Released September 16, 2016. Model 1660, 1778 Available as GSM or CDMA / 32, 128 or 256 GB / Rose gold, gold, silver, black, and jet black.

598 Questions View all

Working backlight but no image

I have a phone for repair it came in as no image problem with no backlight.

After checking the phone, a capacitor for the backlight, C3903, was missing. Instead of replacing it, I bridged it together which was wrong choice because it burned the backlight filter FL3901 off the trace. So after replacing the capacitor C3903 I made a jumper and connected it to C3725, enabling the backlight to turn on. Now the problem is image. I don't know where to start looking for the problem. Any response will be appreciated.

Answered! View the answer I have this problem too

Is this a good question?

Score 0
Add a comment
Mac RAM Kits
Speed up your Mac. Max out its memory.
Mac RAM Kits
Get more memory out of your Mac.

1 Answer

Chosen Solution

C3903 is a NOSTUFF component, meaning it's not placed on the logic board. It's in the schematic though and was probably used for development/testing purposes. So there is no need to replace it. The other thing is that you NEVER EVER bridge/short the contacts for a capacitor...that's not how capacitors work. So you basically forced the output of PP_LCM_BL_ANODE to ground and blew the filter FL3901. Are you certain the backlight works?

As for the LCD, this is the circuit you need to troubleshoot. Check for shorts on the outputs and then check for proper voltages.

Block Image

And check the filters...

Block Image

Was this answer helpful?

Score 2
Add a comment

Add your answer

Sarbear will be eternally grateful.
View Statistics:

Past 24 Hours: 2

Past 7 Days: 4

Past 30 Days: 26

All Time: 79