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P4P800-E deluxe: standby broken

 
 
jjmcc
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      11-08-2011, 01:52 AM

Hello folks,

I have an ASUS P4P800-E motherboard with a Pentium 4 processor, runnin
WinXP. I have been using standby on a regular basis every time I'm awa
from the computer. I've also got the power-on via realtime clock se
for 5:30 AM everyday, so the system can do it's backup. This has bee
working flawlessly for over a year. Recently standby quit workin
spontaneously: Windows says "preparing to standby" then the syste
powers down completely. Also the power-on via realtime clock doesn'
work anymore. Everything else about the system works just fine. So fa
I've tried:

1. Check all Windows and BIOS settings to make sure standby is stil
enabled.
2. Replaced the CMOS battery
3. Reset the CMOS via jumper on the motherboard
4. re-flashed the BIOS with the latest version.

It still doesn't work. Actually standby worked ONCE after the BIO
flash, but then quit again, and didn't work after a second BIOS flash.


I contacted ASUS tech support and they said it sounds like a motherboar
problem and suggested I send it in for a test. I'm not interested i
paying to have them fix it, as the motherboard is probably not worth th
cost of shipping and repair (it's long out of warranty). But I woul
like to fix it if possible. Anyone have any suggestions on where t
start? Is there any detailed hardware diagnostic software for thi
motherboard? I'm no stranger to the soldering iron, so I'm ready to hav
at it if I knew where to start.

Thanks


 
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Paul
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      11-08-2011, 07:01 PM
jjmcc wrote:
> Hello folks,
>
> I have an ASUS P4P800-E motherboard with a Pentium 4 processor, running
> WinXP. I have been using standby on a regular basis every time I'm away
> from the computer. I've also got the power-on via realtime clock set
> for 5:30 AM everyday, so the system can do it's backup. This has been
> working flawlessly for over a year. Recently standby quit working
> spontaneously: Windows says "preparing to standby" then the system
> powers down completely. Also the power-on via realtime clock doesn't
> work anymore. Everything else about the system works just fine. So far
> I've tried:
>
> 1. Check all Windows and BIOS settings to make sure standby is still
> enabled.
> 2. Replaced the CMOS battery
> 3. Reset the CMOS via jumper on the motherboard
> 4. re-flashed the BIOS with the latest version.
>
> It still doesn't work. Actually standby worked ONCE after the BIOS
> flash, but then quit again, and didn't work after a second BIOS flash.
>
>
> I contacted ASUS tech support and they said it sounds like a motherboard
> problem and suggested I send it in for a test. I'm not interested in
> paying to have them fix it, as the motherboard is probably not worth the
> cost of shipping and repair (it's long out of warranty). But I would
> like to fix it if possible. Anyone have any suggestions on where to
> start? Is there any detailed hardware diagnostic software for this
> motherboard? I'm no stranger to the soldering iron, so I'm ready to have
> at it if I knew where to start.
>
> Thanks!


A soldering iron ? I think this job needs a hot air rework station...
(That's how you remove and replace the Southbridge.)

You can get a PDF schematic from Intel, for a board of this generation.

http://www.intel.com/design/chipsets...ics/252812.htm

The problem with that schematic, is the Port Angeles might not be a
"real" chip we can get a datasheet for. So it's hard to say what
some of the logic signals from page 34 actually do, when they connect
to Port Angeles.

When the machine goes to standby, the PS_ON# signal goes to the deasserted
state, meaning 3.3V, 5V, 12V main rails are switched off. All that is left
is +5VSB. The +5VSB is regulated down, to a voltage suited to running the
Northbridge and RAM, so that the standby contents can be maintained.

When the computer comes back up later, there must be some means by which the
BIOS knows the system state. So there have to be some ICH5 status bits that
say "I was put to sleep from S3 at last power off". It might not be external
signals that you can check. You'll have to pull a copy of the ICH5/ICH5R
datasheet, and look at the docs for some of the status signals you can
see identified on page 34 of that schematic.

On page 68, you can see the PS_ON# signal coming out of Port Angeles. And
some input to Port Angeles, would be carrying a signal triggered by the
RTC timer, amongst other things.

So the problem is either ICH5 (Southbridge, BGA, hot air to remove), or
the equivalent of the Port Angeles (SuperI/O chip of some sort). On page
67, you can see the other half of Port Angeles, and it has things like
the Floppy interface, so that makes the chip type SuperI/O.

So that's roughly where you start, and I've left all the hard
work to you :-)

Paul
 
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jjmcc
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      11-11-2011, 07:52 PM

Thanks, Paul for your detailed post. I won't claim to understan
everything you said, but it gives me a good place to start understandin
what might be wrong. Actually, based on what you describe happen
normally when standby is entered, it looks to me that it's possible tha
+5VSB may be dead on my power supply, rather than it being a MB problem
That would explain why the system appears to go into standby, but the
does not wake up. Also, power supplies do tend to fail more often tha
MBs, right? I'm going to check that out right away!




 
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jjmcc
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      11-12-2011, 03:34 PM

Just thought I'd follow up for the benefit of future lurkers. It wa
after all a faulty +5VSB in the power supply. I put a voltmeter on i
and it only read 4.5 V. When I went into standby mode it dropped to 3.
V. Not good. At this point any sane person would have bought a new P
on ebay for a few bucks. But being the cheapskate that I am I took
5V, 3A wall-wart I had lying around (the MB needs 1A in standby mode)
drilled a hole in the PS, and wired it to the +5VSB line. Works like
charm! The computer now has two plugs, but who cares? So, I fixed i
with a soldering iron after all!




 
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Paul
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      11-12-2011, 11:03 PM
jjmcc wrote:
> Just thought I'd follow up for the benefit of future lurkers. It was
> after all a faulty +5VSB in the power supply. I put a voltmeter on it
> and it only read 4.5 V. When I went into standby mode it dropped to 3.3
> V. Not good. At this point any sane person would have bought a new PS
> on ebay for a few bucks. But being the cheapskate that I am I took a
> 5V, 3A wall-wart I had lying around (the MB needs 1A in standby mode),
> drilled a hole in the PS, and wired it to the +5VSB line. Works like a
> charm! The computer now has two plugs, but who cares? So, I fixed it
> with a soldering iron after all!
>
> J


Cool :-)

Paul

 
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