Apple macbook 820-3115b strange behavior, please help!

[justin35]

I have an 820-3115 board which acts strange, at least for me.
Board looks clean.
Green light present and flases 3 times quickly then fan spin for 3-4 seconds. Then it turns off again green light flashes like 7-10 times then fan spin again...
Clock is 32.776
If it's in enclosure i can hear cd-rom activation, but nothing else, because it reboots.
If i unplug ram stick, green light flashes 3 times, then fan spins, and i get ram warning beeps...

Any suggestion?
Thanks!!

[piernov]

Re: Apple macbook 820-3115b strange behavior, please help!

Battery unplugged, using known good Magsafe 60W or 85W? Tried another DCin board?
Do you have a lab PSU with Magsafe cable to check the current consumption?

Also make sure voltage on PPBUS_G3H is stable at 12.6V.

[justin35]

Re: Apple macbook 820-3115b strange behavior, please help!

Tested with a good known 60w and 80w magsafe. Changed 3 dc in boards...
I will hook up psu to check power later tonight...

[justin35]

Re: Apple macbook 820-3115b strange behavior, please help!

Well i hooked up psu with 18.5v and 4 amps limit...
I get the following amperage drwing:
First fan atempt after connecting magsafe is always shorter
0.02 > 0.03 > 0.82 spike > 0,75 > 0,03 (about 2-3sedonds /cycle)
Second third and so on fan stays a little longer (almost 6-7sec /cycle)
0,03 > 0,71 back and forth to 0.69
0,82 spike
0,74 > 0,75 > 0,03

Without ram installed, board is spinning the fan constantly and graduates the speed up to maximum. Also ram warnings are present on speakers...

While the board is off and green light is flashing, i can hear a clicking on the board but i can’t tell where is it come from...

From previus days experience, with a shorted pch on p3v3_s0 it was also flashing green light and clicking.
Removed pch, short and clicking is gone , of course without new pch installed as i don’t have proper equipment.
This means when the board is clicking it has a short?!?

Also, i found out a little history of the board:
Laptop had a faulty “2 key” on keyboard, so the owner swapped the keyboard.
First 2 atempts was a used unknown condition keyboard which had far more dead keys.
Third atempt was a good keyboard but “2 key” still didn’t work.
Forth atempt laptop was rebooting...

Ps: i foud some liquid residues on cpu radiator grill, it looks like it had some liquid afterall...

[justin35]

Re: Apple macbook 820-3115b strange behavior, please help!

Case solved!
It was r7553 which was half way knoked off the board...
It took memsome time to see it.
Anyway, board boots, works ok.
The clicking is no longer present..

[piernov]

Re: Apple macbook 820-3115b strange behavior, please help!

Good job! Wouldn't have thought of this one, although it somewhat makes sense that the issue was on the VCCGFX supply, as without RAM it was beeping normally but with RAM it was cycling. VCCGFX rail will not come up when the board is not POSTing (and it'll not POST without RAM).
I just didn't think of that at all… Thanks for the report.