Dell D820 Win 7 Crashes before password entry

April 21, 2013 at 13:59:05
Specs: Windows 7, 1.66 dual core
With much finagling and an external keyboard I can enter the system setup and it also crashes when windows starts up on a known working install USB, just before you get the language selection screen, so I haven't been able to run the repair utility.

I had a bad battery but just replaced it with a factory new replacement, and it shows full charge, although the power adapter doesn't light up with the green led anymore...but that should be beside the fact since I have a fully charged battery, right?

I read something about a common problem with a solder problem causing video crashes with widows 7, but wouldn't that leave the system running with a blank screen? Mine immediately starts to power up again.

The hard drive bad? I'm stuck.


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#1
April 21, 2013 at 14:08:25
A desoldered GPU typically results in the laptop failing its POST test, so it never actually boots. You know this happened to your HP laptop when the Caps Lock light blinks 4 times, and nothing else happens.

If I had to guess (and I am), I'd check to make sure the fan(s) are working as intended, the heatsinks are clear of dust, and the power supply (and its cables) are good. If so, I'd check the voltage regulator.

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#2
April 21, 2013 at 17:52:20
Thanks for the considered reply. Thinking back to before the system failed to initialize, I do remember the system getting very hot.

I will bite the bullet and open it up and check the coils and ICs of the voltage regulation system. Thanks for the reply.

Peter


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#3
April 21, 2013 at 19:12:40
Well, the good news is if you get far enough into the laptop to look at the MB, you're already 80% of the way there towards solder reflowing. The next 15% is getting an oven you'll never use for food again.

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#4
April 27, 2013 at 01:45:25
Quite frankly, Other than reading lately about "reflow" I've never heard the term. I've been out of bench tech work since the 486 days. I imagine I'll just give it up.

But I am curious, none the less as to what you mean. Do you use an oven to burn off excessive flux, etc and "reflow" the connections of an entire board? How novel. Perhaps paying time in a local ceramic kiln would be more logical as such vapors would not be ruinous to a kiln.

Peter


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#5
April 27, 2013 at 08:18:20
On modern laptop designs, the GPU pins are directly below the chip, like a CPU. Unlike the CPU, these chips are soldered on the board. The question becomes, how do you get a solder iron between the chip and board to melt the solder and bind the chip? The answer is you don't. You heat the entire thing to the melting point of solder.

I'm told factories use an oven to do this. Professional repair shops use a solder reflow station. Reflow stations are basically a hot plate with a heat lamp so you only melt solder on the one bit you care about. They cost more than a new laptop, so get one only if you're in the business of fixing laptops. But I can get a toaster oven at Walmart for $40, and it'll reach the required temperatures (though just barely). To protect the rest of the board, you cover the bits you're not fixing in aluminum foil. A toaster oven has more risks than a reflow station, but your laptop's ready broke, so what's the harm in breaking it more?

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