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Possible defective motherboard?

Posted on 2005-04-29
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Last Modified: 2008-01-09
HP Pavilion 7950
First got this machine in March. Had been in a home that survived both hurricanes last year. (Jensen Beach, FL)
While servicing another machine, customer asked me to check this one, had boot failure and not used since they returned to home last Nov.
PC booted to a steady beep, no video.
Showed no physical damage, i.e. water, etc.
Removed all boards, memory, etc. and cleaned.
PC now booted, ran good, steady 48 hours. Ran #1 Tuff Test Pro, HD and mem OK.
Upgraded mem to 512, upgraded from ME to XP.
Had running for another 48 with no problem.
Returned to customer. Had it one day and boot problem came back.
One short beep, than steady long. Blue "HP Invent" boot screen comes up but won't go any further.
Redid all boards, PCI, Mem, DA, Same.
Replaced mem and display adapter, same.
Customer has $ invested, through me. (Upgrades based on my recommedation.)
Would like verification or any other tips before I replace mobo.
Pete
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Question by:cfourkays
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18 Comments
 
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by:Callandor
Callandor earned 200 total points
ID: 13896748
A common problem with machines experiencing repeated failures is a failing power supply in the machine, and/or the state of outlets in the owner's home.  Either one can knock a machine out for a while, have it work for a little bit, and go out again.
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by:MrAruba
ID: 13896783
try another powersupply.
and one more thing : did you use differnet keyboards?
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by:wlennon
wlennon earned 200 total points
ID: 13896789
Did water ever get into the PC??  If so, you could have a lot of troubleshooting to do.

I would first save any data you are able to, with another Hard Drive or try burning to CD-R's.  Do a Clean Install of the OS, you can do a fresh install with an XP Upgrade.

We would know more about the beep codes if you know what BIOS is in the Machine and version.

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LVL 5

Assisted Solution

by:Auriclus
Auriclus earned 200 total points
ID: 13896858
Here are the beep codes for the 7950 Pavilon's Phoneix BIOS:

http://h10025.www1.hp.com/ewfrf/wc/document?dlc=en&lc=en&product=61317&lang=en&cc=us&docname=bph07107

While I can't see anything there that matches your description of beeps, you should examine the tables yourself and see which ones matches the pattern best.  Once you find it, your troubleshooting will be much easier.

Good luck.

Auriclus
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LVL 26

Assisted Solution

by:PCBONEZ
PCBONEZ earned 200 total points
ID: 13897577
Phoenix BIOS beep codes evolved out of AMI codes..
There are over 100 Phoenix beep codes and no one seems to list all of them.
Then HP has to go customizing....

From what I can tell the one short beep is a failure in the refresh circuit to the memory modules.
(Mother board issue)

The one long beep is a memory failure. (Which makes sense if it's not getting a refresh signal.)

Either COULD be caused by a bad power supply if the MoBo isn't getting the right power.

If that doesn't do it you could 'probably' fix this thing but maybe not and it would be time consuming.

Out of practicality (desire to get it off your work bench) if swapping in a known good power supply doesn't fix it I'd replace the Mainboard..
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Author Comment

by:cfourkays
ID: 13897644
The beeps aren't in the BIOS troubleshooter. I had already looked.
It's like one normal beep followed by a continuos beep.
Fooling with it since my last post, I thought MrAruba had it.
I plugged in a different KB and it booted to the Desktop.
As I was about to post back, the beep, (tone), started, and the screen went black.
Thought it might be heat, waited, srpayed compressed air, same thing.
Now it boots to the HP intro with no beeps and than the steady beep.
Starting it without a KB gives me a double beep, normal KB error.
Almost positive It's the board.
Different PSU, same thing.
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by:cfourkays
ID: 13897669
PCBONEZ,
I must have been typing while you were posting.
Anyone have any further comments?
Y'all deserve points for helping unless someone has a more brilliant plan.
(Notice the "y'all?   Misplaced New Yorker!)
Pete
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Expert Comment

by:Callandor
ID: 13897683
Judging from what you say, I would agree that a defective motherboard would have those symptoms.  Being exposed to a hurricane can't have been good for it.
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by:
MrAruba earned 200 total points
ID: 13897727
everything execpt processor has been replaced/tested....
if possible, try another processor, if not, throw out the mobo
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Expert Comment

by:PCBONEZ
ID: 13898528
Very slim cahnce of this doing anything but considering where you are..

Try reflashing the BIOS.. Static in the storm may have buggered it up..
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by:PCBONEZ
ID: 13898532
chance
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Author Comment

by:cfourkays
ID: 13899049
Can't boot. can't flash. No chance!
Will sleep on it and probably close this tomorrow.
Poinks for everyone.
(Oops. Wrong TA.)
Thanks everyone.
Will get back!
Pete
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Expert Comment

by:PCBONEZ
ID: 13899411
I was digging around the web and I saw some interesting thing about that system.
What I found is strange but.. Mentioned way more than once so.. ????

Appearantly many HP PC's of that vintage are capped by HP's bastardized BIOS code to 128MB/slot max memory.
http://www.mcse.ms/message959096.html
http://www.pcbanter.net/showthread.php?mode=hybrid&t=643004

Specific to THAT system I saw one that stated it will support up to 1GB if the factory WinME is installed
but under XP it will only support 256Mb.
http://www.techimo.com/forum/printthread.php?t=124131
Read the post: October 17th, 2004 12:44 PM

See what happens with two 128MB sticks installed...

PCBONEZ




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by:cfourkays
ID: 13900694
Makes no diff.
Now have the thing actually booting intermittently to the XP. After a bit, the loud beep comes in and it freezes.
The board is an Asus A7V-VM which I've replaced in other machines, for other problems. Here's the specs:
http://h10025.www1.hp.com/ewfrf/wc/genericDocument?docname=bph07227&dlc=en&lc=en&cc=uk

If you read that post further, you'll notice our own "FatalException" got involved and basically said that the OS and amount of Ram, 1 G or less, shoudn't affect it.
Also, booted to my UBCD and ran memory tests, hd tests, without any failures.
Still haven't changed the CPU since I can't get the f'n thing unlatched.
I'm thinking it could be the CPU since it is an intermittant problem. Sort of.
I'm either going to get the CPU out or break it trying. AMD-K7.
Will get back.
(Still haven't given up on the mobo.)
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Expert Comment

by:PCBONEZ
ID: 13916187
With the problems comming and going like this you might want to explore bad capacitors..
A bad batch can affect any and every circuit on the board...

http://www.spectrum.ieee.org/WEBONLY/resource/feb03/ncap.html
http://cquirke.mvps.org/badcaps.htm
http://www.epinions.com/content_3906576516
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Author Comment

by:cfourkays
ID: 13916824
Went through that 2 years ago with the leaky capacitors.
IBM had a guy in this area just going around replacing the whole board in Aptivas.
Replaced about 6 myself, mostly HP, but haven't seen that in a while.
Replacement board on the way.
BTW, haven't soldered anything to a board since I built my Heathkit GR2000 color TV maybe 25 years ago.
Thanks for reminding me about those.
Pete
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Expert Comment

by:wlennon
ID: 13918506
My God...Heathkits, it's like you get a whiff of something or see something that bring you  back to a an earlier time.  I had two, AM Radio combined with an 78, 45, and 33 speed stereo record player, and an Amplifier for the above mentioned...guess that would be three! :-)

I still do soldering, but on the newer mobo's got to be careful with everything being mult-layered, you would need a low heat or cold soldering iron.  Not long ago, I had to trouble shoot (well didn't have to, but don't like inanimate objects getting the best of me) a newer motherboard, and traced it...finally down to a Diode and Resistor.  Then remembering that diodes only let electricity travel in one direction only, or I may not have found it...

Processors can withstand a lot of heat, depending on the Processor (mine is an Intel P-4 3.4 Extreme) and runs off load at 30 C full load at 36 C but can withstand heat up to 72 C and a bit more and not damage it...however a power spike can burst a component in the processor core.  Not saying this is you problem, but they are cheap enough to replace these days.  Many are cheaper than nVidia’s high end Graphics Cards.

Going back and looking at your original question, the PC ran good for 48 hours, then an unspecified period of time when taken back to the owner.  This is reminiscent of a cold solder joint, or a minute fracture in the flat copper connecting inlays, that will sometimes make a connection once enough heat causes them to expand, thus making the connect.

wlennon
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Author Comment

by:cfourkays
ID: 13920023
Also built my own Scott "High Fidelity" tuner and amplifier. Now we're showing our age.
Also, the fact that I was a Xbar telephone company technician and later supervisor helped my soldering skills.
Back to the problem, let's chalk this one up to 2 hurricanes and a PC left in a house on the beach of the Atlantic.
No salt water but I deal with salt air corrosive problems all the time. This one went a little too far.
Board's on the way and I can pick up a CPU off the Pricewatch site if needed.
Thanks, Wes
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