Computer Deceased

[Thomas Thorward]

I recently moved my computer from one office location to another, and it was unplugged for several days. I hooked up the components, plugged it back in, but when I pressed the power on button, nothing happens. No fans, no lights, no signs of life whatsoever. The power light on the power supply and on the front panel are blinking at a regular .5 second interval (I don't think that was the case before when the machine was powered down) but there is no other indication of activity. The blinking continues after the power cord is disconnected, but gradualy slows and fades out. I checked the line voltage, and it is a solid 120v. The computer is a 2-year old Compaq Presario S6000NX (just one month out of warrantee - God those planned obsolescent engineers are getting good!)

I ordered a reconditioned power supply on line, since it appears that no power is getting to the motherboard, but are there other potential causes for the observed moribund condition? Any recommendations of things to try while waiting for the power supply?

[nizzy1115]

Do not be too worried, this does not mean something is wrong with your computer. Actually it is quite common that a computer wont turn on after being moved. Sometimes a part within the computer gets "unseated" and just needs to be put back in its socket. What you should do is open up the case and lay it on its side so you can work in it easier. Now, starting one at a time competly remove and put back in the ram modules, all of the power connectors from the powersupply to each component, all of the pci cards, and all of the ide cables. Now try and turn it on. If you still get nothing, it could mean that the processor came out of its socket a little, so we need to pull out the processor and put it back in. To do this (you might have to use some force) remove the heatsink from the processor and pull out the processor from its socket, and put it back in, and then replace the heatsink back down and make sure it is firmly clicked down on all sides.

I am sure one of these components (probably the ram) is not seated correctly from the move. If none of this fixes your problem, let us know and we will try some more :)

[DMR]

Given that the computer was moved, something may have become unseated or loosened in the process. If so, it may not be that power supply itself is bad, but that a connection fault is preventing the system from powering up properly. The general troubleshooting drill is this:

* Disconnect all peripheral devices (printers, USB devices, etc.) and see if removing those items has any effect on the problem.

* Open the computer's case and:
- Remove and then firmly reseat the RAM modules.
- Do the same for all PCI cards.
- Check all power and data cable connections on the motherboard and all internal devices. Make sure the cables are firmly seated into their respective connectors.
- Look for (and smell for) signs of shorted connections, heat-damaged chips, etc.
- If you have (and know how to use) a voltmeter, check the internal power cables to see if they're supplying any kind of voltage. Normal, healthy voltages you'd expect to find on the different connectors would include 12V, 5V, and 3.3V.

* If you detect no physical signs of damage and have verified that the connections/cables are OK, but the system still does not boot:

Remove/disconnect all non-critical internal components and external peripheral devices. In other words, pare the system down to: the boot drive, 1 RAM module, the video card, mouse, keyboard, and monitor. If the system boots normally with that minimal configuration, reconnect the removed components one at a time, making sure to reboot the computer after adding each individual device. Through that process of elimination, you may be able to pinpoint a particular component that, when added to the system, causes the problem to occur.

<EDIT>

Hmm, looks like nizzy1115 was faster on the draw... :)

</EDIT>

[Thomas Thorward]

Thank you for your suggestions. I tried reseating everything including th cpu, but no results. None of the power cables to components have any significant voltage, since I can't get the power supply to come on. One pin of the supply cable to the motherboard has 5v and another 4.1v but the rest measure only a few mV (23.6mV to be exact).

[DMR]

One pin of the supply cable to the motherboard has 5v and another 4.1v but the rest measure only a few mV (23.6mV to be exact).

The 5V line carries the standby voltage, which should be present whether the machine is booted or not. The 4.1V is obviously not standard/correct; did you measure that voltage under load, or not? That is, did you get that reading while the power supply cables were connected in their respective sockets, or while (all of) the power leads were disconnected?

Also- did you try booting with only the bare minimum of hardware attached/installed, and did you try the whole "process of elimination" hardware removal/replacement steps we suggested? IF not, please do so; it's about the only way you'll be able to pinpoint or rule out the problematic component.

[Thomas Thorward]

Thank you for your quick reply.

The voltage was tested with all of the components disconnected from the power supply. The 4.11 volts was on a green lead going to the mbo. The 5.0 volts was on a purple lead going to the mbo. All other leads going to the mbo, if not neutral, have varying amounts of mV, all less than 25mV. All leads to the components have voltage on the red lead that varies between 4.8 v and 5.1v in a regular pulsing pattern. The power supply is a Bestec model ATX 250-12Z.

The only component, other than the hard drive, floppy drive and CD-ROM drive, is an ethernet card. I unplugged all the drives and the ethernet card, but the power supply still won't power on.

I tested the power on button, and it is appears to be operating correctly, and there is 2.4 to 3.5 volts (it varies) going to the button from the mbo. Is there a way to get the power supply to switch on in isolation, or is a signal from the mbo needed to get it to power up? Also, is the power supply supposed to provide 12v to components, such as hard drives when it comes on?
It appears that the problem is in the power supply or the mbo. What should I try next?

[DMR]

Is there a way to get the power supply to switch on in isolation, or is a signal from the mbo needed to get it to power up?

Well- yes, and... yes. Computer power supplies usually need to be connected to a load in order to fire up, so you'll need to leave the main power connector plugged into the motherboard. However, you can "jump start" the supply by shorting the Power On pin to ground manually. By doing that, you might be able to determine if the supply is putting out any juice at all (that it is, for example, at least capable of powering the fans). Details on the procedure, with a diagram of the mobo connector pinout, can be found here.

Also, is the power supply supposed to provide 12v to components, such as hard drives when it comes on?
It appears that the problem is in the power supply or the mbo.

Yes- when functioning correctly, the supply should provide +12V, -12V, +5V, -5V, and +3.3V on the mobo connector. It should provide +12 (Yellow) and +5 (Red) on the 4-pin drive connectors.

Try "hotwiring" the supply as described in the link I posted and let us know the results.

[Thomas Thorward]

The reconditioned power supply I ordered just arrived on my doorstep, and I immediately installed it. That was the problem, definitely, as the computer is now back to normal. Strange that the power supply should decide to die coincidentally with the move to a new location, but at least a solution has been found. Thanks for your help and attention to my plight.

[DMR]

Strange that the power supply should decide to die coincidentally with the move to a new location...

Strange coincidence indeed, but computers do have a pretty twisted sense of humor some times, don't they?
Glad the new supply did the trick; beats having to replace the mobo, I guess...

[goldeagle2005]

It's possible some part of the PSU could have become dislodged when you moved the CPU