Today we will certainly show you an instance regarding iPhone XR keeps browsing for signal with motherboard electrical energy leakage problem Run cosmetic evaluation of the motherboard The motherboard is not deformed or water damaged Let’s construct the phone and examination Get the motherboard set up and present assembly linked Connect the battery port with the DC Power Supply Present reading on the ammeter is 116mA Judging by this, the motherboard is dripping electricity Place the SIM card Press the power button to turn on the phone The phone switches on generally Go to Setups>> General>> Concerning We can see ICCID and IMEI number here Which suggests that the SIM card can be normally reviewed Nonetheless, the phone maintains browsing for signal We can confirm since the baseband circuit is typical The fault is most likely related to the signal power amplifier circuit Disconnect the power supply Obtain the motherboard Connect the battery port with the DC Power Supply Existing reading on the ammeter is 117mA The motherboard is leaking electricity Touch the motherboard with one hand The signal power amplifier location is warm We need to take down the securing cover on the location for additional inspection Tear off the dust-proof sponge on the board Connect the motherboard to the PCB Owner Please be kept in mind that we can apply some low-temp solder paste alongside the motherboard to lower the melting factor right here Remain to stick high-temperature tape on connectors around Heat along 4 edges of the protecting cover with fast 990AD Hot Air Weapon at 400 ℃, air circulation 3 After that tear up the protecting cover with tweezers We can see that the power amplifier IC U_QET_E has burnt out Tidy U_QET_E with PCB Cleaner Continue to use some paste flux to U_QET_E Warm with QUICK 990AD Hot Air Gun at 360 ℃, air circulation 3 Take down U_QET_E from the board very carefully We can see that U_QET_E and its bonding pad have been charred Apply some medium-temp solder paste to the bonding pad Clean the bonding pad with Blowpipe at 365 ℃ After that heat with hot air gun at 360 ℃, air movement 3 Clean the bonding pad extensively with rosin soaked solder wick Clean with PCB Cleanser after that Continue to clean the burnt Pin C2 and Pin D2 on the bonding pad We discover that relevant circuits of the two pins have actually additionally been damaged Pin C2 and Pin D2 are power supply pins of PP_VDD_MAIN Because appropriate circuits of the 2 pins have been shed we need to attach the 2 pins with C1208 by jumping cords Apply some UV curable solder mask to Pin C2 and Pin D2 Solidify under the UV light for 2 mins Then maintain the surface area flat with the sculpture blade Continue to use some paste flux to C1208 Right here we require 0.02 mm Enameled Copper Cord Solder one end of the wire to C1208 with Soldering Iron at 365 ℃ After that loophole the various other end of the cable around Pin C2 and Pin D2 Continue to apply some UV treatable solder mask to the firm wire Solidify under the UV light for 2 mins After that scrape out the circuit with the sculpture blade Now we require to solder a brand-new power amplifier IC Apply some paste flux to the bonding pad Get a new power amplifier IC in the best position Solder with fast 990AD Hot Air Weapon at 360 ℃, air flow 3 Wait for the motherboard to cool for 5 minutes Clean with PCB Cleanser after that Once more, allow’s attach the battery connector with the DC Power Supply We can see that the existing analysis on the ammeter is regular this moment Currently we can assemble the phone and test Obtain the motherboard mounted and present setting up linked Connect the battery Place the SIM card Press the power switch to switch on the phone The phone activates generally Signal bars in the upper-right edge is back to typical Mistake removed Warm tips: get the phone complete assembled after confirmation of fault clearance iPhone XR Keeps Searching For Signal With Motherboard Electricity Leakage concern taken care of completely
