This is a Nitro 5 Model# AN517-52-52T3 with a no power complaint. I have 19v to first mosfet drain but 0v on source. 1.4ohm on the CPU coils. injected .9v on source of second mosfet and the CPU lights up under thermal. Does this mean the CPU is shorted to ground? I seem to remember these Nitro 5 laptops having issues with the inrush mosfets shorting out and sending charger voltage to the CPU. Thoughts?
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This has nothing to do with the DC-IN Mosfets. They're simply switching the charger voltage to the main power rail. Nothing more, nothing less. -
DC in FET's are disabled by the charging IC in the event of a short on the main power rail. It's a standard check when troubleshooting any dead laptop as it's so common.
If your main power rail impedance = CPU Vcore impedance, this is usually because of a high side MOSFET/DRMOS short in the Vcore buck converter. You can only replace the affected component to see if the CPU was damaged (which it sounds like it is). I've seen some power supplies shut off fast enough to prevent damage, but predominantly it's a damaged CPU.Comment
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Getting a high side mosfet short on gaming laptop is norm rather then exception. Every other gaming board comes with this defect and i've never seen cpu survive this shock. these days i dont even bother to replace drmos,driver ic or pwm when i see this fault -sheer waste of time and resources.Comment
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Can you explain what you would have done differently than I did, in terms of troubleshooting?Originally posted by reformatt View Post
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Your original post make the correlation between input MOSFET failure and CPU failure which was incorrect. You still arrived from A to D, but skipped B and C in between as far as troubleshooting goes. Just need to correct when needed to educate everyone on how these things work, rather than spoon feeding them with a Please Bro answer.
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