820- 2532 not posting (not normal poly-tant problem)

[Repairable]

did you replace the poly-tant,
or did you place a bigger 330UF ????

 

[larossmann]

Usually some corrosion on CPU vcore regulator U7100 on the edge of the board. Look close! Those little holes where something travels from one side of the board to another.

 

[dukefawks]

You have liquid damaged board and are replacing caps....Logic would say something is corroded, this is not a cap problem.
When the machine does not boot, are all voltages present especially CPU Vcore?

 

[samiam]

so PPVCORE_S0_CPU is reading .99V instead of 1.25V
CPU is getting warm
which brings me to the U7100 circuit where I was already thinking of doing the poly tants C7117 and C7155

i've never worked on this circuit before, going to watch some more rossman vids, any other suggestions/ tips?

 

[dukefawks]

.99V on CPU is fine, it is a dynamic voltage set by CPU. This could be anything, corrosion somewhere under some chip. Only you saw where the corrosion was.....

 

[samiam]

PP1V05_S5_MCP is reading 1.1V, is that too much?

 

[dukefawks]

Also fine. The corrosion was not there....

 

[samiam]

really not sure where to start, guess i'm going to have to go thru and measure every line and hope something shows up weird, powers on and fans run high but no post.

there was residue but almost no corrosion. only real corrosion was around some USB caps (C4605, L4605 and C9480 and C9481), I was getting 4.2V there, cleaned and now getting full 5V and 3.3V.
only other stuff that whatever liquid it was touched was the main ISL and C9590, realtek ethernet, and that whole firewire stuff next to it

any suggestions, i was assuming it had to be cpu, gpu or ram since it did post a few times, now i'm no longer getting any post no matter how many times i try

 

[dukefawks]

Remove fire wire chip