Thinpad T43 boot failure

[Lean]

Hello,
IBM T43 fails at power-on. Green leds lighted and black screen at all. No image from external monitor output.
MotherBoard schematic as ROME-4 SVTR.
Seems to be a defective capacitor. But, as shown in the schematic, there are plenty of inverters using possible faulty tantalum capacitors.
These are generally systematic faulures, caused by a single damaged component.
Does anyone know wich capacitor could be the damaged one?
Thanks in advance
Lean.

[vinceroger69]

Re: Thinpad T43 boot failure

dont know if this is worth trying
http://forum.thinkpads.com/viewtopic.php?f=2&t=102977

[dan8139]

Re: Thinpad T43 boot failure

Does the 'hold the power button down with all power removed' stuff really do anything?

Hope you get it going, I like the T43.

[vinceroger69]

Re: Thinpad T43 boot failure

no idea but hey its free to try seen it posted on lots of forums i have the t42 my self quite good imo.

[Lean]

Re: Thinpad T43 boot failure

Yes, I've tried with no results

Thanks for your reply.
Lean

[Lean]

Re: Thinpad T43 boot failure

Hi,

Thank you all for your reply.
I think there is an inverter out of work.
This weekend i'll be studying this matter with the oscilloscope.
Best Regards
Lean

[vinceroger69]

Re: Thinpad T43 boot failure

but if the invertor faulty it should work on a external monitor? i wonder if the gpu chip is faulty ie needs reflowing/re balling. t42 suffer a lot from this problem.

[dan8139]

Re: Thinpad T43 boot failure

Yes the (ATI) chip has weak solder and the board flexes if the laptop is picked up by the bottom corner. The ones I've seen still boot in this state though. Try clearing the CMOS (battery under RAM cover I think).

It's not a bad inverter.

[Lean]

Re: Thinpad T43 boot failure

The failure comes just only at power-on. Once it has booted, it works perfectly. This rules out the flaw in the video chip. So, I must think at processes that occurs only at start-up.
The reset infraestructure is complex enough to be handled in a simple way. I manualy reseted U61 (TSURUMAI, pin 58), with no results. Signals seem to arise correctly, but they are so many that couldn´t evaluate all of them.

The computer makes no sign to be booting, though the process of reinstalling the bios via crisis diskette / LPT key seems to complete succesfully.
Ofcourse, after completing the bios reinstall, all cmos data are cleared to defaults.
The symptoms could be compatible with a faulty EEprom reading used beyond the maximum writing cycles.
if the fault lays in the dynamics of a process, I would not be able to discover it.

Best Regards
Lean