No service on iPhone 6S—Try to fix iPhone Signal Part

Recently, we got an iPhone 6S need to be repaired, the issue is that the iPhone 6S says no service, it always searching signal. According our experience, we're starting with the repair signal part.

Disassemble the iPhone, remove the motherboard, and them put it under the Stereo Zoom Microscope to observe it carefully, we will know that the iPhone signal part is mainly composed of baseband CPU--U_BB_RF, baseband power U_PMU_RF, intermediate frequency U_WTR_RF, 2G antenna switch ULASM, 3G/4G antenna switch UHASM, preamplifier UDIVA_RF, 2G power amplifier U2GPA_RF, 3G power amplifier, 4G power amplifier UHBPA_RF and power supply U_QPT_RF.

Now, we are going to test iPhone, there is two cases, one is no signal at all, the other one is no signal for some SIM card.

To repair first case, no signal at all. we should make clear the baseband is starting properly, then input *#06# in the dial-up interface, if the iPhone 6s screen does not appear a string of numbers (IMEI code) which means that the baseband does not start properly, for some iPhone devices, you can see IME but if the iPhone screen does not display the IMEI after entering *#06# on the dial-up interface, it also means that the iPhone baseband CPU doesn't start normally, this is usually caused by the baseband CPU false welding, or it's also possible that baseband power is false welding, the solution is to replace new iPhone 6S CPU or baseband power parts.

If you input *#06# and see IMEI codes, it means the baseband belongs to normal start, in this case, try to install different SIM card separately, if all the SIM cards you install have no signal, the problem in the public sector, or if IC emission power supply problems, this possibility may be a bit bigger, the base band CPU or baseband power may also cause the situation. Use Titanium Alloy Tweezers to replace new parts can solve the signal problem.

To repair second case, no signal for some SIM card, for example, there is a 4G network but you can't call on the phone. It means that there is a problem in the 2G transmitting part, since the mobile 4G needs to switch to 2G when it calls, which is usually the problem of 2G power amplifier or 2G antenna switch, replace new parts can solve the problem. If there is 2G but no 4G signal, the problem is on the 4G amplifier and the iPhone 3G/4G antenna switch. Replace new parts can solve it!

At last, we repair the iPhone 6S no signal fault smoothly. By the way, we can check iPhone schematic diagram on WUXINJI Dongle, so you can fix iPhone easily.