The boot circuit maintenance skill is a process from theory to practice, gradually exploring the accumulation of experience, so in the process of learning, we must firmly master the basic concepts, composition structure and working principle of the motherboard power-on circuit, and constantly accumulate the fault analysis of the boot circuit. Therefore, it will eventually master the maintenance skills of this circuit.
The power-on power circuit of the motherboard is the basis of the normal start and operation of the motherboard. Once the problem occurs, the motherboard cannot be turned on.
The electronic components and hardware devices constituting the power-on circuit are relatively dispersed on the motherboard, but the electronic components and hardware devices can be easily identified according to circuit diagrams or gradually accumulating experience.
The following is listed below to analyze the principle of power-on power-on power-on circuit power boards, multi-angle explanation of the working principle and key points of the main board.
Excessive study of elite motherboard boot circuit
The elite P67H2-A motherboard uses Intel's P67 chipset, which is a single chip design.
As shown in Figures 4-15, the logical relationship between the main signal during the main signal of the elite P67H2-A motherboard, 1, 2, 3, 4, 5, 6 in the figure, indicate that each major signal and power is opened during the main board. Successful order. These booting actions are explained below, further deepening the understanding of the working principle of the main board power-on circuit.
1. Step 1: + PS_3VSB
After the ATX power supply in the computer host 220V, the MMS ATX power socket starts output 5VSB standby power supply.
Figure 4-15 Box of Main Signal Logic during the boot
The 5VSB standby power supply output from the motherboard ATX power socket has passed a three-end adjustable actuer APL1086 and its peripheral resistor and capacitor, and outputs 3VSB standby power supply, providing a chip or related circuitry that requires this voltage, including I / O Chip. A circuit diagram of 3VSB standby power is converted to 5VSB standby power supply as shown in Figures 4-16.
Figure 4-16
Figure 4-165VSB standby power converts 3VSB standby power circuit diagram
2. Step 2: RSMRST_L
This signal is a signal supplied to the PCH chip for the I / O chip for resetting the PCH chip sleep wake-up logic. When this signal is abnormal, the PCH chip will not be able to operate normally, causing the system that cannot be started normally. As shown in Figure 4-17, a schematic diagram of the PCH chip RSMRST_L signal input circuit.
Figure 4-17
Figure 4-17PCH chip RSMRST_L signal input circuit diagram
3. Step 3: fp_pwrbtn_l
When the user presses the power switch on the host chassis, the front-end control panel pin of the motherboard issues a power-on signal to the I / O chip, which is a hop signal to notify the I / O chip to boot start operation. As shown in Figures 4-18, the front end control panel pin circuit diagram of the motherboard is known from the figure, and its pip is used to deliver the FP_PWRBTN_L signal.
Figure 4-18
Figure 4-18 Motherboard front end control panel pin circuit diagram
4. Step 4: SiO_PWRBTN_L
When the I / O chip is working properly, and after receiving the boot signal transmitted by the front-end control panel pin, a PWRBTN # boot signal of the PCH chip will detect a power-on signal to make the PCH chip operate.
As shown in Figure 4-19, it is a circuit diagram of the main signals such as RSMRST_L, FP_PWRBTN_L, SIO_PWRBTN_L, SLP3_L, PSON_L, and the like during power-on.
Figure 4-19
Figure 4-19 Electrical simplification of the main signals in the power-on I / O chip in the boot process
5. Step 5: SLP3_L
The PCH chip can work normally, and after receiving the power-on signal transmitted by the I / O chip, the SLP_S3 # and other pins sequentially issued a control signal, so that the system will step by step. Where the SLP_S3 # signal pin delivery signal gives the I / O chip. As shown in Figure 4-20, it is a connection circuit diagram of signals and pins such as PCH chip PWRBTN #, SLP_S3 #.
Figure 4-20
Figure 4-20PCH chip PWRBTN #, SLP_S3 # Connection circuit diagram of signals and pins
6. Step 6: PSON_L
After receiving the power-on confirmation signal of the PCH chip, the I / O chip will send a PSON_L signal to the first pin of the motherboard ATX power outlet. The motherboard ATX power outlet begins to output 3.3V, + 5V, and -12V, + 12V supply of various specifications to provide various chips, circuits, and hardware devices on the motherboard. The circuit diagram and a physical map of the ATX power socket of the motherboard are shown in Figures 4-21.
Figure 4-21
Figure 4-21 Circuit diagram and physical map of the motherboard ATX power socket
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