Solution: One of the most common faults of laptop motherboard repair is a 3V or 5V power IC heating up. There could be many reasons for this dead motherboard problem. SIO (Super IO) is the controlling hub for almost all the auxillary enabling signals, such as the 3V/5V Enable signal, SUS_ON, S5 Enable, EC_ON, SUS_ON, etc.
Fig 1. 3V 5V Power IC Pinout
Step-by-step troubleshooting of 3V-5V power IC testing: -
> 3V–5V power IC input requirements like VCC, ENLDO, EN, ENC, CS#, ENTRIP1, ENTRIP2 should be available above threshold voltage.
If the above voltages are not coming at the required level, then trace back each signal one by one.
> If VCC (19 V) is not available, then the DCIN or Volt in Section requirements should be checked properly, like the switching and blocking of mosfets gate voltage triggering. Gate voltage should be available above the threshold voltage, depending on whether the mosfet is an N-channel mosfet or a P-channel mosfet.
For N-channel mosfets, the gate voltage should be greater than the source voltage by 4-6 volts, while for P-channel mosfets, the gate voltage should be less than the source voltage by 4-6 volts. If the gate terminals of both the mosfets are working fine, then there could be a fault in the mosfets or the charging IC. If the above-mentioned suspected sections are normal, then follow the next step.
> ENLDO is the enabling signal that is used to generate 3V and 5V LDOs from the standby IC. When ENLDO is not available, then the same steps must be followed. If the preceding steps are successful, the 3V/5V IC must be replaced. When ENLDO is available but the 3V or 5V IC is not working or the standby IC is heating up, follow the next step.
Fig 2. ENABLE SIGNAL OF 3V 5V IC
> The EN, ENC, CS#, ENTRIP 1, and ENTRIP 2 signals are in charge of generating PWM (pulse width modulation) voltages on 3V and 5V coils. These enabling signals are generated by the SIO or EC IC; if the 3V or 5V IC is still heating up, then there could be signal shorting or the SIO controller could be faulty.
> Check for SIO signal shorting from the basic by injecting 3V supply to it and checking for any heat up in the section, if SIO starts heating then the fault is finally in the EC controller. If EC is not heating up, then the motherboard could be analyzed by programming the EC or SIO controller using an IO programmer such as ENIT, SVOD1, SVOD2, SVOD3, or SVOD4.
If the fault status is not corrected, must inspect the output section of the 3V/5V voltage coil.
Fig 3. 3V 5V SCHEMATIC DIAGRAM.
> Using the voltage injection method from a DC power supply, the reason for the heating up of the 3V/5V standby power iC could be easily determined. By isolating the output sections one by one, the heating up of the 3V/5V IC fault could be segregated, and then troubleshooting could be done as per the findings.
The above discussed steps are important for solving 3V 5V heating problem.
For detailed information regarding the 3V 5V standby section power IC, contact us @whatsApp Dildar - +919031240767 Nasir - +919871145066 For Course.
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