_BK_PWR 19V present ,DISPON 3VS present ,other +3V present ,no LCDVCC and LCD_VADJ ,no output from E9 and F7 pin on ATi 216-0752001 ,it may cause BGA oxidized .lift the chip and testing ground continuity on both pad no shorted on that pad .Reball the chip still no result but current usage increase
from 1.2amp to 1,4amp .check LCD_VADJ has 1.8V there but still no LCDVCC. Replace Ati 216-0752001 problem solved .
Compaq CQ41 Compal LA 4107 No display current usage 0.7amp to 0.9amp not stable ,missing PLTRST output D5 HM 55 ,measuring point on U2 ,reprograme Main bios firmware PLTRST present .
Dell inspiron N4050 model DV14 HR MB dual graphic having problem with AMD/ATI 216-0809024 ,after lifted the chip there are some active pad missing .it is useless to reball or replace a chip .Thinking of keep removing AMD 216-0809024 chip trying to editing Main bios to deactivated AMD chip and using HM67 only using Hex editor .as we know intel HM 67 has a fiture for dedicate intel graphic HD 3000 on this South bridge and Binggo it work but intel driver wont detect on windows .While trying to have some more information about using HEX ,i found the other series of Dell 4050 using single chip intel HM 67 chip .backup original main bios of DV4HR version 01M and compare the file and found some difference on Address 004000 to 004D40 .just incase this happen again on the other series. Well it work fine after QC test for last 4hours.
Toshiba C640 CT10 no power missing +V3LA and +V5A ,checking Tps 51125 page 8 inventec calcutta 10 mb ,no ground feedback on L6200 and L6201 ,checking TPS 51125 SMPS IC regulator input Vin (pin 16) presented 19V,checking output LDO Vreg3 (pin8) presented 3.3V,checking VREG5 (pin 17) presented +V5LA ...checking Enable input Entrip1 (pin 1) and Entrip2 (pin 6) not present..tracking +V5LA to Logic Gate IC U6100 voltage source Pin 3(VCC) presented 5V,pin 5(MR) presented 5V but output reset pin 1 not present .checking ground feedback on pin 1 no ground feedback, checking gate VSEN pin 4 not present .this Vsent should be present 3.3V as a trigger gate to make output reset pin 1 present to powering +5AUXON source...check Vsen (pin 4) sources from +VBAT 19V adapter usage resistive by R6104 and R6103 it should present 3,3V but 0V present ,checking R6104 it should 510k but found immeasurable, checking R6103 also immeasurable, changing both Resistor got 3.3V on VSEN pin, checking pin 1 (reset) present for 5V ,checking +V5AUXON also present for 5V ,back to SMPS IC D6201 input +V5AUXON present for 5V on pin 3,checking pin 1 and 2 present for 1.2V..it mean Entrip1 and Entrip2 already present. checking SMPS inductor L6200 and L6201 +V3LA and +V5A present .Problem Solved.
Acer V5-471 Husk Petra rev2 power switching problem ,current usage 0.013amp Checking SMPS inductors PL 4101 and PL 4102 3D3V and 5V presented ,checking RSMRST 3.3V presented, checking KBC_PWRBTN on PWRCN1 (Voltage switch button) present for 3.3V.shorted VSB direct to the ground no response, trace to NPCE 885P pin 93,shorted to ground current response from 0.013 to 0.9amp and power on and display .check R2757 KBC_PWRBTN# to KBC_PWRBTN#R resistance 470K was ok ,no more tracking point on schema, it may some conductor broken ,jumper from R2757 pin2 direct to PWRCN1(pin3) problem solved.
Acer 4738 Quanta ZQ9 Totally death .Current usage 0008 amp .Open Quanta ZQ9 schematic on Page 37 to measure adp+ circuit need .This acer using 19V adp+ Voltage .Checking PQ13 N channel source pin 5,6,7,8 19V present.PQ 14 N channel source same way to check PQ 13 .This both upper n channel are power source for 3V and 5V_ALW need. RT 8206 (dc pwr sply) controlling trigger gate driver trough pin 4 gate PQ13 and PQ14 and supply 3V_and 5V motherboard power need requirement to live..There is no trigger for both of 3V_5V system it mean there are no power for VSB(voltage switch button) ,Bios ic,EC ,SB .this motherboard even can't switch .
Analyses goes to RT 8206B as a gate trigger .checking main power input for RT8206B trough VIN pin 5 (19V present) checking ONLDO input pin 4 (9V present) it mean all power input available for this IC. checking LDO output Zero .in normal condition if VIN and ONLDO presented LDO should get output for 5V.this voltage become VL signal enable to activated 5V_EN and 3V_EN .without this gate triger for 3V_5V system will not present .suspected this IC damage take off from circuit board before replace with a new one checking LDO output for feedback...test continuity 0000 ohm to the ground..using PSU set 5V started pushing current 1amp and found caps PC70 become warm and checking continuity positive this PC70 cause a feedback and hold LDO output .replace caps and put back RT8206B .Testing both gate N channel 3V and 5V trigger available .checking PL13 5V_ALW present ,checking PL 14 3V_ALW present .Problem Solved.
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