T43 lcd cable problem?

[storm525]

Hello there!

I have some strange problem on my T43 1871 FAG, I think it´s intel graphic there. The screen is dimm/dark, I can see the Thinkpad logo at the startup, but backlight doesn´t go on. I checke the inverte by replacing it with working one from R51e, there is no problem, I also checked the backlight on my R51e, also no rproblem, so inverter and backlight are both working. External display is also working without a problem.

Did anyone have a problem like this? Is it in lcd cable, or is it something wrong with the mobo?

When I move the lcd cable, there is no change, screen is still be dimm..

Thax for your help guys.

[RealBlackStuff]

Welcome to the forum.
Your problem is the CCFL (backlight) on your T43 (which does have an Intel 900 GPU).
That needs to be replaced.
It probably showed a reddish/pinkish hue for a while before it died.

[richk]

There is a fuse on the motherboard that blows sometimes

[gb]

Hi,

I have very similar issue with my T43. I was completely sure it is backlight, because I still can see some ghost image. But when I have purchased another LCD assembly from e-bay and replace it, it still shows the same problem. Works fine when connected to external monitor.

what could it be? and what else I can check?

[storm525]

Hi guys!

I do not believe, it might be the backlight or inverter, ´cos I checked them both on another Thinkpad, and they are both working.

Where can I find he fuse? Any pics? When it´s gone, the whole mobo should be dead, isn´t it so?

I´ll give a try with replacing the lcd cable and then I will see....

[rkawakami]

Another member here ( poshgeordie) has posted a T4x fuse map: http://nickpaton.fireflyinternet.co.uk/ ... 0Fuses.pdf

Don't know if it can be applied to a T43 but there is a good chance that the same types of fuses were used as on the earlier T4x systems. There are many fuses on the motherboard; each one protects a specific part or subsystem.

[poshgeordie]

Welcome to the forums Storm

I think it will be a fuse - not an uncommon problem.

The fuses layout for the Intel GPU based T43 will be different to ATI based boards, but there probably will be layout similarities for the LCD fuses.

If you can get access to a multimeter to check the continuity (Ohms check), with the Thinkpad powered off and the battery and AC adapter removed, check:

F7 - LCD System DC
F8 - LCD 3.3V

Alternatively you may want to send it to myself at Reflow Repairs (see blue advert at the top of every page) and we can sort it out for you.

Typical price for checking and renewing fuses will be around £15 (special TP forum member's price!) with unfortunately return carriage to Slovakia around £30 (what it costs me).

PM me if interested or want more advise etc.

[storm525]

Hi guys!

So I checked the MB´s fuses...I founf F2, F3, F7...all the fuses I found seemed to be OK, but where on earth could be the F8 fuse?

I tried also another LCD cable, still be the same result...no voltage is coming out of the inverter. I checked the plug and there were I think 5 times around 3,3 volts on it, but that was all.

Could anyone tell me, where can I find the F8 fuse? Is it near fuse F5 or so? There were 2 fuses with 3,3V flowing through it.

As a I read some other topisc, F7 should be the inverter fuse, but it had around 16 V coming in and out...where should be this voltage checked on the lcd connector?

Thanx in advance.

[poshgeordie]

Hi Storm

When you say you have no voltage coming from the inverter, do you mean you have no HT voltage to CCFL tube? How did you verify this?

I've just re-read the full post again and to summarise:

1. Dim image on screen.

2. Tried T43 inverter and LCD cable on R51 and both work OK.

Next step - try the R51 screen assembly (LCD panel, Inverter, Cable) in the T43.

If that that gives a dim screen again it's back to the T43 motherboard. Fuse F8 is for the generic ATI based motherboard and if you scroll to page 3 of the fuses diagram you'll see F8 connects via a thicker piece of track directly to a couple of pins on the RHS of the Display Connector.
It may be that on the Intel chipped T43 it's got another ident.

Hope that helps.

[storm525]

OK, so here is the update....

Since I couldn´t try it with the R51e LCD, I just measured the voltage on the lcd cable plug. Funny thing is, that even all those fuses (I found F8..) seems to be OK, and giving voltage, no pin on the plug is giving around 16 volts, which are coming out of the F7 fuse, there are only some 3,3 and 0,8 volts.

So where should I search now?

Thanx