HP Pavilion notes

vdub12

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Hey just a heads up.

Today I was working on an HP Pavilion 553x. The appointment was 70 miles round trip and I still have to bring the computer back tomorrow.

When I got there the system would not power up. I unplugged it opened it up and unplugged the power supply. I used my tester and it read bad. It matched the symptoms so I diagnosed it as a bad supply. I had no internet access on my phone so I could not tether my phone to my netbook so I called my wife to check on prices for me. She quoted me $80 to $90. I know I can do better but I quoted the lady 1 hour labor and the supply at $90 and told her if it was cheaper I would let her know. Its an HP so it wasn't a standard PS but i think a mico PS would work.

Now fast foreword to my lab. I put the computer on the bench and plug it in. Guess what? it powered up. Out of amazement I opened it up and hooked the power supply tester to it and it read bad again. However, I looked closer and noticed that the tester was not reading -5v. Well of course not. Its an ATX version 1.2, it does not require -5v. My power supply tester is old and I didn't pay attention to the voltages on site. I just looked at the big red light and figured it was bad do to the fact that it matched the symptoms. So I get my ohm meter and test each power lead. It was perfect. So I hook it back up and hit the power switch and nothing, no power. I hit it a few more times and nothing. So I disconnect the supply again and try a test supply. Again no power. So I sit back and start to scratch my head over this and out of no ware this thing powers up.

After some trouble shooting the power switch I come to the conclusion that this thing needs to be on AC power for at least 5 minutes before it will power up. I flash the BIOS to the latest version and still nothing until its been plugged in for at least 5 minutes. I play around in the BIOS changing some settings make sure the escd is set to clear and I disable quiet boot so I can see the post screen as well as enable on after AC power loss. I save and restart shut the system down and unplug it. I come back a few minutes later to plug it back in and nothing happens. No power. When it finally posts I notice quite boot is back on. All of a sudden I realize, BIOS battery. I pull the battery put a brand new one in and guess what. System boots every time.

I don't know about you guys but this is the first time I have seen a computer completely not power up because of a bad cmos battery. Hope this saves you guys some time in the future.

Cheers,
 
this is the first part of my diagnostics i get my multimeter and a custom made cable to check the power supply record the volatages and then check and record the cmos battery volatage.

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Batteries

I've seen so many weird things happen on old machines because of bad batteries it's one of the things I routinely check, though it's usually not that big a deal on later stuff. I've seen that business of the delayed power-on a couple of times too, but each machine only did it once and was then okay.
 
this is the first part of my diagnostics i get my multimeter and a custom made cable to check the power supply record the volatages and then check and record the cmos battery volatage.

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Thats a cool adapter.

It just so happens that I cut all the leads off a dead supply a few weeks ago. At the time I didn't know what I was saving them for. I figured i could fix a plug if I needed to. However, now I am building a test adapter.

Thanks for the tip.
 
Wow thats really clever. Nice. Think I will have to make this for myself to. :)
 
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