Solved Iphone 5 Low Resolution And Blur Image In Every Lcd Iphone 5

Chosen Solution

I have a customers iPhone 5 that dropped from his hand. When I received the phone I thought it was only the LCD that need replacement, I put other LCD but still the phone has low quality image, low resolution and blur image. I replace the LCD again but still the same, I test the LCDs in other iPhone 5 and working great. I checked the FPC connector and has no damage. Can you please help me, what do you think is the problem? Is there any damage IC? Any damage resistor? Where I suppose to look? Please take a look at this photos

Update (02/21/2017) i inspected the motherboard with the microscope and i find one missing part. Please see the photos and advise me what to do

This missing part seems to be the Capacitor C440. Do you think this cause the problem? How can i fix this? Is it neccesary to find the same capacitor? Is this capacitor polarized or i can install it in any direction? Thanks for your help!!!

So you confirm that the screens do not work on this customer phone but work perfectly on a different phone? That is odd. I would double check the connector again under high magnification. Look at the soldered pins and the seating area inside. The LCD image is driven directly by the CPU so it’s not like there is an image IC to replace. You could also look at the LCM CONNECTOR page of the schematics. You will note that all of the lines are filtered by either a choke or a ferrite bead. Maybe one of them is not working properly and causing issues on the display. Using a multimeter, they should measure zero or very low (<1 Ohm) resistance. Their role is to filter out high frequency noise and they can get very resistive at high frequency. But for normal DC voltage (0 or 1), they act like a wire. It doesn’t appear to be a backlight issue but double check that too. Take a look and get back to me with more details.

This is the schematic, i marked the filters, resistors, capacitors that connected straight to the LCD connector with yellow color but i don’t know how to test them. How do i know what filter causes this problem?