iPhone 7 No Image with Backlight - GSM-Forum

squidbilly · 05-21-2018, 21:26

I am banging my head against this iPhone 7. It came to me with no image, but it would backlight. The phone is on, and detected by itunes, and my power supply shows it is running at the normal current.

The customer said it was dropped about 2 feet onto a wood floor, but the screen didn't crack, and the phone worked fine for a period after the fall. He went on to use the phone, and the screen faded out and went black.

This logic board was in near pristine condition, and everything looks good. There are no short circuits on any pins of the LCD connector.

The diode mode readings show no inconsistencies with my known good board. With the possible exception of the MIPI lines which are all about .020 volts higher. I wouldn't think that would be the problem.

So below I am posting the power lines from the connector, and their respective voltages, to see if you guys can help me out, or maybe lead me in the right direction.

PP5V7_LCM_AVDDH_CONN - 2.03v
PP5V7_MESON_AVDDH_CONN - 2.03v
PN5V7_LCM_MESON_AVDDN_CONN - 0.0v
PP1V8_LCM_CONN - 1.79v
PP1V8_TOUCH_CONN - 1.79v
PP5V1_TOUCH_VDDH_CONN - 2.04v
PP6V0_LCM_BOOST - 2.04v

This was after I replaced Chestnut with a new IC. Before I replaced Chestnut, I wasn't getting any voltage on the 5.7v lines.

I wonder if a cap could have failed and is pulling the voltage down, but this board looks immaculate. The Chestnut chip is getting main power, as is the switch for chestnut.

05-21-2018, 21:26	#1 (permalink)
squidbilly Junior Member Join Date: May 2018 Posts: 16 Member: 2835320 Status: Offline Thanks Meter: 4	iPhone 7 No Image with Backlight I am banging my head against this iPhone 7. It came to me with no image, but it would backlight. The phone is on, and detected by itunes, and my power supply shows it is running at the normal current. The customer said it was dropped about 2 feet onto a wood floor, but the screen didn't crack, and the phone worked fine for a period after the fall. He went on to use the phone, and the screen faded out and went black. This logic board was in near pristine condition, and everything looks good. There are no short circuits on any pins of the LCD connector. The diode mode readings show no inconsistencies with my known good board. With the possible exception of the MIPI lines which are all about .020 volts higher. I wouldn't think that would be the problem. So below I am posting the power lines from the connector, and their respective voltages, to see if you guys can help me out, or maybe lead me in the right direction. PP5V7_LCM_AVDDH_CONN - 2.03v PP5V7_MESON_AVDDH_CONN - 2.03v PN5V7_LCM_MESON_AVDDN_CONN - 0.0v PP1V8_LCM_CONN - 1.79v PP1V8_TOUCH_CONN - 1.79v PP5V1_TOUCH_VDDH_CONN - 2.04v PP6V0_LCM_BOOST - 2.04v This was after I replaced Chestnut with a new IC. Before I replaced Chestnut, I wasn't getting any voltage on the 5.7v lines. I wonder if a cap could have failed and is pulling the voltage down, but this board looks immaculate. The Chestnut chip is getting main power, as is the switch for chestnut.