HP Pavilion PC won't post. Powers on and fans run.

I am trying to fix a HP Pavilion a630n. When power is pressed the fans run but there is no POST. I tried swapping the power supply, memory, mainboard and CPU with no success. Any input or suggestions will be greatly appreciated.
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RADONE242Asked:
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mhardy3Commented:
first step remove all non essential items such as pci cards hard drive cd or dvd till it is just your
PSU motherboard memory and processor see if it post

2nd step remove all ram see if it post an error code

3rd step remove from case and place on a nonconductive surface and attempt to fire board

4 step visually inspect capacitors and see if they are rounded or flat on the top.  
if the are rounded or bulged the board is bad.

if you get no post outside of the case with only the essentials connected then the cpu or memory or board is bad.

if it is the board it is not worth repairing

i would take the cpu and ram in a known good board and see if the work.
MarkCommented:
The only component I see that you haven't replaced is the video. Are you usig the integrated video or the pci-express slot.
MarkCommented:
Also check that the cmos clear jumper is in the right position.
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mhardy3Commented:
that is a good point sparkmaker
have you cleard the CMOS by using the jumper or removing the battery altogether?
MarkCommented:
Actually there are 2 jumpers that have to be in proper position this includes the clear bios password jumper
check this link , scroll to the middle of the page and both jumper positions and the proper procedures are here
http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&lang=en&cc=us&dlc=en&product=426322&docname=c00196251#c00196251_doc
If either of these jumpers are in the wrong position they will cause boot failure
RADONE242Author Commented:
I haven't cleared the CMOS or anything. The video is integrated. I will check for the proper jumper position.
Erik BjersPrincipal Systems AdministratorCommented:
check the power button on the case, Compaq has had some systems where the actual button would come loose and pressing the powerbutton onthe out side would do nothing.  Remove the front of the system and make sure the powerbutton is properly seated.  I spend HRS working on a system that would not power on and this was the problem.

Erik
Erik BjersPrincipal Systems AdministratorCommented:
correction: I was refering to HP systems not Compaq
RoscoeCommented:
Monitor OK? Does it work on another system? If not, the system may refuse to start unless it "sees" a working monitor...

Also, a bad keyboard/mouse can partially disable a power supply, preventing proper voltages from reaching the CPU.

Finally, I've seen HP/Compaq seemingly go brain dead when the CMOS battery has gone dead - and the only way to revive 'em is to plug in a plain old known good IDE drive (I keep an old 10GB kicking around) and the floppy, plus monitor and keyboard and boot - to at least get to the point where the initial default values (and time) can be set. After that, the optical drives etc get recognized.

Hope this helps... Ross
RADONE242Author Commented:
OK Guys,

I have resolved the issue. It turns out both the Mainboard and Power Supply were bad. I'd overlooked the power supply because it was one of the first things I tried swapping out on the old mainboard. I continued using the old power supply for all subsequent testing after swapping it out failed to resolve the problem. This is why with even the new mainboard and new CPU it still failed to post. After successfully posting with the new power supply, new mainboard, and new CPU, I tried all combinations again and determined that the CPU was fine, but the old mainboard failed in every combination. Next time I will be sure to replace the power supply with every mainboard, or thoroughly test the power supply.
MarkCommented:
GeeWhiz I was just gonna say that, but since you resolved it and none of us did, best to get your points refunded.
RoscoeCommented:
Agreed re points - and, both of them? you really had Murphy over for a visit!!!
CetusMODCommented:
PAQed with points refunded (500)

CetusMOD
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