t40 power up problem *PIC*

[xyz]

Tried a different non ibm type lcd in the laptop it powered up then immediatley powered off,

So now witht he normal lcd get the same think powers up then immediatley powers off.

If i Boot up with the memory module removed the board gives me the 4 beeps.

So not sure what is going on here .. any one have some ideas ?

[The Spirit of X21]

This should help tell you what the beeping means:

http://www.thinkwiki.org/wiki/Error_Cod ... Beep_Codes

[IBMbuilder]

The mother has been fryed already. You can disconnect the native LCD and boot with external monitor. It will boot, but that's it.

The LCD selective control circuit has been shorted dead. When the power control sensing a short in LCD circuit, it will immediately shut down your laptop to prevent damage to the LCD, but in return the motherboard itself can only boot with external monitor. try it, you will se.

[richk]

Before deciding it is cooked, at least try to reset it. Unplug, pull main battery, pull CMOS battery. Then press the power button a few times, holding it a full 10 seconds the last time. Put the memory chip in, replace the batteries and try again to start it.

[xyz]

Re Ibm Builder

Yes you are 100% correct boots with a external monitor gives some garbaged signal.

Any idea why this has happened ?
Also is it possible to repair I have access to a few donor boards that have had some problems but nothing like this.

[NS]

<Snip-snap>boots with a external monitor gives some garbaged signal.

Any idea why this has happened ?

Something has corrupted. Not all thinkpad motherboards can fit into that particular thinkpad model of yours.

Sir, may i know which part of the globe are you located at?

[xyz]

From the uk.

Nothing wrong with the motherbaord was orginally in that thinkpad.

Just trying with the non ibm lcd panel that caused this problem.

[IBMbuilder]

Do you what cause that? hehe, that's you. you said that initially the laptop was fine, then you connect it to an alien lcd, one of the power circuit pinout of the mobo is grounded with the LCD, and I'm sure that one of the power transitor on the board fried, that it grounded itself, so everytime you turn the laptop on with the native lcd attached, it will power down to prevent damage.

If there is no lcd attached, it still boot fine with external monitor, because the lcd control circuit is isolated. It kinda complicate to go further.

Sorry.

How to fix it? send the board to me, hehe.

[xyz]

Ok i understand all that.

So now the problem lies with the power transitors ?

A matter of swapping them out ?

Which ones do i need to replace ?

[SMA]

I would be looking on the motherboard for something like this

http://www.rkawakami.net/ibm_t2x/let.jpg

[IBMbuilder]

Do you have a BGA station? Hot air station would do. The native selective lcd controller chip located under the pcmcia cage labeled ibm 77p2951. It is a square 100 pin chip. Do it at your own risk.

Most LCd have 3.3V LVDs bus, and often have pin 1-2 as ground, 3-4 power 3.3V , but ibm has it other way around. This is the reason why your native lcd does not work after you attach the wrong lcd to the system. what was the alien lcd you attach to IBM lcd cable? samsung, hitachi, LG...

[xyz]

I used a I think a lcd from dell can give the exact model number etc.. later.

I have an ibm chip labelled 26p1783 pmh4/ yamato
this is just under the bios chip I take it this is the chip to extract.

If its this one then it shouldn;t be toohard.
Is it just the chip that needs changing or is there soemthing else too ?

[xyz]

Yes hot air station I have access to.

IS this the chip we are talking about the one circled in red ?



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[DrColossus11]

I'm having the exact same problem, but I used a screen from another T42p.

[IBMbuilder]

Yes that is the LCD controller driver chip. THat chip make selective switching mode for LCD. I wouldn't know for sure replace it would fix your problem.

[xyz]

IS there anyother transistor or power mosfet that needs to be replaced too ?

Will do the repalcement in a couple of days and post back how I got on.
Should be fun

[xyz]

Right now I get 1 long beep and 2 short beeps any ideas ?

[GomJabbar]

Right now I get 1 long beep and 2 short beeps any ideas ?

That information is in the Hardware Maintenance Manual for your ThinkPad.

One long and two short beeps is one of the following:
1. System board.
2. LCD assembly.
3. DIMM.

[xyz]

Reseated the chip and now its powers up but get nothing.
If remove the memory get the 4 beeps so cud it be the controller i put in is faulty or am i missing some thing ?

[IBMbuilder]

OK now it power up, remove memory then it beep that mean mobo is not dead. LCD connect but get nothing? the source that cause laptop to shut down when LCD connected has been removed(your LCD controller chip). I guess the soldering part has faulty. Check all the pin make sure there is no short, and all connected to the board.