t20 black screen at startup

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fr0zenmon · #1 Post by **fr0zenmon** » Mon Sep 17, 2007 7:43 pm

I started up my t20 the other day and the computer turned on but nothing was on screen. I tilted it and then the screen appeared then disappeared. is this a lost cause?

jamerslong · #2 Post by **jamerslong** » Mon Sep 17, 2007 11:38 pm

sounds like a loose connection, Bulb plug may be loose? can you see the screen in a bright lit room?

remove the Keyboard and check the Video cable connection, it if it seated well then remove the LCD frame (simple) and check the inverter

Robbyrobot · #3 Post by **Robbyrobot** » Tue Sep 18, 2007 4:20 am

Unfortunately, this is by no means unusual. The causes range from a bad backlight (LCD panel) through the inverter/flat LCD cable and the mainboard connector right up to a mainboard defect.

If you're lucky, the problem will simply be that the mainboard connector is poorly seated: reseating it will solve the problem. If that doesn't help, you'll pretty well have to have some spare parts (best is to buy or loan a used/working display complete for testing). If it's not the display, then it could well be a mainboard (graphics) problem.

I have a T21 where the backlight doesn't work (LCD display completely OK), but an external monitor works fine, and in this case I apparently have a mainboard defect. Incidently, the symptoms were identical to what you describe: moving the screen back and forth sometimes lit it up.

jamerslong · #4 Post by **jamerslong** » Wed Sep 19, 2007 1:46 am

robbyrobot, have you tried replacing the entire LCD including the mainboard cable and inverter for testing? it sounds like a poor connection and the very worst situation would be loose or bent connecters on the motherboard?

Robbyrobot · #5 Post by **Robbyrobot** » Wed Sep 19, 2007 9:28 am

robbyrobot, have you tried replacing the entire LCD including the mainboard cable and inverter for testing?

Yes, and unfortunately the issue wasn't as simple as I had hoped. I've had the board hooked up to several known working displays (LCD panel, cable, inverter assembly) and none gave more than - in one isolated case - a sporadic and non-reproducible backlight, although an external monitor works just fine. All the displays work perfectly on another T21. Like it or not - and I don't, obviously - this appears to be a mainboard issue.

jamerslong · #6 Post by **jamerslong** » Wed Sep 19, 2007 6:39 pm

it just sounds so weird, i dont see how opening and closing the lid would cause it to flicker for any reason other than a loose wire, the only thing i can think of is loose components on the board.

#7 Post by **rkawakami** » Wed Sep 19, 2007 6:59 pm

Have not seen any mention of the lid switch so far... that can also cause problems with the backlight, especially if you have specified "no action" to be performed when the lid is closed.

dogma420 · #8 Post by **dogma420** » Fri Oct 05, 2007 12:57 am

From past experience, this is probably a bad switch that is telling the system the LCD is closed, therefore it is turning off the backlight on the LCD.

The switch is in front of the keyboard, upper right. Check it by going into power settings with external monitor and under "when I close the lid of my computer do the following" change it to 'do nothing'

or

using a pocket knife, lift up on the switch....

This is a very common problem and when it could be a bad lcd, bad inverter, bad cable, it is about 33% of the time just the spring on that switch that needs to be bent, or a new keyboard bezel is needed.

Good Luck!

dogma420 · #9 Post by **dogma420** » Fri Oct 05, 2007 1:00 am

Actually, cancel the power setting change--

that won't change a thing if the LCD is closed switch isn't working--best thing to do is do the pocket knife trick or remove the keyboard bezel and turn it on and test.

joester · #10 Post by **joester** » Fri Oct 05, 2007 5:34 am

I thought I might have some switches that could replace the lid switch, but it's SOT23 style. I don't have those. I do, however, have a spare back panel board (the one with all the connectors along the rear of the base) that has the switch on it.

dogma420 · #11 Post by **dogma420** » Fri Oct 05, 2007 1:57 pm

Actually, what I was talking about is the physical piece of plastic attached to the metal spring (well it isn't a spring per se but it acts as one)

NOT the actual electrical part on the board--in all cases, this is not the part that is defective.

Over time, the lcd switch, from use, just bends out of shape, and eventually it doesn't come back up after the LCD is lifted, so the machine thinks the LCD hasn't been opened, and the LCD stays dim.

joester · #12 Post by **joester** » Fri Oct 05, 2007 11:12 pm

Haven't had that on mine, but I can see how that could happen. Just the same, I have a spare if anyone needs it.

Joe

t20 black screen at startup

t20 black screen at startup

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