Hello people, in the last course we discovered just how the iPhone X boot circuit works. Today, we are mosting likely to discover the diagnosis and upkeep of the apple iphone X boot circuit. Initially, let'' s take an appearance at the iPhone X motherboard. As we understand, the apple iphone X motherboard has two layers, the top gamer and also the layer one. The bottoms thread together and to discriminate between the leading gamer and also the bottom layer we will certainly call the leading player as a logic board and also we will call the lower layer as a signal board in future cycles the iPhone X current is more than 200mA once it'' s switched on This case is a little bit different This is not when attached to DC power This is connected to DC power After that you press the power switch or utilize the tweezers to start the phone and also the current is simply a dive from a relatively high worth and also below'' s the curve for your reference This is the apple iphone X existing contour for your reference you can see, generally the current for the boot procedure it'' s going like this beginning from about 50mA however in this The case is a lot more than 200mA So there is obviously something wrong with this boot process In this situation allow'' s see just how to do the fixing First unplug the motherboard and simply check the logic board to see suppose there is any type of present leakage If there is an existing leak after that we inspect the logic board Usage rosin check method to determine unusual locations as well as there are various situations The very first situation is that the PMU is warmed Allow'' s return to block the schema to look initially Remember this schematic layout for the boot procedure need to To work the PMU initially and after that secure some powers Outcome 15 groups of powers as well as 3 collection powers for the CPU and NAND flash chip so in this case we locate the warmth of the PMU then the issues might come from the high-voltage line produced with some brief or perhaps the PMU itself.
Inside, some circuits are shorted so first allow'' s examine the output of the PMU 17 teams of voltage by determining the diode values on the relative parts For e enough this s the result power of the PMU There are 15 teams of outcome power from the PMU to the CPU we ca check From each power rail by gauging the diet regimen values on the pertinent elements on the rail for e ample for PP_CPU_PCORE we ca gauge whether this power rail is good or otherwise by ch cking the value of the diode on this capacitor C2701 relat ve to other circuits, very same thing We can randomly select one components relevant to this rail as well as examine the diode values you discover the diode worths are normal for example here we are meas ring all 15 as well as 3 groups of power rail diode values it'' s typical t indicates the output components are ok there are no Pro lem after that, the trouble needs to be from the PMU so if it is normal the PMU can be a poor solder or harmed PMU issue so we should re-call the PMU or change the PMU with a new one and come back below if we gauge the outcome power rails unusual diode values Then we will map the abnormal rail figure out and replace the appropriate uncommon parts or chips ok allow'' s go back to right here situation 2, other chips are warming up as an example USB IC, back light IC, display IC if damaged can additionally trigger the existing boot begin of possibly even more than 200 or greater so it will certainly pick up which IC is heat then map the appropriate circuit as well as repair work by changing the chip or replacing the parts an additional case from the beginning We disconnect the motherboard and inspect the logic board simply to see if there is any kind of present leakage if it is not n there is a present leakage, so what does that mean there is no current leak on the reasoning board then the existing leak really indicates it is originating from the signal board this signal board so we have to use some rosin to the signal board then incorporate the signal board with the logic board and also put it in the iSocket outlet (suit) then use power about 20 secs after that obtain the logic board as well as the signal board and also look for components the surface area rosin thaws if you locate any elements with rosin melting this must be the problem then you will replace this chip or part so this is the fixing process for this situation and additionally we have some advice initially, Qualcomm board just Logic board is called for to start No requirement to different motherboard Intel board Both reasoning board as well as Signal board are required to begin so we need to make use of rosin check method to check logic board initially if logic board with no trouble After that we can do the disconnect and also examine the signal board often this can conserve our time since not all the fixing demand to divide 2 layers of motherboard and also one more tip for iPhone X repair service match for example iSocket is needed to refine Reliable examination In order to explain to you extra quickly we take this damaged board as an instance to show the comprehensive troubleshooting process First, make an aesthetic assessment of the motherboard The motherboard is not flawed or damaged by water and also after that link the motherboard to a DC power source We can see that There is no existing leakage from this 3 major supply rails PP_BATT_VCC ， PP_VDD_MAIN and also PP_VDD_BOOST in typical condition and afterwards get motherboard boot with tongs the boot current is more than the regular value The mistake is most likely related to the 17 power supply rails that outcome from the PMU now we We unplug the motherboard to confirm if the fault is with the upper layer or the lower layer Link the battery adapter of the top vehicle driver to the DC power supply and after that power the top layer with clamps The boot current is still higher than the typical worth So our following step is to check the 17 bars output of the PMU One at a time let'' s start with PP_CPU_PCORE First locate C2701 among the PP_CPU_PCORE test points on the bitmap and afterwards run the diode-mode dimension of this capacitor worth Scaled is typical so keep measuring the staying 16 pin test factor from the measured value I have actually shorted PP3V0_NAND so we can recognize the fault components making use of rosin discovery technique Establish the result voltage of the DC source at 3V then obtain black pin to ground as well as red pin to aim the test we can see some rosin on the surface area of this component thawed and also this is C2649 judging by this the C2649 is harmed remove the black adhesive externally first then we can just mark it with tweezers a little after that step the diode value once more this time We can see the diode worth is typical after that attach the battery port to the leading layer making use of DC power supply and obtain the leading gamer with tweezers allow'' s see the boot existing this time around this boot current is typical next thing we have to do is solder the two layers together placed both layers on the hot pad in order to solder them together after that mount the screen setting up then obtain the battery connector with this current get it with tweezers to discover out the boot present the publication current is typical and also let'' s see that the phone ya T with regular display additionally as well as system obtainable The mistake is removed so iPhone X won'' t boot with the present huge boot trouble fixed perfectly More repairing courses for apple iphone X will certainly be released in this week You can see REWA academy.rewa academy website.
tech to read more as well as with any luck REWA repair program can be beneficial to improve your ability and understanding of repair see you next course bye.
