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Paul[_14_] Paul[_14_] is offline
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Default What are basic diagnostic tests on a Windows laptop that won'tboot?

Calia wrote:
On Mon, 26 May 2014 01:29:41 -0400, Paul wrote:

Try to match the table info, to your machine. Applies to
UEFI BIOS machines.

http://h10025.www1.hp.com/ewfrf/wc/d...s&dlc=en&lc=en


I get a single blink, which translates to:
LEDs blink 1 time, CPU, CPU not functional

It seems the CPU disconnects from the motherboard due to solder
cracks, at least if I understand Jeff correctly.


Not necessarily true. It could be the VCore regulator
near the CPU socket which is not functioning. It could
be a loss of power feeding into the VCore regulator (like
a problem with the circuit distributing power from battery
to elsewhere inside the computer).

CPU/Processor chips are very reliable.

On laptops with a separate GPU chip, some of those have
problems with cracked solder balls. But for the
CPU socket, it could be using a thruhole socket
with land grid array springs to make contact with
the CPU. And that doesn't have nearly the same issues
as a fine pitch BGA might.

Also, when you see LEDs blink, they may not be
blinking due to the "test procedure". They could
instead blink because of the way a power failure
is happening inside the unit. For the entries in the
table with multiple blinks, seeing the LED blink
multiple times would be a reasonably reliable
indication of a problem. But when you see one blink,
is that a "CPU test failure", or is it "the power
regulator just turned off". We don't know. Some
test results will not be that accurate and specific.
And it would be a mistake to jump to a conclusion just
yet.

I would retest with battery pack IN versus
battery pack OUT, and see if the timing of the
blink changes at all. If if was a true CPU
test failure, the timing should not change at all.
If the blink duration seems quite different,
between those two test cases, it could be an
internal power distribution issue.

Paul