Hp Spectre x360 DAY0DMB2AA0 black screen

[reset1986]

hi, I have this hp that had a PU18 ic that overheated and did not turn on, this managed the ram, replaced the pu18 ic and now the pc turns on, the fan runs but I have a black screen, measured the voltages I miss + VIN_VCCGT on PL21, this is managed by pu12 and pq13

pu12
pin 1 4.7v
pin 2 2V
pin 3 4.7V
pin 4 4.8
pin 5/6/7/8 0V

who can help me? Thank you

[Sephir0th]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

It's No issue when you can't measure VCCGT with your Multimeter. It's Normal to Not be present without load.
Checked all coils for Short or asking other way around, all other voltages are Coming Up?
Tested With known working HP charger of correct wattage and known working RAM?

[ktmmotocross]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

"PU18 ic that overheated and did not turn on, this managed the ram"

bad news for ram chips

[reset1986]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

thanks on the other hand, no short coils, I have the right voltages, only vccgt is missing
The RAM are welded, after the seat of the pu18 now I have 1.30v, with the faulty ic the car did not turn on

[ktmmotocross]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

rams are very fragile to bad voltage

[reset1986]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

It's No issue when you can't measure VCCGT with your Multimeter. It's Normal to Not be present without load.
Checked all coils for Short or asking other way around, all other voltages are Coming Up?
Tested With known working HP charger of correct wattage and known working RAM?

"PU18 ic that overheated and did not turn on, this managed the ram"

bad news for ram chips

rams are very fragile to bad voltage

i did a reflow on the rams, still black screen, the rams seem to work,
vcc ram 1.30v 78ohm,
vccgt 0v 4ohm
vcore 0.90v. 4ohm

it may be that there is no communication between ram and cpu?

[ktmmotocross]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

when ram chips goes bad by bad voltage reflow/reball dont help

[mcplslg123]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

VCCGT -you cant measure with multimeter. Still you can put your probe on this coil while powering on and there might be a slight deflection on your multimeter. that will prove there is nothing wrong in VCCGT . This signal comes at the last stage of power sequence and at the time of posting. I'll strongly suggest to flash bios first.

[mcplslg123]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

i did a reflow on the rams, still black screen, the rams seem to work,
vcc ram 1.30v 78ohm,
vccgt 0v 4ohm
vcore 0.90v. 4ohm

it may be that there is no communication between ram and cpu?

To check communication between cpu and ram, you can check SMBUS DATA/CLOCK on ram slot. If present, communication is very likely ok. You need DSO to be 100% sure but presence of voltage on those pins is almost a sure sign of communication ok between ram and cpu.

[reset1986]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

To check communication between cpu and ram, you can check SMBUS DATA/CLOCK on ram slot. If present, communication is very likely ok. You need DSO to be 100% sure but presence of voltage on those pins is almost a sure sign of communication ok between ram and cpu.

ok, I had tried to flash the bios, I extracted the 8 mb platform 0804F file on the hp site, still black screen, I will try the ram signals you suggested if there are voltages

[reset1986]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

VCCGT -you cant measure with multimeter. Still you can put your probe on this coil while powering on and there might be a slight deflection on your multimeter. that will prove there is nothing wrong in VCCGT . This signal comes at the last stage of power sequence and at the time of posting. I'll strongly suggest to flash bios first.

i measured some ram points, there seems to be communication with cpu, 0.6v,
i did a reflow on the cpu but still black screen, other ideas on what it could be?

[Sephir0th]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

Why did you do that?! You have risked an irreparable damage to the CPU, If it isn't already dead...

Till this Point it was possible it is Just a Bad RAM Chip. Now it could be a "no fix" at all...

[mcplslg123]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

You reflowed the cpu with hot air gun or Bga machine?? If it is hot air gun being used, there is high chance of cpu itself getting damaged. However, with bga machine reflow with correct profile, cpu will not be damaged.

[reset1986]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

You reflowed the cpu with hot air gun or Bga machine?? If it is hot air gun being used, there is high chance of cpu itself getting damaged. However, with bga machine reflow with correct profile, cpu will not be damaged.

I have been reballing for years, I use a ht r490, correct profile, 225 degree recast, the cpu still works but I have not solved the black screen problem
if i desalt one ram chip at a time can it work with only one chip?

the ram ic on the motherboard are 2

[mcplslg123]

Re: Hp Spectre x360 DAY0DMB2AA0 black screen

Hmm. Not sure it will work or not after desoldering one of those 2 ram chips. Never done that before.