14 iPhone 7 logic board symptoms with solutions


iPhone repair

This blog will be going over 14 iPhone 7 logic board symptoms and their possible solutions. I say possibly because this blog will be going over micro soldering with the logic board. These are advanced techniques that can be used to debug your iPhone issues and it's recommended only for iPhone repair shops or people wanting to get into that business. We partnered up with www.newyorkliu.com to write this blog. Mr.Liu has been in the repair business for over 20 years with experience working in Huawei.

1. Weak WIFI signal

Wire both ends of R7704 together to fix.
iPhone7 logicboard R7704

2. White Apple Logo Loop

Replace R4710 to fix this issue.
iPhone7 logicboard R4710

3. No Power- DCPS showing 80MA

Test R2005 if it has 1.8v if it doesn't replace it.
iPhone7 logicboard R2005

4. No backlight/screen brightness

Wire both ends of FL3908 together.
iPhone7 logicboard FL3908

5. No Charge

Run a jumper on point 2 to 3 on Q4001.
dell micro tower with a monitor

6. No touch caused by water damage

1. Test FL3911 both end if it has 5.1V and if it doesn't run a wire from one end to the other. 2.Test FL3909 if it has 5.7V if it doesn't run a wire from one end to the other.
iPhone7 logicboard FL3909 FL3911

7. No Backlight or cannot adjust brightness

Usual sympton is when you connect board to DCPS and the amps jumps way too much and the board starts to heat up. First, test D3701 and D3702 using multimeter each side when reverse testing should be the same. If not the same, just replace them.
iPhone7 logicboard D3701 D3702

8. Cannot read battery or charge using i4 software

Replace R2201 to fix the issue.
iPhone7 logicboard R2201

9. Cannot open camera or not responsive due to water damage

Run a wire connecting A1 and A2 of U2501 but first test if both points give 2.95V if not run the wire.
iPhone7 logicboard U2501

10. No screen responsieness of brightness due to water damage

Test FL3908 and FL3912 if they are 5.7V if not run a wire individually from end to other.
iPhone7 logicboard FL3908 FL3912

11. No touch due to water damage

Replace FL3910 will fix the problem.
iPhone7 logicboard FL3910

12. No backlight

When testing with DCPS amps will be super jumpy. 1. Test J4502 touch Flex Connector point 35,37 and 39 will have no volt if it's bad. 2. Run a wire connecting both end of FL3901, FL3902, FL3903 individually or replace them individually to test. 3. If above testing does not solve, replace U3703 IC.
iPhone7 logicboard J4502 FL3901 FL3902 FL3903 U3703 IC

13. Screen half black and half bright

Run a wire from one end of FL3903 to the other end.
iPhone7 logicboard FL3903

14. Open camera and screen becomes dark

Run a wire from one end of FL2502 to the other end.
iPhone7 logicboard FL2502


Posted on: Aug. 13, 2018, 1:52 p.m.