Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

[Rocky1983]

Hi everyone I was wondering if anyone could help me out with a problem motherboard? I've got 2 Dell 17R SE (7720) laptops one 3D and one non 3D. The 3D failed recently and not knowing any better I sent it to Dell and got completely ripped off for the “repair” anyways while that one was away the other decided to die on me. Whenever I plug the ac adapter in the board trips the charge and turns the light out it also doesn't turn on when the battery is connected.

I know the charger and batteries are ok as they are fine with my other machines. Rather than experience Dells horrible customer service again I was wondering if anyone could point me in the right direction with trying to find out what's going on with it. My trouble is I have no power on the board I'm hoping someone out there can advise where I should start looking. I'm trying to follow the DC in circuit but am getting abit lost.

Thanks in advance

Neil

[mcplslg123]

Re: Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

You mean your ac adapter light goes off when connected to mb?? IF so you are having short in +19v line. Check dc-in mosfets. Most likely one in the circuit has a short. THere can be further shorted components but first check dc-in fets.

[Rocky1983]

Re: Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

Hi yes that’s it the ac adapter light goes out. Thanks I’ll check out the fets when I get out of work. Thanks

[caspian]

Re: Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

is the laptop still under guarantee of Dell?
which hardware/software component of the two laptops was common that made them both fail?

[Rocky1983]

Re: Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

Hi they ran out of warranty a while ago, I tried getting an engineers report out of Dell but they were less than forthcoming. They’d told me on the phone they’d found what was wrong with the motherboard and it would cost me X amount to fix. I paid and the next day asked what the fault was. To be told “the motherboard had no power so we’ve replaced it” when it turned up they’d replaced the whole bottom of the computer ie base plate, motherboard, palm rest, keyboard and battery. They’ve given me 3 months warranty but the battery they replaced was brand new with 12 months warranty. Also the new battery isn’t recognised by the laptop but I’m taking that up with them.

All I’ve been offered is a 15% off voucher if I choose to shop with them again.

But I’m getting off topic the one they had for repair wasn’t charging the battery but still statered until it died

The one I’m working on just trips the charger as soon as it’s plugged in.

[Rocky1983]

Re: Hi can anyone help with Dell 7720 board (DA0R09MB6H3)

Looking at the schematic and a small bit of experimenting I’ve found the short is after the PQ1 mosfet but before the PU8 chip. I’m still learning how to read these properly but it’s hard going. I’m trying to find a common link between the ac in and battery as it doesn’t start on either all I can come up with so far is the ite chip which I’m hoping to remove tomorrow and se if the short goes.