TFT Screen problem (Toshiba TECRA 730CDT)

[hicks78]

Hello, I'm looking for some directions to try resolve this problem.

I have this old notebook, Toshiba TECRA 730CDT, it works but the screen does this weird effect and I'm not sure if its caused by the screen itself or the video chip/card (or any other component?)

As you can see in the images its like every one line gets shifted to the right, and it gets worse to the right side of the screen.

I already reconnected/tighten cables from the motherboard to the screen and the flat ones on the TFT screen itself.

The screen is a SHARP LQ12DX03 12,1" TFT

Inverter seems to work ok, it has good back light so I guess its not the inverter (?)

Does anybody have a clue or where is the origin of this problem (and maybe solution)? Thanks!

 

[kellys_eye]

Try changing the screen resolution/refresh rate.

 

[bertus]

Hello,

As @kellys_eye said, check the resolution and refresh rate:
The screen seems to be 1024X768 @ 60 Hz:
https://www.panelook.com/LQ12DX03D_Sharp_12.1_LCM_overview_9920.html

Do you have the maintenance manual?
TECRA 730CDT maintenance manual

Bertus

 

[hicks78]

Hello,

As @kellys_eye said, check the resolution and refresh rate:
The screen seems to be 1024X768 @ 60 Hz:
https://www.panelook.com/LQ12DX03D_Sharp_12.1_LCM_overview_9920.html

Do you have the maintenance manual?
TECRA 730CDT maintenance manual

Bertus

Thanks Bertus and Kellys_eye, yes I had that PDF, used it to dismantle the screen.
But there is no info about how to change screen refresh rate, at least on MSDOS, will try with windows 95.
I searched for a DOS program to change screen resoultion + refresh rate with no luck.

Anyway, I wonder how the refresh rate would not be the right one on a old laptop like this. Its supposed that Toshiba already uses the optimal refresh rate on the BIOS or video chip (or whatever controls it).

I think its a hardware problem, as the "lines" or the "blurryness" its worse on the right side of the screen.

 

[bertus]

Hello,

Is the first picture from the BIOS?
It shows VGA compatible (640X480).
Are there other settings like SVGA (800X600) and XGA (1024X768)?

https://en.wikipedia.org/wiki/Video_Graphics_Array

Bertus

 

[Bluejets]

If it has an external monitor socket you might try that.

 

[hicks78]

Hello,

Is the first picture from the BIOS?
It shows VGA compatible (640X480).
Are there other settings like SVGA (800X600) and XGA (1024X768)?

https://en.wikipedia.org/wiki/Video_Graphics_Array

Bertus

Yes it is from the BIOS, the other option is "Disabled" and not sure what it does but I tried it and nothing changed (it gives an error when booting again and goes back to "VGA compatible".

I tried changing everything on the BIOS, even if its not related to screen, just in case. With no luck.

If it has an external monitor socket you might try that.

Yes I did that, with external monitor the image is crips and clear. The problem persists on the notebook screen.
There is an option in the BIOS to select between "Only internal or external" and "Simultaneous" where you see image on both screens at the same time. The issue on the notebook screen its always there, no matter the option selected.


I'm almost convinced its hardware problem, but still not sure if the problem comes from the motherboard/vga chipset or its on the screen itself. I almost dismatled the scren compeltely and re-assembled it again, but no change. I dont see anything wrong on the screen circuit board or cables.

I appreciate your answers. I will continue trying to locate where the issue comes from.

 

[kellys_eye]

Has the device been dropped at any time or dismantled/rebuilt?

It looks as if the LCD filter may be out of place - touching at the left side, gradually increasing in separation as you approach the right hand side.

If you HAVE dismantled it did you go as far as separating the individual layers that make up the LCD itself?

 

[Bluejets]

If the pic is fine with external monitor that sort of rules out the laptop video driver section and points at the display itself as Kellys_eye suggests.

 

[hicks78]

Has the device been dropped at any time or dismantled/rebuilt?

It looks as if the LCD filter may be out of place - touching at the left side, gradually increasing in separation as you approach the right hand side.

If you HAVE dismantled it did you go as far as separating the individual layers that make up the LCD itself?

Doesn't look like its been droped or had any big impact. And it didn't seem that it had been open in the past when I did it.
Its in quite good condition, external and internal.

About separating the individual layers inside the screen, I did that in the past with broken monitors just to see the internals of a LCD monitor, but I saw it as a complex/delicated part and this time didnt want to go that far as I was afraid to make it worse. But maybe I'll do it next week if I can't see any other solution. If I do I will post pics here.

 

[hicks78]

Today I dismatled the screen. The layers where fine. I did test it without the backlight layers and, as you can see in the photo, the issue persists:

(I used a phone light behind)


Here is the screen board, it seems ok:

Some more pics just in case:

After assembling all back together, same as before. (at least I didnt make it worse!)

Is it worth trying something else?

 

[kellys_eye]

Can you run any other software than the boot screen?

Try finding a 'test card' software such as this: https://www.eizo.co.uk/accessories/software/monitor-test/

post your findings.

 

[danadak]

Long shot, but sure looks like a lost ground connection or power supply problem
causing 50/60 Hz modulation of a timing input......just a thought.


Regards, Dana.

 

[Martaine2005]

I’ve had similar problems but with desk tops. Shielding and keeping cables away from each other usually fixed the issue, so a laptop grounding issue could be very likely.

Martin

 

[hicks78]

thanks for the new answers, but it seems I made it worse...

Now the screen only shows a white full screen:

No mnatter what I do it only shows that white screen. I give up!

 

[danadak]

Do you have a good magnifying glass to look at soldering and flat ribbon connectors ?
Good lighting a must when you do it. Cracks in soldering joints, oxidation......bits on
detritus inside flat ribbon female connectors.

A fine wire brush to clean connectors (the ones you can access). Gentle is the operative word.


Regards, Dana.

 

[hicks78]

Thanks Dana, I don't have mangnifiying glass, but I think I can use the phone. Will do.