dead Lenovo ideapad 320-15IKB

[bert-bert]

Hello,

I have a Lenovo ideapad 320-15IKB. (DG42A DG52A NMB244 Rev:1.0 PN:5B20N96152 The board has an Intel Core i5 7th gen CPU.)

I connect the power supply, have 20V at some ceramic capacitors near the coils on the picture, but 0V on any coil. When measuring the resistance between the coils and ground, PL401 measures 0R. All the other coils measure at least 10R.
PU401 is a Silergy SY8286BRAC as far as I see.

What shall I do next? Shall I measure the exact resistance between some parts, e.g. capacitors or chips to ground? I have a 6 1/2 digit DMM, but have not used it up to now for this mainboard. Shall I inject voltage, I have a thermal camera and regulated laboratory power supply at hand. Shall I replace PU401?

thank you in advance!

[SMDFlea]

Looks like a burn mark or some liquid spill just to the right of PJ405. There`s a schematic (NM-B242) & boardview (NM-B244) here - https://www.badcaps.net/forum/troubl...1-0-schematic?

[bert-bert]

thank you!

To me it looks like remains of flux from manufacturing. Is this possible? There's PU1402 on the other side of the board there where there is this dirt. But PU1402 looks nice.

Seems PU401 and PL401 are for the 3.3V rail. I guess I shall unsolder PJ402, to see if the short is on the upper or on the lower side of PJ402. And if the short is in PU401, I probably shall replace PU401, and if the short is not in PU401 it will get difficult.

I'll unsolder PJ402.

[bert-bert]

I unsoldered PJ402. And the voltage regulator is not shorted. It delivers 3.4V.

I also unsoldered J7 for the PCH. And the PCH is shorted to ground with 0R5. Is this ok, or is this defective? Is this a defective CPU? I'll give up on repairing this board then.

The other side of J7 is shorted to ground with 1R5. I can investigate further there.

[bert-bert]

And just a moment ago I also unsoldered PJ502 and PJ510. Every part of these wires is shorted to ground with below 1 Ohm. It must have been an error that I just measured 1,5 Ohm. Now I measure below 1 Ohm. Just the voltage regulator works at 3.4V. There must have been an overvoltage, and now everything is shorted, don't you think so?

Please confirm that I shall give up working on this dead board.

[mcplslg123]

Seems like shorted PCH-so you need to replace SOC ultimately.Else give up.

[bert-bert]

thank you mcplslg123 for confirming that I shall give up reparing this dead laptop!

I do not have the skills to replace the CPU.