iPhone 6 No LCD - GSM-Forum

xiamurgodx · 08-08-2016, 18:57

3 days after I change screen on iPhone 6 customer comes back with no LCD. There is also no backlight either. Where do I start to diagnose which chip is bad?

cbronson · 08-08-2016, 22:30

1st, make sure the phone isn't simply in recovery mode (connect it to iTunes).

If you're sure of this, next is to see if it's a display issue or a no-power issue. When you connect it to iTunes you will know; if it's detected by iTunes then the board has power.

After that, check the voltage on C1547 and make sure it matches VCC_MAIN's expected voltage. Also check C1541, C1569, C1577, C1504 for continuity to ground and correct voltage. The first 3 (1541, 1569, 1577) should have 5.1V, the next (1504) should have 5.7V.

If C1547 has good voltage but one or more of the other capacitors does not then you have a bad Display PMU (U1501). If all of the capacitors you tested are short to ground then that also means U1501 is bad.

Let me know what you find out.

dr_goppo · 01-17-2017, 10:53

Hello,

i have a phone with no backlight (changed burnt C1552 & C1597), now have 4 volts up to connector but no 5.7 volts from u1501.

There is 4 volts on C1547, would this point to a fault with U1501 & would the missing 5.7 volts cause the backlight issue.

I can see the phone working when i shine a light on the dark screen.

Thx

Pallle · 01-17-2017, 17:37

Quote:

Originally Posted by dr_goppo

Hello,

i have a phone with no backlight (changed burnt C1552 & C1597), now have 4 volts up to connector but no 5.7 volts from u1501.

There is 4 volts on C1547, would this point to a fault with U1501 & would the missing 5.7 volts cause the backlight issue.

I can see the phone working when i shine a light on the dark screen.

Thx

Hello

Backlight problem not the U1501. It's U1502, D1501, C1505, C1530, C1531 and the corresponding filters problem.

zakvoline · 04-09-2017, 13:29

Hi, need experts help please!

Same problem here whit missing 3 lines
PN5V7_SAGE_AVDDN on C1504
PP5V7_SAGE_AVDDH - C1577
PP5V7_LCM_AVDDH - C1569
I have presend only PP5V1_GRAPE_VDDH 5.04V and PP6V0_LCM_BOOST - 6V
replaced U1501 4 times 2 new and 2 form donor boards every time same result

zakvoline · 04-09-2017, 16:31

Quote:

Originally Posted by zakvoline

Hi, need experts help please!

Same problem here whit missing 3 lines
PN5V7_SAGE_AVDDN on C1504
PP5V7_SAGE_AVDDH - C1577
PP5V7_LCM_AVDDH - C1569
I have presend only PP5V1_GRAPE_VDDH 5.04V and PP6V0_LCM_BOOST - 6V
replaced U1501 4 times 2 new and 2 form donor boards every time same result

aha lcd must be connected! if not to measure them you have to inject 1.8v form somewhere to LCM_TO_CHESTNUT_PWR_EN

gsm-raj · 04-09-2017, 18:05

sometime copy lcd makes such type of cause or two screw over lcd bar also makes such type of fault

tester2011 · 06-01-2017, 17:21

Hello, i have an iphone 6 with no display

voltage on C1547 = 4,1v
matches VCC_MAIN's expected voltage = yes
C1541 =5,04v
C1569 = 0v
C1577 = 0V
C1504 = 0V
no short to ground! could the be u1501? pleas help, thanks

Diman39 · 03-13-2018, 14:26

Quote:

Originally Posted by tester2011

Hello, i have an iphone 6 with no display

voltage on C1547 = 4,1v
matches VCC_MAIN's expected voltage = yes
C1541 =5,04v
C1569 = 0v
C1577 = 0V
C1504 = 0V
no short to ground! could the be u1501? pleas help, thanks

Have you fixed the issue? I have faced the same trouble, but I have C1569 - 4,06v not enough, must be 5,7v And of course I had changed U1501 for the working one.

ninos22 · 03-13-2018, 19:33

Quote:

Originally Posted by Diman39

Have you fixed the issue? I have faced the same trouble, but I have C1569 - 4,06v not enough, must be 5,7v And of course I had changed U1501 for the working one.

What was the original problem?

Backlight is present or not?

agrawalvikas75 · 03-21-2018, 13:18

Quote:

Originally Posted by Diman39

Have you fixed the issue? I have faced the same trouble, but I have C1569 - 4,06v not enough, must be 5,7v And of course I had changed U1501 for the working one.

i have the same problem. anyone got it fixed? need help.

ninos22 · 03-21-2018, 16:37

Quote:

Originally Posted by Diman39

Have you fixed the issue? I have faced the same trouble, but I have C1569 - 4,06v not enough, must be 5,7v And of course I had changed U1501 for the working one.

Quote:

Originally Posted by agrawalvikas75

i have the same problem. anyone got it fixed? need help.

Post all outputs of U1501 to help you and give info what cause the problem.

agrawalvikas75 · 03-22-2018, 08:13

Quote:

Originally Posted by ninos22

Post all outputs of U1501 to help you and give info what cause the problem.

supplies are ok but no voltage after turning it on.. no voltage on PP5V7_LCM_AVDDH and PN5V7_SAGE_AVDDN

ninos22 · 03-22-2018, 10:31

Quote:

Originally Posted by agrawalvikas75

supplies are ok but no voltage after turning it on.. no voltage on PP5V7_LCM_AVDDH and PN5V7_SAGE_AVDDN

Check LCM_PWR_EN and I2C rails of 1501. If there is no test points you need to remove again.

unseen · 02-12-2025, 15:33

Hello.
I have an iPhone 6S plus with no image, I'm suspecting an internal short inside the LCD assembly.
Could somebody please help me out with a quick measurement? (LCD flex connector)
I need the resistance to GND of pin 49 (PP5V7_LCM_AVDDH_CONN) on the LCD cable connector. (not the motherboard)
I don't have a replacement screen to test with, and on mine that pin is 5 Ohm to ground. I would really appreciate any help. (the 2 metallic ends of the LCD flex connector are GND)
Thank you!

08-08-2016, 18:57	#1 (permalink)
xiamurgodx Freak Poster Join Date: Dec 2005 Posts: 122 Member: 205933 Status: Offline Thanks Meter: 2	iPhone 6 No LCD 3 days after I change screen on iPhone 6 customer comes back with no LCD. There is also no backlight either. Where do I start to diagnose which chip is bad?

01-17-2017, 10:53	#3 (permalink)
dr_goppo Junior Member Join Date: Apr 2016 Posts: 2 Member: 2555986 Status: Offline Thanks Meter: 1	backlight Hello, i have a phone with no backlight (changed burnt C1552 & C1597), now have 4 volts up to connector but no 5.7 volts from u1501. There is 4 volts on C1547, would this point to a fault with U1501 & would the missing 5.7 volts cause the backlight issue. I can see the phone working when i shine a light on the dark screen. Thx

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08-08-2016, 22:30	#2 (permalink)
cbronson Junior Member Join Date: Aug 2016 Posts: 25 Member: 2608253 Status: Offline Thanks Meter: 4	1st, make sure the phone isn't simply in recovery mode (connect it to iTunes). If you're sure of this, next is to see if it's a display issue or a no-power issue. When you connect it to iTunes you will know; if it's detected by iTunes then the board has power. After that, check the voltage on C1547 and make sure it matches VCC_MAIN's expected voltage. Also check C1541, C1569, C1577, C1504 for continuity to ground and correct voltage. The first 3 (1541, 1569, 1577) should have 5.1V, the next (1504) should have 5.7V. If C1547 has good voltage but one or more of the other capacitors does not then you have a bad Display PMU (U1501). If all of the capacitors you tested are short to ground then that also means U1501 is bad. Let me know what you find out.

04-09-2017, 13:29	#5 (permalink)
zakvoline Junior Member Join Date: Apr 2015 Posts: 18 Member: 2374221 Status: Offline Thanks Meter: 1	Hi, need experts help please! Same problem here whit missing 3 lines PN5V7_SAGE_AVDDN on C1504 PP5V7_SAGE_AVDDH - C1577 PP5V7_LCM_AVDDH - C1569 I have presend only PP5V1_GRAPE_VDDH 5.04V and PP6V0_LCM_BOOST - 6V replaced U1501 4 times 2 new and 2 form donor boards every time same result

04-09-2017, 18:05	#7 (permalink)
gsm-raj Freak Poster Join Date: Jul 2014 Location: nepal Posts: 106 Member: 2226403 Status: Offline Thanks Meter: 32	sometime copy lcd makes such type of cause or two screw over lcd bar also makes such type of fault

06-01-2017, 17:21	#8 (permalink)
tester2011 Insane Poster Join Date: Mar 2011 Location: Germany Posts: 80 Member: 1528845 Status: Offline Thanks Meter: 6	Hello, i have an iphone 6 with no display voltage on C1547 = 4,1v matches VCC_MAIN's expected voltage = yes C1541 =5,04v C1569 = 0v C1577 = 0V C1504 = 0V no short to ground! could the be u1501? pleas help, thanks

02-12-2025, 15:33	#15 (permalink)
unseen Junior Member Join Date: Nov 2006 Posts: 22 Member: 383968 Status: Offline Thanks Meter: 0	Hello. I have an iPhone 6S plus with no image, I'm suspecting an internal short inside the LCD assembly. Could somebody please help me out with a quick measurement? (LCD flex connector) I need the resistance to GND of pin 49 (PP5V7_LCM_AVDDH_CONN) on the LCD cable connector. (not the motherboard) I don't have a replacement screen to test with, and on mine that pin is 5 Ohm to ground. I would really appreciate any help. (the 2 metallic ends of the LCD flex connector are GND) Thank you!