Tbh I'm not really expecting any solutions other than "replace the
mainboard" but I'll ask anyway in case someone has fixed the same problem...

Short version:

Toshiba P30-144 laptop.
Mostly this thing behaves dead with no lights. Very occasionally the AC
power and charge lights come on and then it will switch on and boot
normally only to shut down after a few seconds and then play dead again.
DC socket is fine, both CPU fans work and the heatsink has been cleaned.

More details:

From what I can see it seems to be going into some sort of protection
mode,in this condition the 19v supply is present on the DC jack and up
to what looks like the main voltage mosfet controller (can't read the
numbers on it) but no volts on the mosfets themselves. (there are 4 of
these which together provide 5v - separate from the CPU vcore ones)
There is what seems to be a 3.3v standby voltage but no other secondary
supplies function and the charge voltage to the battery is 1.4v.
What makes me think it's a protection problem is because as the dc
adapter voltage is removed there is a brief spike on the charge voltage
up to 15v and the secondary supplies come up very briefly.

Things I have checked by substitution - another known working CPU,
memory, backup battery and ac adapter.
I've also checked all the fuses and simple diodes, as well as the main
mosfets. The supply caps are those nasty smd cans that give problems
elsewhere but they check ok and I've tried replacing them anyway more in
hope over expectation

Given that I can't read the id on the main PWM controller, the age of
this thing and that any factory level diagnostics is definitely BER any
other ideas?

On Sat, 03 Dec 2011 17:50:34 +0000, Lee put
finger to keyboard and composed:

Short version:

Toshiba P30-144 laptop.
Mostly this thing behaves dead with no lights. Very occasionally the AC
power and charge lights come on and then it will switch on and boot
normally only to shut down after a few seconds and then play dead again.
DC socket is fine, both CPU fans work and the heatsink has been cleaned.

I couldn't find your model, but perhaps there are similar ones
(Toshiba NOTES)?
http://www.4shared.com/folder/0S3W-z...CHEMATICS.html

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On 03/12/2011 22:52, Franc Zabkar wrote:
On Sat, 03 Dec 2011 17:50:34 +0000, put
finger to keyboard and composed:

Short version:

Toshiba P30-144 laptop.
Mostly this thing behaves dead with no lights. Very occasionally the AC
power and charge lights come on and then it will switch on and boot
normally only to shut down after a few seconds and then play dead again.
DC socket is fine, both CPU fans work and the heatsink has been cleaned.

I couldn't find your model, but perhaps there are similar ones
(Toshiba NOTES)?
http://www.4shared.com/folder/0S3W-z...CHEMATICS.html

- Franc Zabkar

Many thanks for the link, the A80 looks to have some similar circuitry
and has given me some good ideas for things to check, not least all the
SI4800DY_SO8 this thing uses a truck load of them...

Lee