Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

[LaPCon_IT]

Hi people,

Ideapad 130-15IKB
LA-G202P
CPU: i5 8250U

The laptop turns on without picture. All voltages are present except +VCCGT. Probably POST not starting because current stays around 300mA. I've checked resistance and voltages:

PL602 - 28ohm - 1.0 VALWP - 1.04V present
PL502 - 231ohm - 1.2VP - 1.2V
PLA1 - 17ohm - VCCSA - 1.03V
PLZ1 - 4ohm - VCCCORE - 0.84V
PLZ2 - 4ohm - VCCCORE - 0.84V
PLG1 - 7ohm - VCCGT - 0V

The VCCGT comes from PUG1 (RT9610CGQW). Signals are:
EN-5V,
PHASE-0V,
UGATE-0V,
BOOT-4,7V,
PWM-2.5V,
LGATE-0V,
VCC_GT-5V

PWM signal comes from PUZ1 (RT3602AE). All mosfets are good. I have noticed that PWMs on PUZ2 and PUZ3 (responsible for VCCCORE) are 0.22V, and also comes from PUZ1.

I have already replaced PUZ1, PUG1,reprogrammed BIOS and EC. No change and no ideas, what to do next. Oscillators 32kHz and 25MHz are working. The RSMRST is high so I assumed that EC is good.

[Sephir0th]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Usually no point to troubleshoot +VCC_GT, since the voltage appears only under load, so the mess there was likely for nothing.

Same for RSMRST# when the board reaches the late sequence.

I'd stay at BIOS instead, and check whether PLT_RST# and DRAMRST# are present.

You might want to restore all the firmware you have played with so far, to have a good start point.

[LaPCon_IT]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Thanks Sephir0th for the answer.

About bios: I used latest available from Lenovo website. After replacing ICs I have returned to original bios file.

DRAMRST# is low all the time, about 76mV. PLTRST# is 3.3V. I hope I've found the right place to measure it (picture).

[Sephir0th]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Yeah, that's fine but also check at Y-Pin for sanity. DRAMRST# staying low is actually a bad thing. Please double-check.

RAM is known good?

[LaPCon_IT]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Y-pin is also 3.3v. RAM is onboard. But there is one DIMM slot. I used good RAM but no effect.

I've checked DRAMRST# with oscilloscope. It stays low all the time.

[Sephir0th]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

If BIOS was ruled out for sure be sure, i'm afraid to share we're likely dealing with a dead CPU/PCH here.

[LaPCon_IT]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

OK, so I have another donor for my collection. Thanks for help.

Does always low DRAMRST# mean faulty CPU/PCH? Could you explain it more?

[rediii]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

OK, so I have another donor for my collection. Thanks for help.

Does always low DRAMRST# mean faulty CPU/PCH? Could you explain it more?

it usually means that either your soc/cpu or the firmware is faulty (there are exceptions...). it's one of the last rails that starts in the power sequence (block diagram).

[mcplslg123]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

I'll bet for a faulty onboard ram here. If you have access to schematic and boardview, disbale the onboard ram and put up a known good ram stick. Lenovo and asus are notorious for onbaord ram issues.

[rediii]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

I'll bet for a faulty onboard ram here. If you have access to schematic and boardview, disbale the onboard ram and put up a known good ram stick. Lenovo and asus are notorious for onbaord ram issues.

ah sure, there is soldered ram. this is the best advice! the amps read are a big clue for ram issue.

[LaPCon_IT]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Hi, sorry for the absence. There is only schematic available, so finding those resistors is imposible for me.

[mcplslg123]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Yes, no point trying to disable ram under darkness. Its impossible to do without boardview.

[fauzanmint]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

we can disable ram on board by bios modified.

[LaPCon_IT]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

we can disable ram on board by bios modified.

Could you guide me, how to do it?

[tahc81]

Re: Ideapad 130-15IKB, LA-G202P rev.1.0 no picture, +VCCGT

Could you guide me, how to do it?

Serach on Google for "spd bios onboard memory removal"