HP 820 G1 (6050A2630701-MB-A01) Does Not Power On Repair

Laptop Model: HP EliteBook 820 G1 

Motherboard Number: 6050A2630701-MB-A01

Fault : Does Not Power On

　　

Repair Process:

 

Measure 3V, 5V, 1.35V, 1.05V are normal, and the CPU power supply is not. After connecting the memory value card, the measurement found that the VTT voltage was only 0.6V, which was abnormal.

 Later, it was found that the VTT voltage was 0 when the load (memory) was connected. The memory power supply chip is TPS51362, which is generally used for 1.05V power supply. I downloaded a data sheet and found that this chip is a 0.6V-2V adjustable output power supply chip.

It divides the voltage through two peripheral resistors and REF on pin 25 to output the required voltage. For example, if 1.35 is output here, the PWM output is 1.35,

So remember to check the Target output voltage input pin here after repairing the chip. 0.6 V to 2 V, 1.05 V/1.2 V built-in (GND and Open) (see Table 1), target output voltage input pin, 0.6V to 2V, 1.05V/1.2 V built-in (GND and Open) (see Table 1).

However, this chip does not output VTT power supply, so the memory power supply circuit using this chip requires an external power supply chip to provide VTT.

After careful observation of the motherboard, I found that the silk screen of U6240 is Q23Z G2997B, and I found the data sheet of this small chip.

1. Pin 2 is 1.35V normal, pin 3/5 is 0.6V, pin 6 VTTREF is normal 0.68V, pin 7 S3 is 0V, pin 9 S5 is 3.89V, and pin 10 is 3.3V normal. 0V on pin 7 means that the chip is not working. No wonder the VTT output is only 0.6. This is a false voltage, so it is directly 0 after adding a load.

　　Let’s not mention the 0V of S3 for now. The normal value of S5 should be 3.3. Why is it so high? Something is wrong. If there is no drawing, then I will look for the EC drawing first, and then I found this HP EliteBook 820 G1 strange fault repair  (Source: google.com)

　　Exactly the same phenomenon, exactly the same problem, the SLP was too high, so I decisively purchased it at 0.5, and then found U2511 based on the post. I didn’t even notice the obvious burnout.

Remove U2511, the standby current is 0.005, but it does not trigger. Replace it with the original cable.

Connect the original cable and the standby current is 0.007. Press the switch and the current will run all the way and the phone will turn on.

I looked at the USB interface and found that part of it was damaged. Fortunately, there was a chip conversion, otherwise I might have directly burned the CPU.

 

Happy Repairing !!