Tuesday, March 15, 2016

Apple iPhone 4S - Mother board replacement procedure – Step by step instruction to remove the mother board – Mobiles and smartphones repair and service


Category: Mobiles and Smartphones Repair and Service 

Contents of this article 

  • How to replace the Logic board 
  • Step by step instruction 





Apple iPhone 4S

Before disassembling your iPhone, be sure it is powered off.
Remove the two 3.6 mm Pentalobe P2 screws next to the dock connector.

Push the rear panel toward the top edge of the iPhone.
The panel will move about 2 mm.
Pull the rear panel away from the back of the iPhone, being careful not to damage the plastic clips attached to the rear panel.
Remove the rear panel from the iPhone.
Remove the following screws securing the battery connector to the logic board:
One 1.7 mm Phillips screw
One 1.5 mm Phillips screw.
Use a plastic opening tool to gently detach the battery connector from the socket on the device. Start lifting off the connector from the bottom side, by placing the tip of the tool between the loudspeaker enclosure and the metal cover of the connector.

The battery connector comes off vertically from the logic board. Do not apply force sideways.
Pay attention to the pressure contact underneath the top screw of the battery connector.
This may come loose while prying the battery connector from its socket.
Use a plastic opening tool to pull the pressure contact from underneath the battery connector.
When reinstalling the pressure contact, be sure to clean it with a degreaser such as windex or isopropyl alcohol. The oils on your fingers have the potential to create wireless interference.
Take notice of the position of the small black ground clip on the upper screw of the battery connector. This clip is attached only by the upper screw. When reinstalling, it must be aligned so the gold contact point will press against the back cover.
Be careful not to rip off the battery connector socket soldered on the logic board. There are 4 very small soldering points awaiting this mistake!
Insert the edge of a plastic opening tool between the battery and the outer case near the bottom of the iPhone.
Run the plastic opening tool along the right edge of the battery and pry up at several points to completely separate it from the adhesive securing it to the outer case.
Use the exposed clear plastic pull tab to peel the battery off the adhesive securing it to the iPhone.
Remove the battery.
Be careful not to pull the plastic pull tab too hard as it can be ripped off very easily.
Remove the following screws securing the dock connector cable cover to the logic board:
One 1.5 mm Phillips screw
One 1.2 mm Phillips screw
Remove the metal dock connector cable cover.
Use the edge of a plastic opening tool to pry the dock cable up from its socket on the logic board.
Peel the dock connector cable off the adhesive securing it to the logic board and the side of the speaker enclosure.
Use the edge of a plastic opening tool to pry the cellular antenna cable up from its socket on the logic board.
De-route the cellular antenna cable out from under the metal fingers attached to the logic board.
Be wary of the outer plastic ring located on top of the rear camera's flash assembly. It can be easily displaced if not removed during disassembly.
You can use tweezers, a plastic opening tool, or a spudger to remove the outer plastic ring.
Remove the following four screws securing the cable cover to the logic board:
One 2.7 mm Phillips screw
One 2.6 mm Phillips screw
One 1.3 mm Phillips screw
One 1.2 mm Phillips screw
Use the edge of a plastic opening tool to pry the cable cover tabs out of their slots cut into the EMI shield on the logic board.
Lift the cable cover from its edge nearest the top and remove it from the iPhone.
Use the edge of a plastic opening tool to pry the rear camera connector up from its socket on the logic board.
Be careful not to break any components off the surrounding area on the logic board as you pry upwards.
Remove the rear camera from the iPhone.
There is a small rubber gasket that sits underneath the rear-facing camera. Make sure that it is properly seated before reassembly.
Use a SIM card eject tool or a paperclip to eject the SIM card and its holder.
This may require a significant amount of force.
Remove the SIM card and its holder.
Remove the five cables near the top of the logic board in the following order:
Headphone jack/volume button cable
Front facing camera cable
Digitizer cable
Display data cable
Power button cable (located underneath the headphone jack/volume button cable as shown in the second picture.)
To disconnect the cables, use the edge of a plastic opening tool to gently lift their connectors up and out of the sockets on the logic board.
Be careful not to break any of the small and delicate surface mount components as you disconnect the cables.
Remove the 1.5 mm Phillips screw securing the grounding clip to the logic board near the headphone jack.
Use the tip of a spudger to pry the small grounding clip up off the logic board. Carefully grasp the grounding clip and remove it from the iPhone.
Before reassembly, be sure to clean all metal-to-metal contact points on the grounding clip (not the mating halves of connectors) with a de-greaser such as windex or isopropyl alcohol. The oils on your fingers have the potential to cause grounding issues.
Use a small flathead screwdriver to remove the 4.8 mm standoff near the headphone jack.
Use the edge of a plastic opening tool to disconnect the Wi-Fi antenna from the logic board.
If present, peel the piece of black tape covering the hidden screw near the power button.
Remove the 2.6 mm Phillips screw securing the logic board near the power button.
(Use caution when removing this screw and removing the power contact held by it; the contact tab will come loose with the screw)
Notice the small rubber bumper under the screen & digitizer cables (which are detached at top above the Q-code). This bumper can fall off of the logic board when removed or get stuck to the  cables and fall off later.
Remove the following screws securing the logic board to the case:
One 2.5 mm Phillips screw near the vibrator motor
One 2.4 mm Phillips screw
One 3.6 mm standoff along the side of the logic board nearest the battery opening.
Use a small flathead screwdriver to remove the single 3.6 mm standoffscrew.
Carefully lift the logic board from the end closest to the speaker enclosure and slide it away from the top edge of the iPhone.
Remove the logic board.
Before reassembly, be sure to clean all metal-to-metal contact points on the logic board (not the mating halves of connectors) with a de greaser such as windex or isopropyl alcohol. The oils on your fingers have the potential to cause grounding issues.
There is a small rubber bumper that sits on the top edge of the logic board where the digitizer and screen cables come through the case. It protects the cables as they bend over the top of the logic board. This can either get stuck to the cables or fall off the logic board when it comes out. Look back over step 22 for more details.
Be sure not to lose the small grounding finger for the rear facing camera near the power button. This finger rests on top of the PCB, screwed down, and covered with the adhesive black plastic tape.