Dell Precision M3800 won't turn on

[TopPop]

Re: Dell Precision M3800 won't turn on

Yeah, that's true but it still isn't clear for whether the board is fully working from battery. I mean, you can reach Windows and work normally with this device.

The answer tells whether this is just a symptom or the cause of your problem.

Actually, I haven't been in to Windows on this laptop. Just got in to the Dell Diagnostics. It is a pre-Windows thing.

VCC going in to PU200 is supposed to be about 19V. Also, I noticed that PR213 on the broken board looks a bit off. It's numbers on the surface are gone and the center has a light area. I measured its resistance and got 12.7K Ohms but the schematics say it should be 10 Ohms. Included is a pic of the bad resistor and a pic of a good resistor on the working board. Maybe this will help someone. The bad resistor is dropping the voltage that is going in to PU200 to 2.9V.

[Sephir0th]

Re: Dell Precision M3800 won't turn on

Maybe I was wrong all the time but from my understanding the battery wouldn't work with a bad 10 Ohms resistor at the charging controller VCC, too. Otherwise someone would have already suggested to check there. But yeah, the resistor looks odd and the internal resistance of 12.7KOhms isn't okay (10 Ohms are correct). So check for a short to GND at any side of the resistor and if nothing turns out, replace it.

[TopPop]

Re: Dell Precision M3800 won't turn on

I replaced the resistor. It split in half as I took it off the board. After replacing the resistor the board still wasn't running. It still powers on for about 4 sec and then switches off with power only from the AC adapter. The MOSFETs PQ200 and PQ201 still weren't doing their thing. I referred back to piernov's 2.1.5. Missing Voltage On The Charger IC in the stickied Laptop Battery Charging Circuit thread and I had a look at https://cdn.badcaps-static.com/pdfs/...45f6294b0e.pdf Basically, I was missing CMSRC, so no ACDRV, and found REGN was mysteriously about 0.5V. PD201 seemed OK and I suspected PC212 was partly shorted because it read about 74 Ohms. I took it off the board and rechecked it and found it was OK. The REGN pin of PU200 had a partial short to ground. So I guess now I'm replacing PU200 too.

[TopPop]

Re: Dell Precision M3800 won't turn on

I am chasing my tail. Now the board that was working is no longer working and also has the problem of switching itself off about 4 seconds after pressing the power button. Just before this started I pressed the power button, the keyboard backlight was flickering, and then after longer than 4 seconds the laptop shut off. Then the next time I tried the power button the laptop ran for only 4 seconds and shut itself off.

Also, the board I was originally working on, again, doesn't have +5VALW and +3VALW. This time PU300 isn't hot so I'm not sure what's wrong right now.