Have you tried to take apart your iPhone 3G or 3GS for a cracked or broken screen and found yourself wondering what each of the numbered cables inside represent? The following article will describe each of these cable numbers and the common problems associated when each one of them is left disconnected.
The list of cables is as follows:
#1: This cable connects the glass screen/digitzer to the motherboard. Having this cable disconnected causes the touch function to malfunction on the phone. Other causes of touch function problems are a cracked iPhone screen, a defective digitizer, or the worst case is a burnt out motherboard.
#2: This cable connects the LCD to the motherboard. Having this cable disconnected will cause the LCD screen to go black. The other cause of a black/white LCD is dropping the iPhone, causing the liquid crystals to turn white upon electrification.
#3: This cable connects the ear speaker and proximity sensor to the motherboard. Having this disconnected will cause the phone to not recognize when your phone is close to your face (causing you to push buttons while talking), and/or it will cause the earpiece to not function. The small flap that secures this cable is very very fragile and turns the motherboard into a paperweight if it is broken.
#4: This cable connects the speaker, buzzer, microphone, antenna, and charge port to the motherboard. Having this disconnected will cause all of the above to malfunction. Other causes of a poor speaker output is a blown speaker.
#5: This cable connects the iPhone power button, silent/mute switch, headphone jack, and volume control to the motherboard. Having this disconnected will cause all of the above to malfunction.
#6: This cable connects the iPhone Wi-Fi antenna to the motherboard. Having this disconnected is one of the causes of a “no-wifi” message being displayed in the settings.
#7: (3GS ONLY) This cable connects the iPhone antenna to the motherboard. Having this disconnected is one reason for no cell reception. The other reason for no iPhone reception would be a poor SIM connection or a faulty SIM card.
With this guide of the above cable connections it will be much easier to troubleshoot issues when you are not certain what is going on with your phone. It will also help when disassembling your phone.