Diagnosing HP Desktop Computer With Windows Vists

[JoeZ430]

Hi All. I am working on a computer and wanted to get an opinion. I've got a newer HP desktop here Model a6750y. The problem was kind of weird. It started where the computer would boot but would go to a black screen shortly after booting windows. For a little while I could get in with safe mode and didn't get the black screen. The next day I booted it up and a picture came up only briefly then went black. When I power cycle the machine it's a complete black screen. I don't see any of the bios stuff flash or anything.

I started to lean towards the on board graphics chip that went bad. I had a spare card and popped it in to see if that was the problem. I had the same thing. No picture. I just bought a PSU tested from Amazon to see if it might not be supplying enough power. I'd like to get some opinions on what else it might be. Has anybody else ever experienced this? I've seen many PSU's go bad in newer Hp units which kind of made me think the power supply may be starting to go bad.

The hard drive spins up though and appears to be booting. I just can't see anything. Thanks all!

 

[kjv1611]

Few things to check:
[ul]
[li]Try running with only one stick of RAM at a time, in case one is bad. If you can get going fine with one stick, but not other(s), then that's likely the culprit.[/li]
[li]Open case, and check motherboard for leaking capacitors.[/li]
[li]Ref1:

http://www.pcstats.com/articleview.cfm?articleID=195

[/li]
[li]Ref2:

http://cquirke.mvps.org/badcaps.htm

[/li]
[li]Try Reseating everything - disconnect all wires, pull RAM, CPU, etc, then reconnect - but leave off anything not 100% necessary to boot.[/li]
[/ul]

"But thanks be to God, which giveth us the victory through our Lord Jesus Christ." 1 Corinthians 15:57

 

[FredWagner]

Joe - Try a different monitor - an HP monitor on my HP tower running Vista went bad - the backlight would come on for a bit, then go off, then not come one again until it had 'rested' for a while. Sounds similar to your symptoms.

Fred Wagner

 

[JoeZ430]

Thanks for the fast replies! I just took all the ram out and tried with one chip and didn't make a difference. I have tried 3 different monitors. 2 LCD and a CRT. I also tried using the DVI port instead of the VGA on the on board to see if the VGA went bad and that didn't make a difference. I'm about to unplug all the CD roms from the MOBO and see if that's the culprit. If not, I'm still wondering if there's not enough power feeding the components. I bought a tester and will be here in 2 days. I've never seen anything like that so it's just a hunch. Every power supply I've seen has just been bad and nothing powers on.

 

[FredWagner]

You're definitely being thorough. I had my original PSU go bad, bought a new one from HP, which was good, and hasn't given any more trouble. Try a new from HP power supply.

Fred Wagner

 

[goombawaho]

The hard drive spins up though and appears to be booting.

Do you see the hard disk drive activity light flashing for a few minutes after powering on as if it was doing a normal boot "in the dark".

Last check maybe before saying bad mobo:
Take mobo out of case and unplug everything not needed. No optical drives, no hard drive, no front usb ports, no front sound, no card reader - nothing just memory, CPU, power supply.

Put it on a non-conductive surface - tile, wood, concrete. Use the jumpers on the mobo to start it by shorting the PWR SWITCH pins with a screwdriver. Try it with built-in video and then add other video card. This eliminates a grounding to the case or other item type of problem.

 

[JoeZ430]

Ok, here's what I have done since the last time. I went and found another power supply that fit the pin out on the board. I unhooked only the main power feed and the smaller one from the old power supply and connected the other one to see if I could get a picture even from the BIOS. When I hooked the new PSU up it is doing the same thing. I unhooked everything from the mobo and booted with the same problem.

I also unhooked the HD thinking that may be the culprit and still same problem. I'll try the above and see what happens. Weird thing is, when I remove all the RAM and boot up the MOBO does error and beeps. I can also open the otical drive when this is happening. I'll check for HD light activity. I have not experienced a bad MOBO yet. This would be something if a computer this new had a bad MOBO. I appreciate all the help in this thread. This one is truly mind blowing to me.

 

[JoeZ430]

Wow! Finally got a picture. Not sure how long this will last. But it came up when I removed the CMOS battery and unplugged the machine. That was very strange. I'll report back if this truly did fix the whole entire problem. Thanks everybody.

 

[zelgar]

Strange as it may sound, but it could be a hard drive problem. I recently had a similar situation where it would hang either during or immediately after the windows screen. I ended up having to boot up with all of my HD disconnected using Ubuntu to see if there wasn't a harware problem not associated with the HD. (When I tried to boot with all of the HD still installed, Ubuntu would give errors). It was just a process of elimination to see what HD was causing the problem (fortunately it was only a data drive).

 

[kjv1611]

Yeah, sometimes clearing the CMOS by removing the battery does the trick - forgot to list that one.

But if you do have it running for a while, I'd definitely be running some hardware scans, and MAINLY be backing up any important data just in case.

"But thanks be to God, which giveth us the victory through our Lord Jesus Christ." 1 Corinthians 15:57

 

[goombawaho]

BIOS update too, if there is one. Then reset to defaults, then customize if you want to, but check all settings.