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Current version by: oldturkey03 ,

Text:

Jason, this is not as easy as just recommending a certain part that has failed. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Just because the power /sound/etc. may be there, you can also not rule out the power supply. It may not supply the power to the LED backlight. You will need to check on that as well, take a good luck on the logic board. There should also be a fuse for the backlight, which may have failed. Post a couple of hi-res images of your logic board with your question, so we may look at it and see if we can come up with something more concrete. I would also suggest that you try the Apple Deep Dive for Blank / No Video, No Backlight:
 
Check Result Action Code
 
1. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
1. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
connectors into a known good, supported, powered-up portable. Verify display’s USB
 
hub and built-in camera are listed in the System Profiler’s USB device tree.
 
Yes
 
Power is available to the display logic board, and USB communication working.
 
Go to step 2.
 
No
 
Go to Dead Unit/No Power.
 
2. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
2. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
 
Yes
 
LCD is powered and detected by system. Go to step 7.
 
No
 
Suspected no power to LCD panel or no DisplayPort connection with system. Go
Suspected no power to LCD panel or no DisplayPort connection with system. Go
to step 3.
 
3. Remove glass and LCD panel screws, slightly pivot LCD panel and verify that the internal DisplayPort cable (part of all-inone cable) and function cable are fully connected to LCD panel and logic board.
 
Yes
 
Go to step 4.
 
No
 
Reseat DisplayPort connection to LCD panel and/or function cable connections between logic board and LCD panel and retest.
Reseat DisplayPort connection to LCD panel and/or function cable connections between logic board and LCD panel and retest.
If issue persists go to step 4.
 
For any damaged cable, replace affected cable before testing again:
 
- all-in-one cable.
 
- function cable.
 
4. Unplug and replug Mini DisplayPort connector into a known-good, supported,
powered-up
powered-up
portable system and monitor the portable’s display. Verify that the
powered-up
powered-up
portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
 
Yes
 
LCD is powered and detected by system. Go to step 7.
 
No
 
Suspect no power to LCD. Replace function cable and retest. If issue persists go to
Suspect no power to LCD. Replace function cable and retest. If issue persists go to
step 5.
 
5. Replace all-in-one cable and reinstall LCD. Unplug and replug the Mini DisplayPort
 
connector into a knowngood, supported, powered-up portable system and monitor
 
the portable’s display. Verify that the portable’s display briefly turns off then back on.
 
Yes
 
LCD panel powered and detected by system. Go to step 7.
 
No
 
LCD panel still not detected by system. Suspect no LCD power from logic board.
 
Go to step 6.
 
6. Replace logic board and reinstall LCD. Unplug and replug the Mini DisplayPort
 
connector into a knowngood, supported, powered-up portable system and monitor
 
the portable’s display. Verify that the portable’s display briefly turns off then back on.
 
Yes
 
LCD panel powered and detected by system. Go to step 7.
 
No
 
LCD panel still not detected by system with replaced function cable, all-in-one cable and logic board. Suspect LCD panel video input damage.
 
Replace LCD panel.
 
7. If the Blank/No Video/No Backlight issue persists, darken room and connect to a knowngood supported system. Verify backlight is present by looking for faint glow from display.
 
Yes
 
LCD panel powered, detected by system and backlight is ON but there is no video on LCD. Replace LCD panel.
 
No
 
LCD panel is detected by system but no backlight. Check whether video is present on LCD. Go to step 8.
 
8. Shine bright (low heat) flashlight into the front of the LCD. and verify if any image is
being displayed.
 
Yes
 
Video is present, so issue is only with missing backlight. Go to step 9.
 
No
 
No image displayed on LCD Replace LCD panel.
 
9. Remove glass and LCD panel screws, lift LCD panel to verify that the function cable, and LED backlight driver cable connections are secure. See Functional Overview.
 
Yes
 
If connections are OK and secure and there is still no backlight, go to step 10.
 
No
 
If any cable is damaged, replace affected cable and retest:
 
- function cable
 
- LED backlight driver cable (part of LCD panel)
 
10. Remove LCD panel. Set digital multimeter to DC and correct range, and verify that a 23.3–25.7 V DC voltage is present between logic board test point (24 V DC) and chassis ground (GND).
 
Yes
 
24 V DC power for backlight is present on logic board, but no backlight. Suspect no
 
V-sync signal coming to logic board. Go to step 11.
 
No
 
No 24 V DC present for LED backlight power. Replace power supply.
 
11. Replace function cable and retest. Verify that the no backlight issue is fixed.
 
Yes
 
Defective function cable prevented backlight from being enabled by logic board.
 
No
 
Go to step 12.
 
12. Verify if the LED backlight driver cable (part of the LCD panel) has any signs of pinched or shorted wires. Also remove the logic board and verify if one or more of the three square inductors or adjacent components on top of board show signs of overheating.
 
Yes
 
LED backlight driver cable on LCD panel found damaged. Replace LCD panel, (make
 
sure that you don’t pinch the LED driver cable from LCD panel) and retest. If the no backlight issue persists after LCD panel replacement, replace logic board (LED backlight output from logic board had been damaged by shorted cable.)
 
No
 
Suspect no LED backlight output from logic board: go to step 12.
 
13. Replace logic board and verify that the no backlight issue is fixed.
 
Yes
 
Defective logic board LED backlight driver output.
 
No
 
Replace LCD panel.
 
Before you go and replace anything let us know what you found. Hope this helps, good luck.

Status:

open

Edit by: oldturkey03 ,

Text:

Jason, this is not as easy as just recommending a certain part that has failed. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Just because the power /sound/etc. may be there, you can also not rule out the power supply. It may not supply the power to the LED backlight. You will need to check on that as well, take a good luck on the logic board. There should also be a fuse for the backlight, which may have failed. Post a couple of hi-res images of your logic board with your question, so we may look at it and see if we can come up with something more concrete. I would also suggest that you try the Apple Deep Dive for Blank / No Video, No Backlight:
 
Check Result Action Code
1
1
. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
1
1
. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
connectors into a known good, supported, powered-up portable. Verify display’s USB
hub and built-in camera are listed in the System Profiler’s USB device tree.
Yes
Yes
Yes
Yes
Power is available to the display logic board, and USB communication working.
 
Go to step 2.
No
No
No
No
Go to Dead Unit/No Power.
2
2
. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
2
2
. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
Yes
Yes
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspected

No

Suspected
no power to LCD panel or no DisplayPort connection with system. Go
No
Suspected

No

Suspected
no power to LCD panel or no DisplayPort connection with system. Go
to step 3.
 
3. Remove glass and LCD panel screws, slightly pivot LCD panel and verify that the internal DisplayPort cable (part of all-inone cable) and function cable are fully connected to LCD panel and logic board.
Yes
Yes
Yes
Yes
Go to step 4.
No
Reseat

No

Reseat
DisplayPort connection to LCD panel and/or function cable connections between
logic
logic board and LCD panel and retest.
No
Reseat

No

Reseat
DisplayPort connection to LCD panel and/or function cable connections between
logic
logic board and LCD panel and retest.
If issue persists go to step 4.
 
For any damaged cable, replace affected cable before testing again:
 
- all-in-one cable.
 
- function cable.
 
4. Unplug and replug Mini DisplayPort connector into a known-good, supported,
powered-up portable system and monitor the portable’s display. Verify that the
powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
Yes
Yes
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspect

No

Suspect
no power to LCD. Replace function cable and retest. If issue persists go to
No
Suspect

No

Suspect
no power to LCD. Replace function cable and retest. If issue persists go to
step 5.
 
5. Replace all-in-one cable and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
Yes
Yes
Yes
LCD panel powered and detected by system. Go to step 7.
No
No
No
No
LCD panel still not detected by system. Suspect no LCD power from logic board.
Go to step 6.
 
6. Replace logic board and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
Yes
Yes
Yes
LCD panel powered and detected by system. Go to step 7.
No
No
No
No
LCD panel still not detected by system with replaced function cable, all-in-one cable and logic board. Suspect LCD panel video input damage.
 
Replace LCD panel.
 
7. If the Blank/No Video/No Backlight issue persists, darken room and connect to a knowngood supported system. Verify backlight is present by looking for faint glow from display.
Yes
Yes
Yes
Yes
LCD panel powered, detected by system and backlight is ON but there is no video on LCD. Replace LCD panel.
No
No
No
No
LCD panel is detected by system but no backlight. Check whether video is present on LCD. Go to step 8.
 
8. Shine bright (low heat) flashlight into the front of the LCD. and verify if any image is
being displayed.
Yes
Yes
Yes
Yes
Video is present, so issue is only with missing backlight. Go to step 9.
No
No
No
No
No image displayed on LCD Replace LCD panel.
 
9. Remove glass and LCD panel screws, lift LCD panel to verify that the function cable, and LED backlight driver cable connections are secure. See Functional Overview.
Yes
Yes
Yes
Yes
If connections are OK and secure and there is still no backlight, go to step 10.
No
No
No
No
If any cable is damaged, replace affected cable and retest:
- function cable
- LED backlight driver cable (part of LCD panel)
 
10. Remove LCD panel. Set digital multimeter to DC and correct range, and verify that a 23.3–25.7 V DC voltage is present between logic board test point (24 V DC) and chassis ground (GND).
Yes
Yes
Yes
Yes
24 V DC power for backlight is present on logic board, but no backlight. Suspect no
V-sync signal coming to logic board. Go to step 11.
No
No
No
No
No 24 V DC present for LED backlight power. Replace power supply.
 
11. Replace function cable and retest. Verify that the no backlight issue is fixed.
Yes
Yes
Yes
Yes
Defective function cable prevented backlight from being enabled by logic board.
No
No
No
No
Go to step 12.
 
12. Verify if the LED backlight driver cable (part of the LCD panel) has any signs of pinched or shorted wires. Also remove the logic board and verify if one or more of the three square inductors or adjacent components on top of board show signs of overheating.
Yes
Yes
Yes
Yes
LED backlight driver cable on LCD panel found damaged. Replace LCD panel, (make
sure that you don’t pinch the LED driver cable from LCD panel) and retest. If the no backlight issue persists after LCD panel replacement, replace logic board (LED backlight output from logic board had been damaged by shorted cable.)
No
No
No
No
Suspect no LED backlight output from logic board: go to step 12.
 
13. Replace logic board and verify that the no backlight issue is fixed.
Yes
Yes
Yes
Yes
Defective logic board LED backlight driver output.
No
No
No
No
Replace LCD panel.
 
Before you go and replace anything let us know what you found. Hope this helps, good luck.

Status:

open

Edit by: oldturkey03 ,

Text:

Jason, this is not as easy as just recommending a certain part that has failed. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Just because the power /sound/etc. may be there, you can also not rule out the power supply. It may not supply the power to the LED backlight. You will need to check on that as well, taletake a good luck on the logic board. There should also be a fuse for the backlight, which may have failed. Post a couple of hi-res images of your componentslogic board with your question, so we may look at it and see if we can come up with something more concrete. HopeI would also suggest that you try the Apple Deep Dive for Blank / No Video, No Backlight:
Check Result Action Code
1. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
connectors into a known good, supported, powered-up portable. Verify display’s USB
hub and built-in camera are listed in the System Profiler’s USB device tree.
Yes
Power is available to the display logic board, and USB communication working.
Go to step 2.
No
Go to Dead Unit/No Power.
2. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspected no power to LCD panel or no DisplayPort connection with system. Go
to step 3.
3. Remove glass and LCD panel screws, slightly pivot LCD panel and verify that the internal DisplayPort cable (part of all-inone cable) and function cable are fully connected to LCD panel and logic board.
Yes
Go to step 4.
No
Reseat DisplayPort connection to LCD panel and/or function cable connections between
logic board and LCD panel and retest.
If issue persists go to step 4.
For any damaged cable, replace affected cable before testing again:
- all-in-one cable.
- function cable.
4. Unplug and replug Mini DisplayPort connector into a known-good, supported,
powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspect no power to LCD. Replace function cable and retest. If issue persists go to
step 5.
5. Replace all-in-one cable and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
LCD panel powered and detected by system. Go to step 7.
No
LCD panel still not detected by system. Suspect no LCD power from logic board.
Go to step 6.
6. Replace logic board and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
LCD panel powered and detected by system. Go to step 7.
No
LCD panel still not detected by system with replaced function cable, all-in-one cable and logic board. Suspect LCD panel video input damage.
Replace LCD panel.
7. If the Blank/No Video/No Backlight issue persists, darken room and connect to a knowngood supported system. Verify backlight is present by looking for faint glow from display.
Yes
LCD panel powered, detected by system and backlight is ON but there is no video on LCD. Replace LCD panel.
No
LCD panel is detected by system but no backlight. Check whether video is present on LCD. Go to step 8.
8. Shine bright (low heat) flashlight into the front of the LCD. and verify if any image is
being displayed.
Yes
Video is present, so issue is only with missing backlight. Go to step 9.
No
No image displayed on LCD Replace LCD panel.
9. Remove glass and LCD panel screws, lift LCD panel to verify that the function cable, and LED backlight driver cable connections are secure. See Functional Overview.
Yes
If connections are OK and secure and there is still no backlight, go to step 10.
No
If any cable is damaged, replace affected cable and retest:
- function cable
- LED backlight driver cable (part of LCD panel)
10. Remove LCD panel. Set digital multimeter to DC and correct range, and verify that a 23.3–25.7 V DC voltage is present between logic board test point (24 V DC) and chassis ground (GND).
Yes
24 V DC power for backlight is present on logic board, but no backlight. Suspect no
V-sync signal coming to logic board. Go to step 11.
No
No 24 V DC present for LED backlight power. Replace power supply.
11. Replace function cable and retest. Verify that the no backlight issue is fixed.
Yes
Defective function cable prevented backlight from being enabled by logic board.
No
Go to step 12.
12. Verify if the LED backlight driver cable (part of the LCD panel) has any signs of pinched or shorted wires. Also remove the logic board and verify if one or more of the three square inductors or adjacent components on top of board show signs of overheating.
Yes
LED backlight driver cable on LCD panel found damaged. Replace LCD panel, (make
sure that you don’t pinch the LED driver cable from LCD panel) and retest. If the no backlight issue persists after LCD panel replacement, replace logic board (LED backlight output from logic board had been damaged by shorted cable.)
No
Suspect no LED backlight output from logic board: go to step 12.
13. Replace logic board and verify that the no backlight issue is fixed.
Yes
Defective logic board LED backlight driver output.
No
Replace LCD panel.
Before you go and replace anything let us know what you found. Hope
this helps, good luck.
Jason, this is not as easy as just recommending a certain part that has failed. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Just because the power /sound/etc. may be there, you can also not rule out the power supply. It may not supply the power to the LED backlight. You will need to check on that as well, taletake a good luck on the logic board. There should also be a fuse for the backlight, which may have failed. Post a couple of hi-res images of your componentslogic board with your question, so we may look at it and see if we can come up with something more concrete. HopeI would also suggest that you try the Apple Deep Dive for Blank / No Video, No Backlight:
Check Result Action Code
1. Connect display to AC power source. Connect Mini DisplayPort, MagSafe and USB
connectors into a known good, supported, powered-up portable. Verify display’s USB
hub and built-in camera are listed in the System Profiler’s USB device tree.
Yes
Power is available to the display logic board, and USB communication working.
Go to step 2.
No
Go to Dead Unit/No Power.
2. Unplug and replug Mini DisplayPort connector into a known-good, supported, powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspected no power to LCD panel or no DisplayPort connection with system. Go
to step 3.
3. Remove glass and LCD panel screws, slightly pivot LCD panel and verify that the internal DisplayPort cable (part of all-inone cable) and function cable are fully connected to LCD panel and logic board.
Yes
Go to step 4.
No
Reseat DisplayPort connection to LCD panel and/or function cable connections between
logic board and LCD panel and retest.
If issue persists go to step 4.
For any damaged cable, replace affected cable before testing again:
- all-in-one cable.
- function cable.
4. Unplug and replug Mini DisplayPort connector into a known-good, supported,
powered-up portable system and monitor the portable’s display. Verify that the
portable’s display briefly turns off then back on.
Yes
LCD is powered and detected by system. Go to step 7.
No
Suspect no power to LCD. Replace function cable and retest. If issue persists go to
step 5.
5. Replace all-in-one cable and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
LCD panel powered and detected by system. Go to step 7.
No
LCD panel still not detected by system. Suspect no LCD power from logic board.
Go to step 6.
6. Replace logic board and reinstall LCD. Unplug and replug the Mini DisplayPort
connector into a knowngood, supported, powered-up portable system and monitor
the portable’s display. Verify that the portable’s display briefly turns off then back on.
Yes
LCD panel powered and detected by system. Go to step 7.
No
LCD panel still not detected by system with replaced function cable, all-in-one cable and logic board. Suspect LCD panel video input damage.
Replace LCD panel.
7. If the Blank/No Video/No Backlight issue persists, darken room and connect to a knowngood supported system. Verify backlight is present by looking for faint glow from display.
Yes
LCD panel powered, detected by system and backlight is ON but there is no video on LCD. Replace LCD panel.
No
LCD panel is detected by system but no backlight. Check whether video is present on LCD. Go to step 8.
8. Shine bright (low heat) flashlight into the front of the LCD. and verify if any image is
being displayed.
Yes
Video is present, so issue is only with missing backlight. Go to step 9.
No
No image displayed on LCD Replace LCD panel.
9. Remove glass and LCD panel screws, lift LCD panel to verify that the function cable, and LED backlight driver cable connections are secure. See Functional Overview.
Yes
If connections are OK and secure and there is still no backlight, go to step 10.
No
If any cable is damaged, replace affected cable and retest:
- function cable
- LED backlight driver cable (part of LCD panel)
10. Remove LCD panel. Set digital multimeter to DC and correct range, and verify that a 23.3–25.7 V DC voltage is present between logic board test point (24 V DC) and chassis ground (GND).
Yes
24 V DC power for backlight is present on logic board, but no backlight. Suspect no
V-sync signal coming to logic board. Go to step 11.
No
No 24 V DC present for LED backlight power. Replace power supply.
11. Replace function cable and retest. Verify that the no backlight issue is fixed.
Yes
Defective function cable prevented backlight from being enabled by logic board.
No
Go to step 12.
12. Verify if the LED backlight driver cable (part of the LCD panel) has any signs of pinched or shorted wires. Also remove the logic board and verify if one or more of the three square inductors or adjacent components on top of board show signs of overheating.
Yes
LED backlight driver cable on LCD panel found damaged. Replace LCD panel, (make
sure that you don’t pinch the LED driver cable from LCD panel) and retest. If the no backlight issue persists after LCD panel replacement, replace logic board (LED backlight output from logic board had been damaged by shorted cable.)
No
Suspect no LED backlight output from logic board: go to step 12.
13. Replace logic board and verify that the no backlight issue is fixed.
Yes
Defective logic board LED backlight driver output.
No
Replace LCD panel.
Before you go and replace anything let us know what you found. Hope
this helps, good luck.

Status:

open

Original post by: oldturkey03 ,

Text:

Jason, this is not as easy as just recommending a certain part that has failed. You do want to check your logic board over and see if you find any bulging or leaking capacitors. Just because the power /sound/etc. may be there, you can also not rule out the power supply. It may not supply the power to the LED backlight. You will need to check on that as well, tale a good luck on the logic board. There should also be a fuse for the backlight, which may have failed. Post a couple of hi-res images of your components with your question, so we may look at it and see if we can come up with something more concrete. Hope this helps, good luck.

Status:

open