Sony SVF15 (DA0HK9MBD0) Does Not Turned On Repair

Laptop Model : Sony SVF15

Board Number : DA0HK9MBD0

Fault : Does Not Turned On

Repair Process :

The board number was DA0HK9MBD0. It would not turn on without charging. Plug in the adapter and there will be no short circuit or trigger. Simply start with the switch and start with a bitmap.

After checking, the voltage at this point is 0. It should be 3.3V, and we start to check the source.

After checking, there is no pull-up, so it can only be caused by the EC. Since the EC is not sent, I must check the conditions of the EC, power supply, reset, LID, BATLOW, etc., and they are all normal.

It must be that the EC is broken. , it’s a pity that I couldn’t find EC to exchange for it, so I had to forget it. I went to Taobao and found out that this EC is quite cheap, NPCE985L.

Since it is cheap, it most likely does not come with a program, so I checked to see if it has read the BIOS. After checking, I found that the BIOS does not have normal power supply, so how to read the EC program?

Check his source +3V_S5.

The +3V_WAKE is transferred out through the PQ55 tube. There is +3V_WAKE, but RVCCD is not high, so the voltage of +3V_V5 does not come out. That is not easy. Continue to trace the source of RVCCD.

It turns out that this is controlled by S5_ON, and S5_ON is controlled by EC.

Measured pin 8 of EC and found that sometimes the pin has 3.3V and sometimes it is low.

During the transition, is the EC really broken? I was a little confused here, so I continued to organize my thoughts and found that +3V_S5 did not come out when EC and S5_ON were high.

 Normally, it should jump along with S5_ON to be normal. Using a bit of bit + principle, I immediately measured that there is a short wire between pin 2 of PQ20 and pin 8 of EC. I don’t care about the specific reason why it is broken and just fly the wire directly.

After further measurement, it was found that it was even more wrong. S5_ON was directly at 0, and even the jump was gone. The value was found to be 776 normal, and the flying line was no problem.

What was going on? It should be high, but why is it 0V? Look at the drawings and discover a new world.

It turns out that S5_ON is originally low when the power is not turned on, so why does it jump in the first place? Let’s start over! The test pen continued to measure the voltage on the switch.

A miracle happened. Pin 9 of CON2 actually had a voltage of 3.3V. It was triggered and the current came up normally. The repair was completed.

Conclusion:

After the Laptop is reset to EC, the working voltage of the BIOS is turned on, and then after reading the EC program, the pins are configured, and then the working voltage of the BIOS is turned off. 

If it is not read, it will continue to try to restore the working voltage of the BIOS and continue to read, so the S5_ON transition and subsequent 0V phenomenon occur.