Home > Classifieds > Service > HOW TO REPAIR MACBOOK LAPTOPS in Shanghai


(Original works by shanghai-computer-repair.com, all rights reserved)

Apple’s design is quite accurate ,for example ,almost all the chipsets in Apple motherboards are BGA chipsets ,so you no need worry about electromagnetic interference ,it means when you use all the mac computers ,include macbook ,macbook pro ,macbook air ,imac ,mac mini ,ipad ,ipad air ,iphone ,ipod ,ipod touch ,you will never see “blue screen “problem , they are more quiet ,more stable,more faster and more colorful ,comparing with most of the normal laptops ,just like angels .


Now I will tell you how the magical machines work and how to fix them by yourself.


Normally laptops have 2 power supply sources, Ac power supply and battery power supply ,when ac power come into the motherboard ,it be separated as two ways, we analyze the first way, the first chip that be come through is the battery charger chip, when the ac power leave the battery charger chip, the voltage will be changed around 12v ,and then the 12v power will be provided to several power chips as Major power supplies ,they are cpu power chip ,cpuvtt power chip ,standby power chip ,screen backlight power chip ,Ram power chip and Northbridge power chip, now all the power chips above have Major power ,but they still can’t work ,because they still need some signals to boot the chips. Now we analyze the second way ,it comes through a diode and then go into a power chip called u6990, when leave the chip ,the voltage will be changed to 3.42V ,and then the power going through the power chip called u5010, go into the SMC called u4900 directly. The voltage is changed to a signal called SMC_RST_L, it’s the reset signal, all chips need 3 work conditions, they are power ,clock and reset . Now we continue the analyzing, when SMC get the reset signal ,it starts working, it will create a signal called SMC_PM_G2_EN, the signal going through the chip u7840 and create another signal called p3v3s5_en_l, the signal going to the Standby power chip, and then it creates the 3.3v s5 power, at the same time, the signal p3v3s5_en_l comes to the power chip called u7750, and then create the 0.9v s5 power.


Until now, all the standby powers are ready, so the macbook just wait us to press the power button.


When we pressed the power button ,a signal called pwr_button will be sent into the SMC(u4900),the signal will be changed to another signal called BTN_OUT, and change to the signal PM_PWRBTN_L immediately, the signal will be sent into the Southbridge chip to active the Chip. When Southbridge chip get the signal, it starts working ,it creates a signal called PM_SLP_S4_L to active another 3 signals: P3V3S3_EN, DDRREG_EN, P5VS3_EN_L; P5VS3_EN_L will come into the Standby power chip to create 5vs3 voltage ,the P3V3S3_EN signal will come into the MOSFET Q7910 to create 3.3v s3, at the same time ,the signal comes into the power chip u7720 to create the 1.2v Ethernet voltage , the DDRREG_EN signal comes into the RAM power chip called u7300 to create the DDR memory voltage .


Until now ,all the S3 powers are ready, and then the Southbridge chip will create S0 power.


The Southbridge chip creates the signal PM_SLP_S3_L to active signals like P1V8S0_EN, P1V5S0_EN, CPUVTTS0_EN, DDRVTT_EN, PBUSVSENSE_EN, P5VS0_EN, P3V3S0_EN to create all the S0 power. Signal SMC_ADAPTER_EN and PM_SLP_S3_L create an And gate circuit to output a signal to join with the signal AP_PWR_EN to create an Or gate circuit to create the signal PM_WLAN_EN_L, and then the wifi adapter will be active. P1V8S0_EN will come into the power chip u7760 to create the power 1.8 s0, P1V5S0_EN will come into the power chip u7710 to create the power 1.5 s0, CPUVTTS0_EN will come into the power chip u7600 to create the power 1.05v s0, DDRVTT_EN come into the power chip u7300 to create the ddr_vtt voltage, MCPCORES0_EN come into the power chip u7500 to create the mcp core voltage (the mcp is the Northbridge ,Southbridge and the video card three in one module ), P5VS0_EN will come into the MOSFET Q7940 to create the 5v S0 power, P3V3S0_EN will come into MOSFET Q7930 to create 3.3v S0, and then the 3.3v s0 power come into u7760 to create 1.8v s0 voltage, the voltage come into u7710 to create 1.5v s0 voltage, the 1.5v s0 voltage come into the power chip to create the 1.05v s0 mcp pll voltage . PP1V5_S0, PP3V3_S0, PP1V05_S0 come into the chip U7870 to create the signal S0PGOOD_RST_L, and intergrading with all the power good signals to create the signal ALL_SYS_PWRGD, the signal comes into the U4900 and then change to the signal IMVP_VR_ON_R, the signal come into the cpu vcore power chip to boot it, the chip starts working and then create two signals: PPVCORE_S0_CPU and VR_PWRGOOD_DELAY, the VR_PWRGOOD_DELAY intergrades with the signal ALL_SYS_PWRGD to create the signal MCP_PS_PWRGD, the signal comes into the mcp chip and then change to the signal CPU_PWRGD, the signal will come to CPU, so CPU will get the power good signal, the mcp starts working and output the signal LPC_RESET_L, the signal will come to the SMC u4900 and change to the signal PLT_RST* to reset all the devices, and then the chip MCP creates the signal FSB_CPURST_L, this signal comes into CPU and then give the CPU reset signal.


Until now, hard start is totally finish, and then it’s soft start ,and then loading system, you can see your familiar windows…



Leave a comment
Customer Service: (86-21) 52920164