Diagnosing Laptop Black Screen

Hi,
A friend has given me their old HP Presario which is about 7 years old. In all that time has only been turned on about 5o times in total and still is running Vista. I wanted to upgrade it a bit so my kids can use it so started with more RAM, going from 2 x 1 to 2 X 2. Unfortunately when I did the change the computer turns on but the screen remains black. I swapped back the old RAM but still the same. I have tried all different ways to test the ram, one stick at a time, different slots etc but to no avail. I put in a new Cosmos battery but apart from that I don't know what to do. When I remove all the RAM and turn on I get the four beeps telling me no RAM but when I put it back in no beeps but still no screen. Could it be all the RAM is faulty or maybe a motherboard problem. Advice would be most helpful. Thanks

 

It did have a working screen before I swapped the RAM, it always took quite a long while to come on but afterwards it seemed to be okay. I have installed windows 7. It is a V6704au model. I don't know what that equates to in the USA. We often get different models here. As you say, if it is a dodgy video chip I won't spend money on it, it cost me nothing so I will bin it. I hate to put down a computer which has hardly lived but economics rule.

 

Stick your nose right up to the screen, then shine a flashlight in there. Do you see a very faint image of the Windows desktop? If you do, the backlighting is out. Being that old, it is probably a CCFL (code cathode florescent lamp) and inverter. These typically can be replaced for less than $150 including parts, or if handy, there are many DIY tutorials on line.

Connect an external monitor and cycle through the FN + F-key options to see if the display appears on the external monitor. If it does, the notebooks graphics card is fine and it is the notebooks monitor. There's not industry standard for which F-key supports graphics output but virtually all notebooks do (for briefings and such). On my Toshiba, it is Fn + F5. Check the labels on your keys or your manual.

If you don't have an external monitor to try, most TVs support computer input.

 

I did the nose to the screen exercise using a torch and I can see life.When I rang a local laptop repairer to get a quote to fix the problem he just said said it might be the motherboard. Could this be the case?

 

Have you tried an external monitor?

 

No because I don't have the appropriate cable. That was my next move when I can get the cable, that should put the issue beyond doubt.

 

Not likely. I would call another shop. If you can see your Windows desktop using the flashlight/torch trick, then your computer is running which suggests your motherboard is just fine. Did you tell him you can see a faint image of your desktop? If so and he still suggested a motherboard right off the bat, that gives me a suspicious pause since this is one of the most common problems seen in notebooks and the torch test is probably the most widely used verification method use by professionals.

In fact, if you look up notebook backlight repairs, you will see there are sites dedicated to this. Some for DIY, some for parts, some where you send in your notebook and they fix it.

There's not much money in these type monitor repairs, but there is a lot of money in total motherboard replacements. So call another shop. As I said this is one of the most common repairs so any established laptop repair shop should be well experienced in this area. And many shops already have a flat rate established for the labor. Parts prices vary too much, due to screen size and model popularity.

Now again, this all depends on this being a CCFL and inverter backlight. LED back lighting is much more reliable and may cost a little more. But it is still most likely a monitor issue and not a motherboard issue.

Agreed. Definitely verify with an external monitor before anything else.

 

Finally connected the laptop to an external monitor and it worked fine. Thanks very much for your help, saved me some money. I am just going to use it with the external monitor as it will be used as a desktop anyway.
Plodr, you should be working for the FBI, you seem to be able to find out just about anything!!

 

Sounds like a plan. Many people also connect a full size keyboard and real mouse to complete the pseudo desktop PC conversion.

 

What really pi$$es me off is when I grab my phone, wallet and keys and get ready to head out the door then can't find my sunglasses. So I tear apart the house and find them right where I left them (but not where I should have left them) then head out the door again only to realize I don't have my keys anymore. It sucks suffering from chronic GCF (geriatric cranial flatulence).

 

I can relate to the GCF, unfortunately I can't really blame it as I have always been terribly forgetful, age has just increased it. I can remember terribly important things such as who wrote what book etc, trivialities such as where are the car keys just float out of my head. I will do as suggested as I have spare mice and keyboards and will be easier to use that way with the laptop. Thanks again.