Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

[kronikus]

Hi, I have trouble with my Toshiba Qosmio x505-890. Screen goes dark and webcam fail at same time. On external monitor everything works fine, HD resolution, 3D etc., but camera driver is represented by numbers and yellow exclamation mark. Display switching works but laptop screen stay black and brightness control is not working. Ccfl lamps are ok - tested with external inverter. On original inverter board input voltages are 19V, 3.3V, 0.2V and GND. Voltages are not changing on any command via keyboard.
Also, another LCD panel connected instead of original one, show same "picture".
Anyone have malfunction similar or same kind? Repaired?
Maybe damaged screen cable causes that?
If anyone have repair/service manual or schematics, please let me know!
Thanks

[ktmmotocross]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

that 0.2V is problem. it must be 3.3

[Djosla]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

It could be lcd cable fault so check that out...

Before messing with board...you could disconect 0.2v pin from inverter
(disconect wire pin from connector,leave other wires),and put jumper on inverter pins 2 and 3,so that you have 3.3v on pin that used to have 0.2v...This could be quick fix so that you can check that video output and screen/inverter works...

Downside is that you may lose functionality of brihtness adjustment ,or you might have to increase brigtness to max in order to have backlight turned on.It depends on what pin is mising,lcd enable or pwm adjustment...

[kronikus]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

Thanks for your advice. As soon as I turn on the laptop, the panels (original and spare 17") completely darkens backlight improvised with universal inverter. Light without any picture reappear for a few seconds during booting and turns black again. Laptop neatly switches the image to an external monitor and back (to the dark side ). I did cable measurement and everything seems fine. No interruption or short circuits. Unfortunately I do not have a scheme. The motherboard has a 40-pin connector, and to the screen goes standard 30-pin, 7-pin on the webcam and microphone and 6-pin on the inverter.
Is it possible that the defective lid switch keeps the screen dark and the inverter shut down and same time gpu send correct image on an external monitor?

Enyone has better idea?
It seems hopeless without schema...

[kronikus]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

I did some experiments last days. It turns that graphic card is problem, among others. When I pun another one, the picture came on 17"lcd trough same old ribbon. But again with no baclight. Than I borrowed and conected other, tested original complete screen ih housing with inverter and ribbon and again get picture but no backlight. Previously measured voltages on inverter connector did not change. Working perfect on external monitor...

Motherboard DATZ1CMB8F0 Quanta TZ1C rev:F

[kronikus]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

I did some additional measurement and find that complete DISPON line
are grounded as is visible on picture. Probably due to previosly bad damaged flat cable. Any sugestions?
It's so hard to find components scattered all around this huge mobo!
And anyone have board view for DATZ1CMB8F0 Quanta TZ1C rev:F motherboard?

[ktmmotocross]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

many transistors can be shorted. remove and check

[kronikus]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

Tried everthing that I can, without proper schematics and limited experience. At last I disconnected pin 27 of EC (Winbond WPCE775CA0DG) from board. and found that pin 27 (DISPLON) has only 1.1 ohm to the GND. Pad undernaeth pin has 11k ohm! That EC can't be good, or I'm wrong? And where is lid switch located?
TY

[meritosari]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

check voltage MR0

I thought its could work cause react with a small magnetic on LCD/LED frame

[highpulse]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

usually backlight on qosmio are due to 2 problems , bad "comparator" or gpu fault .

[Domp]

Re: Toshiba Qosmio x505-890 LCD goes dark and webcam fail at same time

I cant find out any info on the comparator. Is this on the card or the motherboard.