Compaq Presario - wierd power problem?!

[absask]

I have a 3 yr old Compaq Presario V5000. It was left on last night (no auto hard disk off option) and I found it dead this morning.
Although there is power through AC adapter, there was no LED whatsoever.
When I tried to start there would be the Compaq logo momentarily, and then the screen goes black. If I try Ctrl+Alt+Del 3-4 times the screen comes back for a split second but with the Compaq logo with no sign of a booting process.

I am not sure why it's not booting. I tried reseating the RAM chips but that has only resulted in the power charger LED (i.e., the one with a lightning symbol) to come on steadily (as opposed to blink). Recall that this morning no LED was on with the AC source still supplying power to the laptop.

The only change lately has been a change from an aftermarket power adapter to a Compaq adapter 2 days ago. I know the new adapter is good because it has served my Armada M700 without any problem for years. The aftermarket adapter used to die on its own leaving the battery battered! Now that the laptop got a better adapter it's having this strange problem!!

PLEASE HELP!!!

 

[absask]

Forgot to add that when I try to start up-
1. the fan comes on, and
2. Likely the HD is active for a bit before both fan and HD go quiet while the blank screen takes over.

Again...PLEASE HELP!!!

 

[goombawaho]

To me, it sounds like it is running off battery power, the battery is exhausted and the laptop is not getting ac power. So, I suspect the "new" AC adapter or the DC power jack.

Is there a little battery power led/tester on the battery pack??? If so, see if it's dead. If it's dead, then I would focus on the ac adapter first.

 

[absask]

Thanks for the advice, but there is no LED tester on the battery pack
I don't think its a battery issue because the adapter works good with my other Compaq, and secondly, when I took the battery out of the one that's having problem and tried to boot by AC adapter, the exact same problem happened.
I am still looking for ideas

 

[G0AOZ]

If the BIOS logo still pops up momentarily with no battery and only the AC adaptor connected, it suggests a collapse of the dc voltage rail somewhere.

Check that the PSU is properly rated (Watts) for the Compaq, and not just right on the edge or under.

See if you can check the voltage output from the PSU under load conditions. This is easier said than done! Look at the PSU - does it have an l.e.d. on it to indicate voltage out? If this l.e.d. extinguishes or dims when you try to start the computer, this points to either the PC drawing excessive current or the PSU is unable to supply what it says it should. This is a very simple and non-scientific way to check, but there are two other options for checking PSU output under load.

Make up an extension lead with plug and socket for the low voltage output from the PSU. Now carefully connect the test prods of a voltmeter to each lead. Read off the voltage and note what happens when you try starting up the computer. Yes, on a properly working machine it will probably drop a small amount, but not appreciably.

If you haven't got the connectors for doing this, then the only other way to check would be to dismantle the laptop sufficiently for you to get the voltmeter test leads connected to the power jack socket where it connects to the motherboard.

I hesitate to suggest this last option as it is not a professional way of doing things... Take a couple of fine pins and stick one into each conductor wire (no need to go right through), now attached your voltmeter prods. Measure voltage on and off load. Keep the pins well separated along the cable so there is no accidental chance of them shorting together. By using very fine pins, you're making a very small hole in the insulation which is unlikely to allow anything else to get in and touch the conductors. This option should be marked with a skull and crossbones - use at your peril!

ROGER - G0AOZ.

 

[absask]

Thanks Roger, but seems I am closer to detecting the problem now.

So here's what I did - I connected to a second monitor and found that the laptop DID boot! This happened at work, and I am not sure what made it work here.
Anyways, on the second monitor everything seems fine. But when I disconnected it, I could only see a very dim screen, almost as if there was no backlight on the laptop monitor. However, the screen does light up normally for a split second when I close the lid and reopen, and also when I make the change from second monitor to laptop.

I looked around a bit and it seems like either of two options -
a) Screen inverter has failed
b) Backlight display bulbs (?) are fused.

I am leaning towards the first possibility, as if it were to be the other, the screen would never show up normally, even for a split second. Am I on the right track?

 

[G0AOZ]

Thanks for updating us re your problem. I'd certainly say from what you've found it's more likely to be the backlight. Remember if you're playing about with the invertor when it's running, there's around 1200 volts ready to catch the unwary...

Good luck.

ROGER - G0AOZ.

 

[goombawaho]

If it was booting/running all along, how come you didn't see the hard drive activity light or the power light illuminated??? That would have steered you and us away from a power issue.

 

[absask]

Can't explain...only when the second monitor was hooked up I saw the laptop functioning perfectly otherwise.
Question now is if its the CCFL or the inverter? I read that if its the CCFL failture, there would be a gradual deterioration of image quality - colored tint appearing on the screen etc. NOne of that sort has happened. And the screen does light up for a second when I open thje lid. Does that sound like an inverter issue then?

 

[rclarke250]

I have seen a gateway do this, appear like it is completely dead, until I removed the inverter, and hooked up an external monitor, and than it booted.