September 2017 - Micro Soldering UK

Monthly Archive September 2017

ByMicro Soldering

iPhone 6s Plus – No Touch: SPI_AP_TO_TOUCH_CS_CONN_L

Customer fault report:

Customer attempted to open the iPhone to replace the battery. Origional screen would no longer work. Tried new screen but no longer has touch function.

Initial diagnosis

  • No water damage
  • Signs of long screw damage in Centre screwhole
  • Burnt out filter on PP_LCM_BL34_ANODE (FL4291)

In most instances of No Touch function on the 6s plus, the lines to look at are PP5V1_TOUCH_VDDH and PP1V8_TOUCH. If you have no faults on these lines the issue can be much worse. In this case the device was unrepairable.


Figure 1 is SPI_AP_TO_TOUCH_CS_CONN_L. This line is critical for touch function. If this happens to be shorted  to ground and everything else appears to look visually good. The problem will lie under the CPU.


ByMicro Soldering

iPhone 6 No Power – Case Report 329

Customer fault report:

iPhone updated on Thursday evening with the latest ios software.
The following day tried downloading a large app via cellular data. The phone started to heat up in the top right hand corner and turned itself off while the battery still had adequate charge.
iPhone will now no longer switch on.

Initial diagnosis

  • USB ammeter reading 0 then briefly to 0.5
  • No PP_VCC_Main short
  • No PP_CPU short
  • No PP3V0_NAND short
  • No PP1V8 short
  • No signs of water damage

Upon testing the backlight cicuit we have a diode reading of 0.002 on PP_LCM_BL_ANODE_CONN and the backlight caps are shorted.

stockholm U5302_RFSigns of heat coming from Stockholm (U5302_RF). Removed to find signs of oxidisation. Cleaned up replaced.

Backlight caps c1530,C1531 and C1505 all replaced with iPhone now booting with image.
Device put back together with initial screen (copy). Logic board excessively overheating with signs of screen ghosting and loss of touch functionality.

Important note: Originally thought the copied screen was causing the overheating however upon further testing this has stabilised to normal values.



After removal Meson (U2402) signs of cold solder joints are found . Chip replaced instead of reballing the original

meson Removal u2402

iPhone retested after Touch IC replacement with no more signs of ghosting or freezing.