820-00426 3 beeps

[2click]

Hi again, I´ve got this board which was working, I first turned on and work on the computer fine, but when I left it and it whent to sleep I found the problem that was reported. I have 3 beeps as for memory, as it is beeping I measured PP1v35_s3_mem = 1.35v, so I just want to know if this model is known for that kind of problems, or is it worth it to reflow the memory chips? thanks!

 

[2informaticos]

3 beeps code error is caused by bad communication between CPU and RAM; not because of missing RAM voltage.
I don't remember to heard about classic issue related to this problem on A1398.

 

[piernov]

You should check at least PPVTT_S0_DDR and MEM_RESET_L, but it's probably an issue related to the RAM chip themselves.

On 820-3332 it can be caused by physical stress pretty much like U8900 and a reflow may fix it for long enough, but on newer A1398 the issue has been mitigated with better board support so it's much less likely to happen (doesn't mean it cannot happen). This can also result in damaged pads which would not be reasonably repairable.
Of course it can be failed RAM chips even though it doesn't happen often.
Still, a RAM reflow followed by several passes of Memtest is worth a shot…