HP - CE Series - DAG7ALMB8C0 REV.C - MODEL - G7AL-2G - Missing MAINON & SUSON - Turns on power LED & Charges

[reessi]

Hello,

I have re-soldered the loose pins on the RAM slot which is a common fault on these models..

It charges and turns on the power LED but is missing several voltages like RAM and CPU do not come up which I believe is due to MAINON & SUSON being missing to turn these supplies on..

What I am un-sure of is what is the ITC chip waiting for to send out these signals, what are the requirements?
I have checked these lines in diode mode and they seam normal -> 600.

I have checked to see if they come on for even a fraction of a second on power on but nothing.

Can anyone explain the sequence on the board for the ITC chip to send these out?

1.8v, 3.3v & 5.5v come up when turned on with the power button.

And there is power on the BIOS.. What I also want to know is, is there communication between the ITC and BIOS before the CPU is up? And if so can a corrupt bios cause this?

I have the schematics and board view from this forum.. I can attach again if required and also photos if required.

There is no power on the RAM or CPU as they require the MAINON and SUSON.

Another query I have is, does it make a difference to which power rails come up if there is no RAM in the slot.. Does it detect for the presence? Just wondered.. I have RAM.

I cannot find any shorts on the missing power rails..

Also what voltage will MAINON & SUSON be when they come up and are both required to turn on the power supplies?
Also what would happen if I inject these voltages on these signals? Presumably the power rails will come up but I guess there is another problem anyway as to why the ITC won't send them out?

Many thanks.

[reessi]

UPDATE:

After reading online about the power sequences of various motherboards I found that after the power button (NBSWON1# into ITC) is pressed then ITC relays that signal to the PCH (DNBSWON#).

These signals happen as expected but then PCH is supposed to send SUSC# back to the ITC which in turn should turn on everything else with SYSON. But it does not send this signal!

SUSC# is not shorted (800 diode mode). So either the PCH is faulty or there is something the PCH is expecting first.

I experimented by injecting 1.8v on to SYSON and MAINON and DRVON and sure enough the power supplies come up but no post from the motherboard, presumably the ITC halts until it is receiving SUSC# and the PCH is obviously not running properly anyway!

I will continue to read up on it. Any advice appreciated...

[reessi]

Can anybody help please? I do not know where to go from here?

Many thanks.