Sony VGN-CR323 no power

[lohliak]

Dear all, I have a big problem here. I have a sony VGN-CR323 laptop with problem can't power on. It won't even charge the battery and when I measure with DMM only the mosfet pointed with red arrow have 19V and the other side is 0V. after I unplug the adapter, the cap connected to the mosfet still holds a voltage and drop slowly. Any ideas from the expert here or any hint provide to help me check? Thanks in advance.

[mattbrad2]

Re: Sony VGN-CR323 no power

Is the mosfet on top of it shorted? These 2 fets are part of a buck controller circuit. Your problem could be in the maxim IC that sits to the left. Your not getting 19v to the other side because the other side is grounded out. This could be a bad fet somewhere else on the board, bad ceramic cap or a shorted PWM controller. In your case.. that Maxim 8632e IC. If you had the proper equipment, you could temporarily remove it and re-test.

[lohliak]

Re: Sony VGN-CR323 no power

Dear mattbrad2, I use DMM to measure the FET's 2 side and it seems not short. I tried to measure 8632e VCC and it's 0V. I've downloaded the schematic and I found that VCC3 is not present. I'm out of idea.

[mattbrad2]

Re: Sony VGN-CR323 no power

How are you measuring those mosfets? If either side is shorted to ground, you'll need to lift one side and measure the FET out of circuit. With one side lifted, set your DMM to diode and measure one of the middle pins to one of the middle pins on the opposite side. Flip the probes around and measure again. You should see infinity in one direction.

[red_raian]

Re: Sony VGN-CR323 no power

shorted southbridge problem of sony laptop hard fix..

[lohliak]

Re: Sony VGN-CR323 no power

Dear all, I started to suspect the small board with DC Jack is giving problem. I don't have schematics for the board with p/n DAGD1ABB8B0. I saw there's a MAX1908E on it. I measured DCIN=19V, LDO=5.38V REF=4.08 VCTL=5.38, BATT=0, CSIP=0, CSIN=0, DHI=0, DLVO=5, DLO=0. Any hints??? Would it be MAX1908e that caused the problem?