Ipad 4 Irregular Voltages and 0 amp draw
Hi, any suggestion is highly appreciated because I'm in a state of depression rn thankyou :D.
Disclaimer, I usually do a laptop repairs so mobile repair is not my specialty, sorry if my approach you found somewhat dumb.
the ipad comes with no display problem with 0 amp current draw, upon checking i found the voltages around the board (when the power button is pressed) is pulsing like 3v and goes back to 0v and so on.
this symptom is look like the ipad itself is trying to boot but failed, then i began to search if there is a short circuit across the board, alas there is no short at all and all voltages look like present and healthy except for the pulsing issue.
*the pulsing issue persists when the ipad is only powered by the battery. (with and without the power cable attached)
because i have no idea where to start diagnose further, i read in many forums that U2 tristar is likely to be the culprit, with that idea I tried to replace the tristar with a new one and the problem is of course still persist.
what i have already checked are
- the battery is known good
- charging port no problem (tried another one)
* no short circuit
- power button is good i think (i've tried jumper it from the on off from the power button connector and the problem still the same)
i think the real culprit will be U8100 which is the PMU because the PMU is responsible for power delivery to those component on the logicboard (right?) but im not sure because i don't have enough evidence yet to replace that PMU
or maybe the communications board (where the baseband chip located i suppose) can cause the issue?
Es esta una buena pregunta?