Laptop Repair steps

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Laptop Repair steps

1 - First of all, first check whether the power adapter has voltage output. If so, then check whether the 12V, 5V, 3.3V power supply chip has a reference voltage and a standby voltage of 5V, and whether the battery charger has power supply and CPU power supply. Whether the circuit has 3.3V power supply, whether there is a reference voltage, whether the power management chip has power supply through the high and low gate drivers of the field effect transistor, according to the standby, check whether there is a fuse resistor or not, and whether there is a filter Capacitors are not broken!

2 In your case, the battery is not fully charged, but the battery is determined to be good. It is likely to be in the following situations for reference:

• The circuit terminates charging early
• The FET and boost capacitor are damaged
• The internal control parameters of the chip are damaged, so the only way is to change the chip
• If it can be discharged but not charged, the boost capacitor and FET are not damaged, and only the chip needs to be replaced. . Generally, the chip is not easy to be damaged. .
  

            3 failure to boot,
              One look, two listen, three tests.

• See if there are any obvious visible faults. If there is no place for scorching, deformation, cracking, etc. Smell the smell of burnt mush anywhere.
• Turn on the phone and listen to see if there is any normal or abnormal sound, from where it comes from.
• Detection In the absence of special tools, only a multimeter can be used to test whether the fuse resistor is blown, and whether there is an obvious short circuit. Whether the CPU and memory stick are in good contact can be tested. Be careful not to cause damage caused by artificial short-circuit when power is on.
  

     5. The display is abnormal,
From the fault, it seems that it may be a screen or screen cable problem: 1. Check whether the main board power supply and the upper screen are normal. The voltage is generally 1:00 volts, 2:00 volts, 3:00 volts.
Because the power supply of the high-voltage board of the IBM machine is the same data line as the upper LCD screen, there are several groups of 5:00 volts, about 10:00 volts, and of course 0 volts is the ground wire! Second, if there is Power supply, check the connection of the screen, and continue to measure the voltage with a multimeter. The voltage value is as above! If there is no voltage now, it must be a screen cable failure. Change a screen wire or use a wire with the same withstand voltage to pick up a screen wire. If possible, the fault can be eliminated. If the fault still exists, the screen may also be faulty. Such cases are rare and rarely exist at the same time!!! After confirming that the voltage of the screen is normal, the screen needs to be repaired. There is a micro-processing signal chip on the screen. Because there is no circuit diagram, the working voltage of each pin cannot be determined. You can only use an oscilloscope to see whether the waveform processed by this chip is correct, and go in two parts. If yes, check the surrounding capacitors. Second, if it still doesn't work, you can only replace the screen, because the pressure line of the screen is loose. Third, if there is no power supply, check whether the output voltage of the graphics card is stable. This part of the voltage is sent to a signal processing chip, and then output to the screen line. If the voltage is still normal, it can be determined that the chip is faulty. If the chip of the same type is replaced, the voltage can be output to the screen line, and then the same inspection as the second part can be performed.

6 - First, check that the motherboard is not powered on, and test whether the fifth pin of the power management chip 1632 or 1631 (mostly these two chips) has 5 volts, and whether the 21 and 22 pins have 16 volts and 5 volts. I'm looking to see if there is 2951, the 8-legged film, to see if he has 5 volts

7 - Maintenance methods for not starting the machine:
            1. Exclude power sockets, loose modules and poor contact, attachments on the motherboard, loose cpu, and virtual welding.
            2. Check whether the main power supply fuse is burnt. If it burns, the resistance value should be set. The forward direction should not be too small or the short circuit reaction can be ignored! (Exclude the isolation circuit fault and go to the next step)
            3. Measure, 3.3v/5v generation circuit/cpu main power supply circuit/battery charging circuit, with or without power supply voltage = adapter voltage, if not, repair the corresponding circuit. 3. Power start button positive terminal
If there is 3.5-5v voltage, if not, check the 3.3v/5v circuit
Generally, this circuit is generated. (The judgment of the 3.3v/5v generation circuit should be that there is no drawing. We use the reverse method to judge which circuit on the motherboard generates the 3.3v/5v circuit. First find
The chip capacitor near the memory slot is obviously (95% of the capacitors on the circuit board are used for filtering) one end is connected to the ground
The other end is connected to the output inductance of the 3.3v/5v generation circuit. There is a fuse resistor in the middle. You can also use the power supply 5v of the ps/2 mouse port to judge the 3.3v/5v generation circuit.
(Features The power supply circuits of notebooks have their own characteristics: they all have 1 inductor, 2 mos tubes (8-pin field-effect transistors) and power modules (collectively referred to as the main voltage of cpu according to different functions)
Battery charging 3.3v/5v generation circuit These three circuit structures are very similar, and the reverse method can be used to distinguish which circuit is the cpu main power supply and the chip capacitor near the cpu
There are many CPUs above p2, which generally use 3 power supplies: the main power, the core, and the outer core. It is also very simple to distinguish which is the main power filter capacitor. The largest number is the main power filter capacitor characteristics.
These capacitors are connected to the positive and negative to the negative. Which group has the largest number of capacitors in parallel and which group is the main power of the cpu. Follow the clues to find the main power generation circuit of the cpu and the battery charging circuit.
Use the positive pole of the battery to follow the 3.3v/5v generation circuit as mentioned above) Press the power button and it should generate 3.3v/5v/cpu main power and other voltages
If it doesn't, it's just a matter of guesswork, where to fix it if it's bad!
4. If the power supply is normal, it is necessary to see if the clock circuit has power supply. The 686 machine generally has 2 power supplies, 3.3v and 2.5 respectively from the 3.3v/5v generation circuit and
cpu outer core voltage generation) circuit test point Find the chip capacitor on the side.
5. The reset circuit is a headache. It is not easy to find without the chip information. Just use the reset pin of the pc card slot of the hard disk (don't tell me you don't know which one!!!) to make a simple judgment.
6. It is basically believed that the power supply and the clock reset are normal. We need to refresh the bios. For high-end notebooks, you must back up the bios. Do not avoid it.