HP Probook 4540S No Display

[battery.12v]

Hello Guys, HP Probook 4540s Discrete, No Display, Caps lock blink 5 times ,PLTRST# is high and All Voltages are OK except GFXCore and i think thats ok, as it wont rise up before POST, any idea or guidance ? ...
Flashed Bios but nothing changed, Changed CPU also but no luck

[stingerchamp]

Re: HP Probook 4540S No Display

You need oscilloscope to check PCH crystal xtal is ok or not , 24 MHz clock coming

[battery.12v]

Re: HP Probook 4540S No Display

You need oscilloscope to check PCH crystal xtal is ok or not , 24 MHz clock coming

Sorry but i dont have oscilloscope, i tried to convert it from Dis to UMA but same problem 5 times blinking

[stingerchamp]

Re: HP Probook 4540S No Display

Check bios pin 1 chip select

But with DSO only

CPU is dead if CS is ok and pltrst#is 3.3v or high

[battery.12v]

Re: HP Probook 4540S No Display

Check bios pin 1 chip select

But with DSO only

CPU is dead if CS is ok and pltrst#is 3.3v or high

do you mean by DSO a digital oscilloscope ?
i changed CPU with three different ones and same problem
PLTRST# is 3.3v
CS is 3.3V i dont have OScilloscope
could Someone provide me with a trusted working bios

[stingerchamp]

Re: HP Probook 4540S No Display

Yes digital storage scilloscope

PCH communicates with bios chip not ec bios

With chip select C's pin 1

First with oscilloscope check crystal is having frequency or not at 10x probe

and clock is ok or not

Pltrst# means PCH is ok at power level only

[battery.12v]

Re: HP Probook 4540S No Display

Yes digital storage scilloscope

PCH communicates with bios chip not ec bios

With chip select C's pin 1

First with oscilloscope check crystal is having frequency or not at 10x probe

and clock is ok or not

Pltrst# means PCH is ok at power level only

as i dont have an oscilloscope, can you tell me what are the consequences of a working CRystal Clock VS non Working one, as i can just replace it blindly

[stingerchamp]

Re: HP Probook 4540S No Display

To make sure ram section is ok and
CPU is sending dramrst# signal , check dramrst#
±++++++++++++++++++++++++++++++++++++++
Rtc section 32 khz clock is necessary for imp PCH communication

CMOS cell provides 3.3v supply to crystal 32 khz oscillator , here I am talking about in general

In new motherboards now more data hunger devices so

PCH has many oscillator working inside it , PCH has blue clock 14mhz , 24mhz etc. In schematic it is written as xtal in ,xtal out 4 legs Epson body ic

PCH gets this clock signal and boost its frequency to generate many frequency signals for audio, HDD etc
Detail is boring lol

PCH communicates with sio
Sio has ec bios which it reads for instructions to process and run diff device etc

Without crystal oscillator laptop will not work or no display
as no PCH communication, you flash bios or not does not matter if no clock

Without CMOS battery or cell , laptop will start and function but not in normal way

[battery.12v]

Re: HP Probook 4540S No Display

To make sure ram section is ok and
CPU is sending dramrst# signal , check dramrst#
±++++++++++++++++++++++++++++++++++++++
Rtc section 32 khz clock is necessary for imp PCH communication

CMOS cell provides 3.3v supply to crystal 32 khz oscillator , here I am talking about in general

In new motherboards now more data hunger devices so

PCH has many oscillator working inside it , PCH has blue clock 14mhz , 24mhz etc. In schematic it is written as xtal in ,xtal out 4 legs Epson body ic

PCH gets this clock signal and boost its frequency to generate many frequency signals for audio, HDD etc
Detail is boring lol

PCH communicates with sio
Sio has ec bios which it reads for instructions to process and run diff device etc

Without crystal oscillator laptop will not work or no display
as no PCH communication, you flash bios or not does not matter if no clock

Without CMOS battery or cell , laptop will start and function but not in normal way

DramRST# is 1.53V so its okay if im not wrong
should i change the PCH crystal ?

[stingerchamp]

Re: HP Probook 4540S No Display

Dram reset is ok ,PCH is ok as pltrst# is ok
Now comes bios check

At pin 8 bios 3.3v and some voltage on bios C's

If this is ok means everything is ok except gfx

Have you checked flashing EC bios
and PCH bios

To check bios is communicating we need clock signal on xtal crystal oscillator

Since we don't have oscilloscope
just check pin 1 of bios chip of PCH bios (main bios located near PCH)

If ok

Programme the KBC using vertyanov or svod if KBC is programmable

5 beep issue will get resolved

[battery.12v]

Re: HP Probook 4540S No Display

Dram reset is ok ,PCH is ok as pltrst# is ok
Now comes bios check

At pin 8 bios 3.3v and some voltage on bios C's

If this is ok means everything is ok except gfx

Have you checked flashing EC bios
and PCH bios

To check bios is communicating we need clock signal on xtal crystal oscillator

Since we don't have oscilloscope
just check pin 1 of bios chip of PCH bios (main bios located near PCH)

If ok

Programme the KBC using vertyanov or svod if KBC is programmable

5 beep issue will get resolved

i appreciate your support bro
i flashed bios but no luck and KBC is not PRogrammable
3.3V is present in pin 8 of Bios Chip

[stingerchamp]

Re: HP Probook 4540S No Display

Check CPU core voltage generating when on

Check vr-on signal

CPU is ok if core voltage ok


Can you make this Uma from discrete

[battery.12v]

Re: HP Probook 4540S No Display

Check CPU core voltage generating when on

Check vr-on signal

CPU is ok if core voltage ok


Can you make this Uma from discrete

CPu Vcore is 1.1V
VGate is 3.3V
yes i converted it to UMA by removing Coil but Same PRoblem

[stingerchamp]

Re: HP Probook 4540S No Display

Check following signals

Dram_pwgood
Dram_powerok
Imvp pwrgood
CPU pwgd
Vr_on from kbc
Ck_pwgd. Clock


Do you have schematic?

When you check crystal oscillator
Remove it it should not beep with each other pins

Change 24mhz crystal near PCH

Check 1.05 PCH supply just in case before removing

If CPU core voltage is ok

Last step check hwpg or
All sys power good

When PCH receive EC power ok signal and
When CPU gets dram power ok and CPU pwrgood and pltrst # from PCH, considering clock is ok then PCH will enable chip select pin of main bios and CPU will start interfacing with bios


I am not an expert but sharing what I know
My full support is to save your motherboard

Your PCH is ok
Your CPU is ok
Your KBC is getting ref clock of PCH at LPC ?



For GPU , discrete to Uma

First make sure you removed resistor which tells graphic card is present

Then remove coil

[battery.12v]

Re: HP Probook 4540S No Display

Check following signals

Dram_pwgood
Dram_powerok
Imvp pwrgood
CPU pwgd
Vr_on from kbc
Ck_pwgd. Clock


Do you have schematic?

When you check crystal oscillator
Remove it it should not beep with each other pins

Change 24mhz crystal near PCH

Check 1.05 PCH supply just in case before removing

If CPU core voltage is ok

Last step check hwpg or
All sys power good

When PCH receive EC power ok signal and
When CPU gets dram power ok and CPU pwrgood and pltrst # from PCH, considering clock is ok then PCH will enable chip select pin of main bios and CPU will start interfacing with bios


I am not an expert but sharing what I know
My full support is to save your motherboard

Your PCH is ok
Your CPU is ok
Your KBC is getting ref clock of PCH at LPC ?



For GPU , discrete to Uma

First make sure you removed resistor which tells graphic card is present

Then remove coil

CPu is ok, 25Mhz Crystal PCH is ok, Pltrst# is ok, All SystemPwGood is Ok, DramRSt# is ok, Cpu Vcore is ok, flashed Bios three times and no luck, changed Bios chip no luck

inserted a Debug Post Card and it gives me just 0

conserning UMA conversion all guides just instruct to remove only Coil

[stingerchamp]

Re: HP Probook 4540S No Display

If PCH is getting same signal that GPU is present
It will not switch display to lvds

If you have schematic,

You will sea board_id or vga_id or vram_id table

To convert to Uma

You need to change board id according to table

To change board id it will ask to remove or shift resistor to another place so that PCH gets signal that GPU is not available

It can be high logic 3.3v pull up or low pull down ground


After this if you remove coil PCH will shift display but it depends on board to board


In old board we also had to change clock and data lines for lvds to pch



Post card I do not have experience

But reset light will turn on and off one time

How are you measuring signals if you don't have schematic

[battery.12v]

Re: HP Probook 4540S No Display

If PCH is getting same signal that GPU is present
It will not switch display to lvds

If you have schematic,

You will sea board_id or vga_id or vram_id table

To convert to Uma

You need to change board id according to table

To change board id it will ask to remove or shift resistor to another place so that PCH gets signal that GPU is not available

It can be high logic 3.3v pull up or low pull down ground


After this if you remove coil PCH will shift display but it depends on board to board


In old board we also had to change clock and data lines for lvds to pch



Post card I do not have experience

But reset light will turn on and off one time

How are you measuring signals if you don't have schematic

this is the schematic

[battery.12v]

Re: HP Probook 4540S No Display

this is the schematic

Client Took his laptop unfortunatly

[stingerchamp]

Re: HP Probook 4540S No Display

Oh

Too late I guess

But anyhow

Do you want to get knowledge how to convert any laptop to uma

[lapfix]

Re: HP Probook 4540S No Display

Oh

Too late I guess

But anyhow

Do you want to get knowledge how to convert any laptop to uma

Perfect analysing , YES for all type of knowledge