HP Compaq dc5850 SFF Black Screen

[mitgobla]

Hi. To generalise what has been happening: I was given one of these computers for free by my school that had been said to work. I opened it up and installed some of the correct RAM (3 GB). I also checked that all the cables were correctly plugged in and they were. The problem I get is when I turn the computer on, this is what happens:

1. The green power on LED indicator turns ON
2. The green hard drive LED indicator turns ON for an extremely short duration (<0.5 sec)
3. The CPU and PSU fans come on at normal speed
4. The hard drive makes a clicking sound and spins up normally
5. It then hangs. Nothing happens, the hard drive LED stays off

The monitor does not detect a signal and turns off with the message "No Signal"

So I tested around moving components and trying the procedures said on the troubleshooting guide.

1. Removed the RAM and resat them in different orders, all correctly in with a click. No result.
2. Changed hard drive twice with two others that had an operating system on them. No result.
3. Used 3 different cables for power supply and monitor VGA. No result.
4. Tried resetting the BIOS using F10 procedure. No result.
5. Reset the CMOS. Not sure if that helped or not.

I am stuck for ideas. The computer has not been started up with any other perephials apart from a keyboard and mouse (which both work in other computers). This computer uses the default CPU which is sat properly. It does heat up and so does the PSU, but not to an alarming temperature. 

Thanks for the help.

[AtBo]

These issues can be tricky in my experience.  Just when you think you won't determine the cause, the PC will suddenly start working like it's never had a problem.

One question.  Was the PC to your knowledge working when it was given to you?  My first inclination is to reconnect the hard drive to the motherboard if you haven't done this yet.  Make sure the PC is off before you do this and make sure you ground yourself by touching metal in the case with one hand.

I have an older PC from around the same time that gave me the same problem.  I thought I was going to go crazy when it started doing this, but I basically went back and forth between unplugging the PC and reseating the hard drive connection to the PSU (also the data cable of the hard drive) until it finally started to work.  It's a funny old PC with an IDE hard drive but supports  SATA drives too.  At any rate, in a nutshell, the PC wasn't reading the hard drive.  That was the problem for me.

[mitgobla]

Hi, thanks for the fast reply.

I did remove the hard drive twice, but I will try removing it a few more times and booting it on and off. Thanks for the suggestion

[mitgobla]

No luck so farn. I even turned on the computer with the hard drive disconnected - it didn't even beep or flash to warn of a missing bootable drive! So could this mean the SATA controller has popped?

[AtBo · Accepted solution]

OK...this one you can ignore for sure:

"The monitor does not detect a signal and turns off with the message 'No Signal'"

The monitor is simply not reading a graphics signal from the motherboard, so it shuts down.  100% normal for it to do this.

Are you seeing the BIOS flash screen when the PC is first turned on?  For a normal HP, you should see the logo and then there will be instructions on which key to press to enter BIOS.

There are two connections to focus on.

1.  The PSU to the motherboard (where it connects to the motherboard).  This should be a large 20 or 24 pin connector

2.  The data cable from the hard drive to the motherboard (where it connects to the motherboard).  If this is a SATA connector it will be a small almost clip at the end of a speakerwire resembling connection wire.  If you have IDE it will be a wide flat 20 pin connector that sort of resembles the power cable where it joins the motherboard

*You might also try unconnecting and reconnecting the power to the processor.  It's I believe a 4 pin connector near the processor.  Careful with the connectors as some of them have a clip on the back side of the connection housing that you must hold in to unseat the connector.  Again, make sure the PC is unplugged and that you are grounded when there is risk you might touch the motherboard.

If you have reset these at the motherboard, you have really done all you can.  However, that doesn't mean the PC is finished or broken.

The situation I had was very similar.  Power would reach the motherboard and the hard drive and DVD ROM.  Then essentially nothing would happen.  It's so frustrating because there isn't any information to work with.  However, I made the PC sort of a project rather than just determine to fix it on the spot.  So over a month's time I would every once in awhile spend an hour or so tinkering/cleaning the inside etc.  At first the BIOS wasn't even running.  Eventually, the BIOS ran but the drive was not found.  Finally, after removing the hard drive one more time and unplugging the power cable from the PSU, I reconnected everything, and the PC booted.  For about two weeks it was on and off but then after that time of use the PC was booting every time just like normal.

You may be in this type of a situation if you want to invest the time into the PC.

[mitgobla]

Since the replied answer will take time, I have accepted it as the solution. I will try all the suggestions, and thank you for the help.
If any new problems rise I will create a new thread.

[AtBo]

mitgobla...

Just a few thoughts.  Since the PC is a little old and used, the connection housings are of the same age and probably a little bit dirty.  Older connection wires and housings can tarnish a little bit and throw things off.  I really hope you can get it running, because those old PCs are really very useful.  At least it sounds like the hardware is initializing.  That's a positive and indicates that the BIOS is reading your hardware configuration.

I do recommend just informally using a mostly dry cloth (use some pledge or endust) to gently wipe down the easily accessible parts of the case interior.  Also, take a look at the heat sink on the processor.  If it's clogged with dust see if you can gently wipe it down or blow out the dust somehow.  You might try wiping down the fans also.

I guess I might compare this situation to the situation when a car battery's connections become fouled with corrosion.  There can be other issues too, but you have looked into most of the ones that don't require having a spare part on hand.

Good luck

[mitgobla]

Hi, so I've cleaned out as much of the computer as I could access, some compressed air cans are in the post to get the deeper parts.. but something strange happened. I had tried your method of unplugging the hard drive and putting it back in a about ten times, and after I cleaned by computer and plugged it back in, it automatically came on by itself? I hadn't pressed the power button and each time I made sure the computer wasn't doing anything before I turned it off. I always turned it off via the power button and not the outlet. Could this be a sign that it is improving?

[AtBo]

It might be.  Actually, I would say it is a glimmer of light at least.

I had the EXACT same thing that you describe happen with the computer I mentioned to you.  I'm not sure, but I think it might have something to do with the initialization of the PSU and the transfer of power.  I am really guessing with this.  At any rate, at the worst of the issue, it would sometimes not do anything and then sometimes power to the fans/lights.  It's that next stage you need to get to where you see the post.  If the drive isn't read at that point, you can continue to work on things and try drives and so on.  Ultimately, I do think it's a tired (not necessarily weak) PSU or a combination of that an of tarnish on wires, cables, and connectors...too much resistance in the power channels to the parts.

When I look at this PC, I am recalling how it was actually in a cycle of sorts, like yours.  I would press the button and then green lights and fans.  Then I would press the button and nothing.  I continued unplugging the machine from the back of the PC to turn it off whether I got lights or not.  Also, I had to unplug to turn off the machine when the lights did come on, because the switch usually wouldn't work to turn it off.  That's when I started cleaning and so on and pulling the drive and reseating the motherboard side connections.  Finally, the PC posted.  I had really been worried that the mb was shot, so I was very surprised.  However, it stopped after the BIOS screen, and I realized the machine still wasn't "seeing" the hard drive.  One thing about this old PC.  It's an aftermarket build by a company called Nanosystems.  There isn't a standard BIOS screen.  There is only a header that says what the BIOS is and then on the same screen, the initialization begins.  This is what wasn't happening at this point.

I guess I was stuck here for several days, continuing to plug and unplug the PC and then reseating interior parts.  I was still convinced it was hopeless, when the PC for some reason finally saw the hard drive and booted.  I was basically ecstatic at that point and very relieved.  So it's still over in the corner in stand by.  I haven't had a boot issue since this episode.

BTW, the PC had been working for a few months (after I purchased it on ebay).  The failure didn't exactly come out of the blue, though, because, leading up to the issue, the PC had begun to post but not see the drive for about a month and a half.  I would have to restart and hope, and it always booted.  Honestly, I think I had left it off for a 3 or 4 months before the start of this, because I had moved during this time.

When it was down to nothing but the fans and power lights, I was convinced the BIOS was shot and the mb gone.  Absolutely not the case in this instance.

Recalling one thing I tried which may sound unusual.  Not sure if it made a difference, but I actually connected two drives to the computer.  I was trying to force and extra draw on the PSU to see if I could jump start it, so to speak.  I also tried using alternative connection ports for the main drive with the same purpose in mind.  Try the IDE drive and if that fails,  connect a SATA drive in the SATA 0 socket and then if a fail in the SATA 1 socket and so on.  I know this is not possible with 98%  of motherboards because they are only one or the other.  On this computer, however, while the normal main is an IDE drive, there are SATA ports.  I was able to replace the IDE with a SATA drive and try that.  This is uncommon that connections for both exist in a PC, even the older ones. 

[AtBo]

If you have a way to do so and have not already, maybe some air through the PSU would help?  Not sure about this, but I don't think it could hurt if you start running out of ideas...