T40 Power light flickers

[HayLo]

Hello,

Got a t40 with wierd power issue.

When you hit power button, the light just flickers (on-off).

The fan will actually move tiny little bits to the flickering.

My guess is short of course.

It doens't seem to be the usual GPU issue, fuses all look good. Swapped ram/cpu/ and powerjack. Does this off battery too. Filters seem to be good as well. (filters cause simular, but its not that issue).

This is just a shorting issue, but not sure where to check next. Worked, then next second doesn't.

Thanks in advance for any tips...

Matthew

[Harryc]

If you remove the RAM then power up, does the board beep? Try removing any mPCI cards and modem cards too.

[HayLo]

All cards removed...

No ram = no beep code.. no post at all.

...

[Harryc]

What is the output voltage on your AC adapter as measured by a multimeter? Should be 16vDC ...

[poshgeordie]

I'd also remove the Hard and CD Drives too - in fact I'd (carefully) take the motherboard out of the base and test it on a non metal surface (we do this all the time).
Refit the CPU, heatsink RAM and Screen LCD cable and then try powering it up. You could also try running it without the LCD cable attached to check the cable's not causing the issue - it's probably unlikely since there's so many fuses protecting the LCD circuits.

Also since it's out of the base, closely inspect the motherboard to make sure something's not causing a short.

Also check if the Southbridge chip is getting extremely hot from when you power up. Sometimes it can develop internal short circuits and goes from cold to mega hot in no seconds flat!

[HayLo]

SOLVED:

Shorting USB, bah, i blame lack of coffee

Thanks for trying guys. Laptop back together and booting

[poshgeordie]

Pleased to hear you've found it - I'll add that to my list of T4x problems and solutions.

When you say it was a shorting USB what exactly was this - was it a faulty USB port in that one of the pins is bent (not uncommon) and shorting, or was it a faulty USB device that was causing a short when plugged in?

I have seen it where if a USB device is plugged in at an angle, it's possible to short out the port and shut the laptop down.

[jjspicoli]

I too am having the same issue, can you elaborate on the fix you did? I hope it hasnt "bricked"