Notebook LCD problem


Old 02-05-02, 07:55 PM
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Notebook LCD problem

Any thoughts on a Sony LCD port (C1VN) with very dark screen. Can see image though. Everything else works fine - ext monitor, TV -all video tests are nl. I have tried new LCD, new inverter unit, new cable connectors. Nothing helps. Has ATI video on Moth Board - checks out OK. Just seems power to LCD (only) is weak.
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Old 02-06-02, 01:49 PM
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Cool Flo tube

I would almost bet what you have there is a florescent tube failure. Those screens are backlit by a small flo tube and if the tube has failed the screen will appear dark. If this is out of warranty then I would take the LCD screen section apart, carefully block it so as no components are touching metal etc and turn the power on. Look for a tube that will actually be covered but you will still see it come on, comes onÖ If you donít see that back light on there is you problem. This is assuming you have gone thru the software and the brightness/contrast controls are turned up etc. Weíll go from here.
Old 02-06-02, 06:29 PM
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We replaced the LCD with a new unit with the same result. Everything that has been suggested short of the motherboard - has been replaced with no change.
Old 02-06-02, 08:14 PM
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Cool Repair

Well I guess send it in for diagnosis and possible repair. There are diagnostic tools made to do this and I will have to do a little research to find them. They are designed to check out the mother board etc. How old is this? If itís older than 2 years then I would replace it. Notebooks are so cheap now compared to just a year ago. 1.2 gigs with all the bells and whistles less than a grand. I have no other ideas, for you, if you have been this through then itís time to decide if professional repair is neededÖ
Old 02-07-02, 05:54 AM
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Thanks for your help. The unit is the little Sony C1 just over 1 yr old-just out of warranty. My problem is I've invested $500 thus far -in addition to the orig cost - I'm emotionally irrational at this point! (Don't tell my wife)
The moboard cost about $800 from Sony--the whole unit on ebay is about $1200.

The LCD screen is visible but very dark -and an ext monitor and TV works fine - as does everything else. I've replaced cables - screen, inverter. I can't figure out what else could give this combination of problems - unless I have replaced a bad part with another bad one (unlikely) or some other component is knocking off the part?
Old 02-07-02, 07:25 AM
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Cool Lites?

So the florescent back lights are lighting? Plus sending it in for diagnosis will not cost as much as you have spent so far. And they will tell you what is wrong. You sound like you have a grasp on how to repair it so get it diagnosed and fix it. If all the drivers are in and working, the back lites are lit, external monitors work so the display device is running. You have it setup up as default for the LCD when no other device is connected. The character generator is running, I would say the luminance circuit for the LCD has failed. Without a schematic I canít go any further. If you have a schematic then look around the luminance section
Old 02-07-02, 10:39 AM
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Thanks again! I have the "service manual" from Sony. It shows a flow chart - elect parts diagr- block diagram - frame harness diagr - LCD assembly diagr, etc -
The LCD attaches to motherboard with one 20 pin harness -nowhere else!!
The harness is near the ATI chip which is next to the MJPEG chip.

The block diagram shows the PCI bus (3.3 volts) on one side then the LCD attachment on the other (not a schematic per se -but its all I can get!) The external monitor stuff(which seems fine) comes from same place as LCD harness!

I'm not sure where or what the luminescense area is? But I think its all been replaced. Could the ATI chip be faulty? (or something to do with power to LCD assembly??
Old 02-09-02, 02:38 PM
Join Date: May 2001
Location: Carol Stream, IL
Posts: 338
You can shoot me later if this comment is inappropriate but...

did you try adjusting the contrast and brightness using the keyboard shortcuts? The video output for the lcd is different than the output to the VGA port.

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