14 replies to this topic

[ynotaj]

I have a HP pavilion dv 9007 laptop and the back light is not working, I am using an external monitor on it at the moment so I know everything else is ok on it.

I have read that 3 things could be wrong, the lid closing switch, the inverter board or the fluro tube.

Is there a way of checking each item, or is it replace one and see if it works, if not replace the next item, and so on until it is fixed. Also has anyone replace these items before, I have asked two computer shops if they will fix the problem and both said no, not a laptop, too many things can go wrong when replacing the back light tube or inverter board.

I have done the easy stuff before, like add HD and cd roms and more ram to desktops, but I have never played around with laptops.

I have noticed that the screen will light up when first turned on, it has a little purple tinge to it, sometimes it will flicker then go off, sometimes it goes straight off. The screen also comes on when the lid is closed and opened up again, but only stays on for a second or two, and sometimes when you change the display resolution the screen will come on but again only for a second or two.


Thanks for any help
Tony

[RegUS_PatOff]

I don't know the answer, but do you need this ?

Maintenance and Service Guide HP Pavilion dv9000 and dv9200

[volleyball]

If the display looks ok for the few seconds or less, I'd vote inverter. If you have it up longer but is pinkish, I'd go backlighting.
The manual provided seems pretty good about showing disassembly. You can buy inverters if you are not up to the task of component replacement.
I've gotten back into monitor repair after a long absence when they became cheap enough to toss. Now with tons of lcd's out of warrenty and dieing, I find myself doing this again.
I haven't had a laptop to do yet as I haven't found one new enough to be worth it.
By the way if anyone knows of any dead desktop lcd's I'd be interested

[ynotaj]

Thanks for the info, I think I will try the inverter, it looks easier to replace, and yes the screen comes on for only a few seconds.

[diamondsol]

Sounds like the inverter, easy as to replace just follow the manual in the link shown above.

[volleyball]

Did the inverter fix your problem?

[ynotaj]

Hi Vollyball, I haven't tried it yet, I still have it plugged into a monitor. I have to take the old invertor out to see if it is a single or double type so I know what to buy.

I can't find anyone who wants to do the job for me as they say it is too hard, tried a few computer places and a couple of mates who also work for computer places, they all say no thanks. I am an electrician but am sure I can do the job ok, its just the thought of breaking it altogether that scares me, all those little plastic clips, I have the instructions thanks to the link posted, as I said it works on the monitor fine, just a real pain in the bum as you can't move it.

I will have to do something soon and when I do I will post on here what happened.

[ynotaj]

I have replaced the inverter board and still have the exact same problem.
The screen comes on when the computer is turned on, it only stays on for about 5 seconds, I have also noticed it will come on when the lid is closed and opened, but again only stays on for about 5 seconds. Another thing I have found is that when I change the resolution the screen comes on, but again only for the 5 seconds or so.

So what now, can it be the lid closing switch, is there a way of checking this without buying a new one, I don't think it is the lid switch as the screen comes on when the laptop is first powered up with the lid opened and also when the resolution is changed.

I guess there is always the possibility that the inverter I bought is faulty, but how can I check this, without having a working laptop to swap them around I can't tell.

And then there is the fluro tubes themselves, this is a dual tube screen, and as the entire screen is black it must mean both tubes went at the same time, the inverter is a dual inverter, thats why I was thinking it had to be it that was faulty.

I have not found a place that sells just the fluro tubes, they want you to buy the full screen.

I will keep you posted on what happens

[Keinokuorma]

By any chance, this isn't a quirk of APM etc???

[ynotaj]

When you say apm do you mean this ? Advanced Power Management (APM)

After I posted the results about the new inverter, I was showing my wife what was happening.

I had the external monitor plugged in to the laptop, the laptop screen was black and each time I changed the resolution the laptop would come on, but only for the 5 seconds or so, I did this about 3 times to show her, on the third attempt the screen came on and stayed on, I left it for a while and then shut down the laptop unplugged the external monitor.

When I turned the laptop back on the screen came on and stayed on, The fluro's didn't flicker but sort of rolled, the way a new 240v triphosphorous tube does as it is warming up.

I left it going for about 5 hours and no problems, I shut down and restarted, the screen stayed on for its 5 or so seconds then went off, I then tried something different, I have a function key (f5) it has a moon on it, I guess it is like a sleep button, I pressed it and the screen came on, the screen has now been on for about 4 hours, after I post this I am going to shut down and restart to see what happens.

I can't help think that it is not the fluro tubes as there are two of them, each plugging into a dual inverter, for the screen to go completely black both tubes would have to go off at the same time, and why does the screen come on everytime you start up, or when you change the resolution, I think maybe [user=10234]Keinokuorma[/user] is on to something.

I will continue to post what I find as it may help someone else out in the future.

[Keinokuorma]

[user=33457]ynotaj[/user] wrote:

When you say apm do you mean this ? Advanced Power Management (APM)

Yes.

When I turned the laptop back on the screen came on and stayed on, The fluro's didn't flicker but sort of rolled, the way a new 240v triphosphorous tube does as it is warming up.

Not entirely uncommon...

I then tried something different, I have a function key (f5) it has a moon on it, I guess it is like a sleep button, I pressed it and the screen came on, the screen has now been on for about 4 hours

Hmm, F5 itself is to refresh contents of a folder etc... or your browser window... or the desktop if that is the "active window" at the moment... depending on the laptop, it may have a FN key in blue text (often), pressed in combination with another key with blue graphs would actvate that function... this is to conserve space from the tiny keyboards where there's often no room for extra keys like on the modern desktop keyboards. Anyway, the point is that the moon sign mostly means just that, it would activate sleep mode. Although the computer should exit sleep mode upon any keyboard activity...

I can't help think that it is not the fluro tubes as there are two of them, each plugging into a dual inverter, for the screen to go completely black both tubes would have to go off at the same time

I would think so too... the tubes and inverter are probably good.

One thing is, does the inverter actually get good power? The unit is powered thru a set of chopper regulators between the battery pack and the rest of the electronics... these would work essentially as a switching power supply without a transformer in it, and regulate the voltage to the different parts, eliminating the effects of the battery voltage changes. It is this supply that switches the inverter on and off, and if it has grown weak it might explain some of the phenomena. Everytime you change the resolution, the screen calls for some off-time, and the inverter is restarted...

This could just be a nearly-blown capacitor on the board, the desktops get similar on and off problems when the mobo caps or the psu are on the fringe.

[ynotaj]

[user=10234]Keinokuorma[/user]

how can I check if the inverter is getting good power, maybe taking a volt reading while the screen is on and then another reading when or if the screen goes off again, I still have access to the inverter, but boy, it would be tricky getting a set of probes in there with out shorting across or touching anything else.

I had thought before I replaced the inverter that because it is a dual and if it had a problem it would have to be in the circuitry before it splits and divides in two and goes to the individual coils.

I am beginning to see why I couldn't get any of the small time local guys to work on this.

thanks for your help, I take it from your replies you work on these laptops.

[ynotaj]

Well I'm back on the desk top computer, I turned the laptop off last night tried it this morning and black screen again, I tried all the things that worked before, changing resolution, press Fn F5 ( which does put the computer into sleep mode, I guess it came on before when I pressed it because I then scrolled the mouse pad waking the computer up), but only got the screen to come on for that 5 or 6 seconds.

It looks like this laptop is to be forever connected to an external monitor. I will look into this further, maybe check the other end of the power lead that plugs into the inverter, it could be as [user=10234]Keinokuorma[/user]has said, poor power supply to the inverter board. And there is still the lid closing switch, it must turn power on and off to the inverter.

One thing that may come of this I that I will get to know HP dv9000 series laptops back to front .

One thing I haven't done yet is to contact HP, as I thought this was an inverter problem and out of warranty I didn't see the point, but maybe it is worth a try.

[Keinokuorma]

Have worked on some laptops, but like the newer cell phones, they can be a pain in the back to put together properly, so I don't exactly like the idea of doing much to them.

Alhtough laptops are neat for their purpose in situations requiring portability, none of them so far beat a modular desktop unit in comfort of use and servicing.

[Cobey]

Not sure if you are working this issue still, but here are some tips.

1.) Unplug your AC cord, take out the battery and press the power button for
15 or 20 sec, plug your battery and AC and check your screen. 

2.) Update to the latest system BIOS from HP (see same link as extended warranty)

3.) Check if your model is covered under the extended warranty: http://h10025.www1.h...277&lc=en&cc=us