Trying to fix a SONY PCG-7F1L laptop, need help diagnosing the issue

[DaMaN]

Hey all, I am trying to fix a SONY PCG-7F1L laptop that has a weird problem.

It powers on but the laptop LCD screen display keeps shutting off when the screen is opened wide enough for normal use. If I barely crack it open enough to turn the power button on it will come on and display the boot screen and load into the windows xp desktop normally but as soon as I open the screen more than 15 degrees it will shut off the screen output completely.

When I have it running and cracked open to bare visibility for a sustained amount at a time (15 minutes) then open it all the way to a normal ~90degree viewing angle the screen blanks out but i still see faint remnants of what was open on the screen before doing so and can see the start menu popping up and down while I toggle the windows key on the keyboard for about 15 seconds then it all fades away.

Any ideas of what the problem could be? I am thinking a bad inverter cable that goes through the hinges that needs to be replaced but wanted to bounce it off you guys to get some other perspective.

I event tried to toggle the panel>> power settings to "do nothing" when the lid is closed to no avail.

What else should I be looking for? I am also not able to find a resource online to find a dis-assembly diagram for laptops or this Sony model at all, do you all know of an online resource to get this kind of documentation online so I can tuck it away in my toolbox?


Thanks in advance.

[FlyingPenguin]

Definitely sounds like a backlight issue, and if it's dependent on the hinge position I think you'll find that there's a bad connection somewhere. Maybe one of the wires in the ribbon leading to the display from the mobo is broken, or a cold solder joint where the socket for the ribbon is soldered on the mobo or LCD panel. Could even be a cracked trace on a circuit board.

HOWEVER if the position of the hinge is critical and totally repeatable, I suspect it might be the switch that turns the LCD off when the lid is closed. Is this a model with a visible mechanical switch? Some use a small microswitch with a pin that stick out so the lid will press it when closed, but high end models like Sonys often use a magnetic reed switch so there's nothing visible.

Either way it's a PITA to diagnose AND forget about schematics. I've dealt with Sony before. Unlike Dell and some other companies that put their service manuals online, Sony's policy is that no one but Sony certified techs are qualified to service their computers and they will not provide any service manuals to anyone else. Believe me I'd tried. They're very much like Apple in that regard and one of the major reasons I do not recommend Sony PCs.

[DaMaN]

Update after leaving the laptop on for an hour I was able to get it open to 70 degrees open without it shutting off. Another clue of a loose connection or broken wire / solder points.

I was also able to find a service manual for the following model number: VGN-FJ170. This number is faintly printed on the bezel of the LCD and I found a pdf of this model with all the goods I need for dis-assembly.

[DaMaN]

No visible mechanical switch on the LCD bezel.

Found the manual here: http://www.givemefile.net/smanuals/notebooks/sony/file/41833.html

Page 17 on that pdf does not list any switches but perhaps the ground cable or any part of the cable leading to the inverter for the LCD harness is broken.

I did find that cable for sale here: http://www.laptoprepairparts.com/partpicture_LRP.asp?ref=474&category=cables

[DaMaN]

I guess I have gone as far as I can go at this point. The skinny is that a potential client brought this to me to diagnose / fix and I am unsure if I should proceed and try to fix and how to bill for it - OR -give it back and advise him to go and get a new machine as it would be cost prohibitive and charge him a little something for my time. I am new to charging for repairs and time and want to be fair but unsure to re-coop some of my costs for time, any advice FP? I have spent a little over an hour researching it to this point.

[normalicy]

Laptops are hard to repair & make a profit. Really only worth doing if you know the issue before you mess with it.

[eGoCeNTRoNiX]

DaMaN.. I once had a Dell that did something similar to this.. If you shine a flashlight at the screen can you still see the image? If not, it could be the ribbon cable on the back of the LCD panel is coming loose when you open it all the way. If you can, it's probably a bad connection at the inverter some place.

GL!

eGo

[normalicy]

Chances are that it's a fractured ribbon cable or the contacts are bad. You'd be best by starting with the contacts that go to the motherboard. After that, I'd bet it's a ribbon cable. They're pretty fragile.

[FlyingPenguin]

DaMan: I don't even take on jobs like this. I send clients to a shop in town who has a sharp laptop tech.

As for what's right to do price-wise: if you didn't quote him a minimum ahead of time to open the laptop and look at it, then I would just give it back to him and tell him it's not worth fixing and give him a quote for what it would cost to transfer his data to a new laptop. Wouldn't hurt to price out some laptop recommendations for him at the local stores (just check the weekly flyers online for Office Depot, Staples, Best Buy, etc). He'll likely appreciate that you didn't charge him and you may get a call back later and still make some money off him. I assure you if you charge him for what he will perceive as doing nothing, you'll never hear from him again.

Sometimes it's worth taking a loss on a job just to maintain a good reputation and buy someone's loyalty.

[DaMaN]

Thanks FP, eGo & normalicy, I think I'll recommend a new one to the guy and tell him to keep my contact info so I can transfer data for him if needed. If it were mine i'd pry her open and give it a whirl. At least I have a resource for the future to look up repair manuals.

So all is not lost.

[Shadow250]

ive taken quite a few sonys apart, your problem sounds to me like the power wire from the inverter to the mainboard that they place right by the hinge. they use a seperate ribbon cable for the lcd. i usually charge 100 plus parts for a repair like that. sometimes i they indicate there gonna chuck it ill offer them 25 to buy it so i can play with it.

[DaMaN]

Although i chose not to do it I was thinking 120 + the part cost because I spent so much time researching it. Thanks Shadow.