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MBP 820-2936 dont backlight
- Thread starter lincev
- Start date
First of all, welcome to the forum!
"I have 12v"
Please, post exact voltage; 12.2V and 12.5V is totally different thing!
Do you get image, only missing backlight?
USB activity confirmed for sure?
"I have 12v"
Please, post exact voltage; 12.2V and 12.5V is totally different thing!
Do you get image, only missing backlight?
USB activity confirmed for sure?
Welcome ! sorry im rude ! ok sorry
I have measured again and in all the points I have 12.5.
Rookie mistakes ...
I have image. Checked with a flick behind the screen in the apple logo I can see the question folder.
USB activity<--- EDIT: yes I have tried with an external monitor and the USB port works.
I have measured again and in all the points I have 12.5.
Rookie mistakes ...
I have image. Checked with a flick behind the screen in the apple logo I can see the question folder.
USB activity<--- EDIT: yes I have tried with an external monitor and the USB port works.
Last edited:
OK, then your problem is only backlight related.
Check first LCD_BKLT_EN and BKLT_PLT_RST_L.
Also post diode mode to ground at both pins of D9701 (red probe at ground); w/ and w/o LCD connected.
Inspect U9701 for corrosion, especially A5 ball.
Check first LCD_BKLT_EN and BKLT_PLT_RST_L.
Also post diode mode to ground at both pins of D9701 (red probe at ground); w/ and w/o LCD connected.
Inspect U9701 for corrosion, especially A5 ball.
LCD_BKLT_EN = 0v
BKLT_PLT_RST_L = 3.25v
D9701 w/o LCD value mode diode both pins 150 (red probe at ground); Pin1 386 Pin2 562
w/ LCD both pins 160 (red probe at ground) Pin1 and pin2 continuity
Inspect U9701 for corrosion, especially A5 ball. ---> This component is new. I asked a friend with great skill as an air welder to replace this component.
PPVOUT_SW_LCDBKLT_FB = 12.42v
BKLT_PLT_RST_L = 3.25v
D9701 w/o LCD value mode diode both pins 150 (red probe at ground); Pin1 386 Pin2 562
w/ LCD both pins 160 (red probe at ground) Pin1 and pin2 continuity
Inspect U9701 for corrosion, especially A5 ball. ---> This component is new. I asked a friend with great skill as an air welder to replace this component.
PPVOUT_SW_LCDBKLT_FB = 12.42v
"Q9706 pin 1,2,5 and 6 I do not have 12v.
-----------------------
LCD_BKLT_EN = 0v
--------------------
PPVOUT_SW_LCDBKLT_FB = 12.42v"
I force me to understand how this is possible...
We need accurate information, or we cannot help.
"w/ LCD both pins 160 (red probe at ground) Pin1 and pin2 continuity"
What this mean, D9701 measures short between pins?
-----------------------
LCD_BKLT_EN = 0v
--------------------
PPVOUT_SW_LCDBKLT_FB = 12.42v"
I force me to understand how this is possible...
We need accurate information, or we cannot help.
"w/ LCD both pins 160 (red probe at ground) Pin1 and pin2 continuity"
What this mean, D9701 measures short between pins?
Ok first thing thanks for your patience.
I did the measurements without a screen connected, I think that was my error for the measurements.
I have measured again with LCD connected and Q9706 Pin 1 2 5 and 6 = 12.5v
The measurements for D9701 I understand that I must put the red lead of the tester to ground and the black lead on pins 1 and 2 of the component. I'm confused?
I did the measurements without a screen connected, I think that was my error for the measurements.
I have measured again with LCD connected and Q9706 Pin 1 2 5 and 6 = 12.5v
The measurements for D9701 I understand that I must put the red lead of the tester to ground and the black lead on pins 1 and 2 of the component. I'm confused?
Yes, diode mode always with red probe on ground; but no power applied.
Now post BKL_EN/PWM.
Now post BKL_EN/PWM.
but no power applied. (I don't know it sorry im very noob)
D9701 w/o LCD value mode diode both pins 150 (red probe at ground);
w/ LCD pin1 425 pin2 643 both pines 187
w/o LCD pin1 424 pin2 641 both pines 185
U9701 BKL_EN and BKL_PWM I can't make measurements, I think the board has died or I made a mistake. Now no fan spin and sometimes it appears green light. I think it would be better to buy a reconditioned ebay.
D9701 w/o LCD value mode diode both pins 150 (red probe at ground);
w/ LCD pin1 425 pin2 643 both pines 187
w/o LCD pin1 424 pin2 641 both pines 185
U9701 BKL_EN and BKL_PWM I can't make measurements, I think the board has died or I made a mistake. Now no fan spin and sometimes it appears green light. I think it would be better to buy a reconditioned ebay.
If board had image before, shouldn't give up so fast.
You are absolutely right. I have cleaned the board again and now the green light remains but the fan does not respond. I've seen a post that talks about the U2600 component but mine seems fine.
Should I open a new post with this symptom? and continue this once the computer works again?
Should I open a new post with this symptom? and continue this once the computer works again?
Continue here.
Post basic voltages and signalfs from power on sequence.
Any history available for this board?
Post basic voltages and signalfs from power on sequence.
Any history available for this board?
It works fine until one day it ran out of battery and did not turn on the screen again. It has no liquid damage. It could be used with an external screen.
You needed this to help me. I do not know if I have forgotten to put some measure.
PPBUS_G3H = 12.5
PPVIN_G3H_P3V3G3H = 15V
PPBUS_S5_HS_COMPUTING_ISNS = 12.5 V
PPDCIN_G3H = 16.7V
PP3V42_G3H = 3.42V
PPVRTC_G3H = 3.42V
PP5V_S5 = 12.5V
PP5V_S3 = 0V
PP5V_S0 = 0V
PP3V3_S5 = 0V change 2,3 change 3,2 all time don’t stop
PP3V3_SUS = 0V
PP3V3_S4 = 0V change 2 change 3,2 all time don’t stop
PP1V8_S0 = 0V
PP1V5_S0 = 0V
PP1V05_SUS = 0V
You needed this to help me. I do not know if I have forgotten to put some measure.
PPBUS_G3H = 12.5
PPVIN_G3H_P3V3G3H = 15V
PPBUS_S5_HS_COMPUTING_ISNS = 12.5 V
PPDCIN_G3H = 16.7V
PP3V42_G3H = 3.42V
PPVRTC_G3H = 3.42V
PP5V_S5 = 12.5V
PP5V_S3 = 0V
PP5V_S0 = 0V
PP3V3_S5 = 0V change 2,3 change 3,2 all time don’t stop
PP3V3_SUS = 0V
PP3V3_S4 = 0V change 2 change 3,2 all time don’t stop
PP1V8_S0 = 0V
PP1V5_S0 = 0V
PP1V05_SUS = 0V
"PPBUS_G3H = 12.5
------------------
PPBUS_S5_HS_COMPUTING_ISNS = 12.5 V"
Try to understand a schematic.
Do not waste time measuring the same power rail in different points.
Post PM_BATLOW_L, PM_DSW_PWRGD, PCH_DSWVRMEN and PCH's RTC signals; 4, in page 16.
------------------
PPBUS_S5_HS_COMPUTING_ISNS = 12.5 V"
Try to understand a schematic.
Do not waste time measuring the same power rail in different points.
Post PM_BATLOW_L, PM_DSW_PWRGD, PCH_DSWVRMEN and PCH's RTC signals; 4, in page 16.
sorry for delay I've been very sick.
PM_BATLOW_L= 0v
PM_DSW_PWRGD= 0v 1,2v 3,2v flash
PCH_DSWVRMEN= 3.13v / 3.28 change flash
this part PCH's RTC signals; 4, in page 16. I don't understand. I beg your forgiveness but I don't understand what I should do with those signs. Refers to page 16 of the pdf files or at the bottom where the logo appears that puts page 16
PM_BATLOW_L= 0v
PM_DSW_PWRGD= 0v 1,2v 3,2v flash
PCH_DSWVRMEN= 3.13v / 3.28 change flash
this part PCH's RTC signals; 4, in page 16. I don't understand. I beg your forgiveness but I don't understand what I should do with those signs. Refers to page 16 of the pdf files or at the bottom where the logo appears that puts page 16
Page 16, inside PCH you can see RTC block marked.
There are 4 signals, apart of CLK.
Shouldn't be a problem there, as the board try to start (pulses).
Try to start in SMC bypass mode.
There are 4 signals, apart of CLK.
Shouldn't be a problem there, as the board try to start (pulses).
Try to start in SMC bypass mode.