No backlight + no keyboard backlight implies fuse problem?
テキスト:
I have had display problems, so I changed the backlight fuse on my Macbook Air. After that, there is still no display. The computer works fine otherwise, I can turn it on and hear sounds.
As of now I am wondering whether I soldered wrong, or whether the problem is with the backlight itself.
I also noticed that there is no keyboard backlight. Even if I hit the keyboard backlight keys, it doesn't light up.
-
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?
+
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?
EDIT: I did some measurements on the logic board. My interpretation of them is that everything seems fine, except the voltage divider for BKL_EN. For some reason, even though input voltage seems fine, and both resistors have correct resistance, divider output is slightly lower than it should be.
The only weird thing I notice, that could explain this value, is the fact that resistance rises slowly when I measure it. It starts at half the final value, and rises logarithmically for about 30 seconds.
Here are the measurements:
+
+
Global values
* PPBUS_G3H : 8.3V
+
* SMC_LID : 3.4 V
+
+
Driver output
* PPVOUT_SW_LCDBKLT : 8.43 V
* PPVOUT_SW_LCDBKLT_FB (at test point) : 8.4 V
* PPBUS_SW_LCDBKLT_PWR_SW : 8.46 V
-
* SMC_LID : 3.4 V
+
* PPBUS_SW_BKL (before L9701 inductance) : 8.32 V
+
* Output of inductance
+
** When measured in DC : 8.32 V
+
** When measured in AC : 17.5 V
+
* Feedback line connectivity check:
+
** By putting multimeter in diode mode, placing red probe on ground, and black probe on PPVOUT_SW_LCDBKLT, multimeter displays 510/512/515
+
*** A second measurement gave 530
+
+
BKL_EN circuit
+
* BKL_EN : 2.64 V
+
* PPBUS_SW_LCDBKLT_PWR : 8.43 V
+
** measured both at test point, and on resistor closest to driver
+
* Fuse : 8.43 V
+
* Resistors
+
** R9731 : 201 kOhms
+
** R9715 : 101 kOhms
+
** => theoretically BKL_EN should be : 2,72
+
+
Other driver inputs
* PP5V_S0_BKL : 5.17 V
* PP3V3_S0_BKL_VDDIO : 3.3 V
* BKL_PWM : 3.34 V
* LCD_BKL_PWM : 3.34 V
-
* BKL_EN : 2.64 V
-
* PPBUS_SW_LCDBKLT_PWR : 8.43 V
-
* Fuse : 8.43 V
-
* Resistors
-
** R9731 : 199.9 kOhm
-
** R9715 : 95.6 kOhm
-
** => theoretically BKL_EN should be : 2,72
-
* Feedback line connectivity check:
-
** By putting multimeter in diode mode, placing red probe on ground, and black probe on PPVOUT_SW_LCDBKLT, multimeter displays 500 when computer is off, -600 when it is on
No backlight + no keyboard backlight implies fuse problem?
テキスト:
I have had display problems, so I changed the backlight fuse on my Macbook Air. After that, there is still no display. The computer works fine otherwise, I can turn it on and hear sounds.
As of now I am wondering whether I soldered wrong, or whether the problem is with the backlight itself.
I also noticed that there is no keyboard backlight. Even if I hit the keyboard backlight keys, it doesn't light up.
-
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?
+
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?
+
+
EDIT: I did some measurements on the logic board. My interpretation of them is that everything seems fine, except the voltage divider for BKL_EN. For some reason, even though input voltage seems fine, and both resistors have correct resistance, divider output is slightly lower than it should be.
+
+
The only weird thing I notice, that could explain this value, is the fact that resistance rises slowly when I measure it. It starts at half the final value, and rises logarithmically for about 30 seconds.
+
+
Here are the measurements:
+
* PPBUS_G3H : 8.3V
+
* PPVOUT_SW_LCDBKLT : 8.43 V
+
* PPVOUT_SW_LCDBKLT_FB (at test point) : 8.4 V
+
* PPBUS_SW_LCDBKLT_PWR_SW : 8.46 V
+
* SMC_LID : 3.4 V
+
* PP5V_S0_BKL : 5.17 V
+
* PP3V3_S0_BKL_VDDIO : 3.3 V
+
* BKL_PWM : 3.34 V
+
* LCD_BKL_PWM : 3.34 V
+
* BKL_EN : 2.64 V
+
* PPBUS_SW_LCDBKLT_PWR : 8.43 V
+
* Fuse : 8.43 V
+
* Resistors
+
** R9731 : 199.9 kOhm
+
** R9715 : 95.6 kOhm
+
** => theoretically BKL_EN should be : 2,72
+
* Feedback line connectivity check:
+
** By putting multimeter in diode mode, placing red probe on ground, and black probe on PPVOUT_SW_LCDBKLT, multimeter displays 500 when computer is off, -600 when it is on
No backlight + no keyboard backlight implies fuse problem?
テキスト:
I have had display problems, so I changed the backlight fuse on my Macbook Air. After that, there is still no display. The computer works fine otherwise, I can turn it on and hear sounds.
As of now I am wondering whether I soldered wrong, or whether the problem is with the backlight itself.
I also noticed that there is no keyboard backlight. Even if I hit the keyboard backlight keys, it doesn't light up.
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?
No backlight + no keyboard backlight implies fuse problem?
テキスト:
I have had display problems, so I changed the backlight fuse on my Macbook Air. After that, there is still no display. The computer works fine otherwise, I can turn it on and hear sounds.
As of now I am wondering whether I soldered wrong, or whether the problem is with the backlight itself.
I also noticed that there is no keyboard backlight. Even if I hit the keyboard backlight keys, it doesn't light up.
I was wondering whether that means that my soldering is wrong, or not. Is the backlight fuse also "protecting" the keyboard backlight ?