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Laptop display question

Last response: in Laptops & Notebooks
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November 7, 2011 2:38:12 AM

I have a compaq presario cq40 541tx that somebody sat on, breaking the display and the mainboard.

I have replaced the lcd and the mainboard with new items. after I power it up, the heatsink fan starts up. but the diplay remains black.
I connected an external monitor to the vga port, it also remains black.

after power up like I said the fan runs for a couple of seconds, then it stops. after about 5 seconds the caps lock and number lock leds flash a trouble code of four. (Four flashes then a pause then it repeats)

according the the explination for the codes on their site, it says "Graphics controller is not functional" this is a new motherboard that I just installed in there.

So my questiin is as follows: if the motherboard is good, can I have the laptop display disconnected from the motherboard and just use the vga port connected to the monitor?

and if this is the case, then would this be pointing to a bad graphix controller on the motherboard if the monitor remained black too?

The monitor is a good one, I use it for display on my laptop.

Thanks,
Robert
November 7, 2011 3:05:09 AM

It sounds like your system may have had a graphics card. this would have been a removable card that could be still on your old board and you didn't fit it to the new board.

Or you have a dead graphics card as well as the screen and motherboard.

You will need a graphics card (either onboard or seperate card) to get the display to work (either internal screen or external monitor.

by the sounds it would have been easier to replace the whole unit. as a motherboard is typically about 80% of the orgional purchase price of the laptop.
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November 7, 2011 3:31:18 AM

The board that is in there has three places on the main board. One is the processor, the others are an Nvidia 3d processor and a AC82pm45 southbride chiset, these all came on the new board. (all except for the processor which I swapped to the new board)

The Nvidia processor looks to be hot glued at the coners of the board, but I do not see a socket under that processor.

As far as I can see it is road ready to go. I just can't explain the blank screen except for the fact that it would seem the the graphix controller ( in this case the Nvidia ) seems to be bad.

I'm just looking for a way to verify this.

Hence the question, if the laptop display were to be disconnected from the main board, would the Vga port still be usable?

The cost of the board was very cheap as I'm in China right now where it was made, In the US they wanted like 1k for it. But over here I got it for under 100.00 USD.
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