Hello everyone,

An Asus s550cm (K56CM board) came turning on with a black screen, found that Nvidia GPU has been reflowed before, tried to reflow it but it didn't came, nothing is shorted on the board, everything rises except PL8003 (integrated graphics)

PL8005 rise to 1.1v then falls to 0.85v - 2.2ohm
PL8003 0v - 1.6ohm
PL8200 1.04v - 4.3ohm
PL8301 1.57v - 299ohm with memory - 483ohm without
PL8500 & PL8501 0.88v - ??ohm (not shorted)

I've followed this topic viewtopic.php?f=40&t=106442

Removed PJP8500 and PJP8501 as mentioned but the board turned on then off immediately within 0.5 seconds each time i press power button..

Removed PU8500 (NCP3218), same behavior, power cut in 0.5 sec
Removed U7001 (N14P-GE-OP-A2) from the board, now it turns on without a cut but still 0v at PL8003

Flashed the bios given in that topic in this link https://cloud.mail.ru/public/44pA/5tg3nJEC7

Now the board came on for 4 seconds then off cyclically, PL8003 now tries to rise (sometimes reaching 0.8v before power cut)

PL8005 behaves like 1.1v-0.85v-1.1v-power cut

Is it a problem with the flashed BIOS, ME or something ? or could it be something else ??

*edit: model number S550CB-CJ074H
MB model K56CM Rev 2.0 PN:60NB02D0-MB1000(200) S550CB

So, problem with something else, not discrete video

How to tell ?

The board started after removing the discrete chip but it didn't automatically switch on the integrated graphics (PL8003 still 0v)

Flashing this UMA BIOS https://cloud.mail.ru/public/44pA/5tg3nJEC7 given in this topic viewtopic.php?f=40&t=106442 made it start but only for 4 seconds and then it cuts off the power then on cyclically..

In those 4 seconds PL8003 is trying to rise (the last one to rise) whitch means RT8168B started to follow SVID commands for integrated graphics and switched to it..

Also, before the power cut I've noticed SVID's changes from RT8168B's to Core Voltage in PL8005 from 1.1v(start-up) to 0.85v(idle) and a rise to 0.9v~1.0v which is definitely a load on the CPU..

The board is starting up and tries to load but something is cutting off before an image appears..

Removing RAM stops the initialization and keeps the power without a cut, PL8005 1.1v and PL8003 0v

Tried multiple RAM's and removing Q7703 (discrete VRAM voltage) since I didn't remove them from the board - still no success

Noticed that there's no response to the power button while the board cycles on and off, PM_RSMRST# rise to 3.3v and keeps up till removing the charger..

I suspect the UMA BIOS, would someone offer a working/cleared ME UMA BIOS to try

Flashed CA UMA firmware and the board started..

PL8003 has 0.85v now, got initialized with caps lock/num lock working, screen light comes on but there's no image..

No image on external monitor too, I can adjust screen brightness using fn+f5/f6, screen light goes off by switching to external with fn+f8 and with ctrl+alt+del..

Tried a couple of firmwares, same problem

What could it be ? is it bios related or removing the dead nvidia chip from the board caused this ?

attached the bios file that enabled the integrated graphics power

Measurements on U7002 (SN74LVC1G08DCKR)

Pin1 (BUF_PLT_RST#) 3.32v
Pin2 (GPU_RST#_R) 3.32v
Pin3 (GND) 0v
Pin4 (DGPU_RST#) 3.32v
Pin5 (+3VSG) 3.32v

is this normal ?

disabling input on pin1(0v) or pin2(0v) to disable pin4(0v) and screen light goes off

You should try to disable discrete graphics in original bios via AMIBCP. Graphics chip uses pci-e interface, so, disable one of pci-e channels, probably it is 0; 0 device.

But, as I think, that board should start also with damaged video, as i remember, there are optimus technology, and lvds lines connected to pch, not video. Discrete video here - simply computing module, and will be used only when it's needed. Also, there are typical problem with these books, lcd cable, you should test it.


And needed to measure resistance on the lvds pairs.

Thanks for the tip, using AMIBCP made me enable integrated graphics in the original bios, screen lights on but nothing appeared, just like the CA UMA bios..
Can't find a setting to disable a pci-e channel but I've tried lots of different settings with no avail..



Tried another working screen, nothing..
Cable tested in diode mode, all pins are connected except pin14 (EDP_HPD) which I believe is not used (chips aren't soldered onboard and this pin doesn't go anywhere)..



EDID_CLK_PCH 10k
EDID_DAT_PCH 10k
LVDS_L0N_PCH 117.3k
LVDS_L0P_PCH 117.4k
LVDS_L1N_PCH 117.8k
LVDS_L1P_PCH 117.8k
LVDS_L2N_PCH 117.9k
LVDS_L2P_PCH 118.1k
LVDS_LCLKN_PCH 117.7k
LVDS_LCLKP_PCH 117.8k

Add to that, I've also tried disabling +3VSG/1.5VSG, set DGPU_RST# to 0v, set MFG_Mode to 0v (remove R2518), set GFX_CRB_DET to 0v (move R2517 to R2527), set BUF_PLT_RST# to 0v, set GPU_RST#_R to 0v

No luck at all !

So...
If you have BUF_PLT_RST# = 3V, it means that platform doesn't start. Graphics chip should start later.

Can you look about post codes?

wow, is that possible ? i have a fully working keyboard doesn't that means it started ?

i don't have a post card, tell me where to dig ?

Sorry, 3.3 for reset signal is normal

It's inverted signal and it's okey.

Try plug off LCD cable and start motherboard with external display, thru vga or hdmi.
All that you need to do is cut PJP8500 and PJP8501 and flash dump from the topic linked in your first message. And take away RTC battery for one minute to clean CMOS.

Да я затупил, исправил уже

Tried that but nothing comes through vga/hdmi..



That Bios didn't work for me, only by editing and setting (Primary Display from Auto to IGFX) and (Internal Graphics from Auto to Enabled) made it work like all other Bioses, board is on and fully initialized, screen is on but nothing displayed..

Even the original K56CM Discrete dump works after editing those settings..

Cutting PJP8500 and PJP8501 cuts the main DGPU power but doesn't cut other DGPU voltages (+3vsg/+1.5vsg/+1.8vsg) so I believe unsoldering the dead Nvidia chip was the main reason for this issue, the board thinks the chip is still there and awaiting for some signal from it and that signal is related to those vsg's..

It's very hard to find using only a boardview and no schematic in hand..

I need Schematic or high resolution images of UMA board

No schematic or images in that topic, also I've checked under the GPU and nothing found there..

I'm still looking for some high resolution images of the UMA board but can't find any image without the protection film covering half of the bottom side, could someone help ??

In this topic, not diagrams, but the procedure for disabling discrete graphics.

Using AMIBCP I've turned on (Play POST Sound) and flashed the bios, and the post sound played normally...

I've checked for resistance on the lvds pairs and it was normal, I've checked for voltage and here's the bad news !

With & without LCD screen:

EDID_CLK_PCH 3.3v
EDID_DAT_PCH 3.3v
LVDS_L0N_PCH 0v
LVDS_L0P_PCH 0v
LVDS_L1N_PCH 0v
LVDS_L1P_PCH 0v
LVDS_L2N_PCH 0v
LVDS_L2P_PCH 0v
LVDS_LCLKN_PCH 0v
LVDS_LCLKP_PCH 0v

+1.8VS_VCCT_LVD at L2604 = 1.74v
LVD_IBG at R2305 = 0v
LVD_IBG at R2306 = 0v

Now what ?? where should I dig ?

mohammedsf
Try to measure the resistance on the lines LVDS, EDID reads?
often there is a faulty loop of the matrix

Without LCD screen:


With LCD screen connected:
EDID_CLK_PCH 3.8K
EDID_DAT_PCH 3.8K
LVDS_L0N_PCH 19.5K
LVDS_L0P_PCH 19.5K
LVDS_L1N_PCH 19.6K
LVDS_L1P_PCH 19.6K
LVDS_L2N_PCH 19.6K
LVDS_L2P_PCH 19.6K
LVDS_LCLKN_PCH 19.6K
LVDS_LCLKP_PCH 19.6K


I know they are data lines but no oscillator in hand for that... I can measure voltages only and I've seen a slight drop and rise 10mv~50mv (it might be a movement) for one second within 2~3 seconds from pressing the power button in both EDID_CLK_PCH & EDID_DAT_PCH signals, is that a sign of data movement ?


It's almost impossible to find a replacement in my city and it would take 40~60 days to arrive from outboard.. It's very desperate.. I've checked the flex cable using the tester in diode mode, all the lines rang except Pin 14 (EDP_HPD) but i didn't care because EDP_HPD isn't used, all components aren't soldered on the board and the signal doesn't go anywhere..

Are those LVDS signals rise ONLY when a good screen is connected using 100% working flex cable ? please clear this point..

Could it be a setting in the bios to enable lvds ?

I've missed with lots of settings with no avail, here are some:

Disable PEG..
Disable PEG Link..
Disable fast PEG init..
set IGFX as Primary Display..
set Internal Graphics as always enabled..
tried muxed & non muxed & HPD only iGPU ports..
tried setting LFP & LFP2 as primary iGFX boot display..
tried to set 1366x768LVDS as LCD panel type rather than the VBIOS Default..
lowering all PCIE speeds to Gen1 speed..
Disable PCIE root ports 1,2,3,4,5,6,7,8..

Adding measurements on screen side:

VBL = 19.08v
BL_EN = 3.27v
PWM = 0.34v (for a second it rise to 3.3v on start then fall to 0.34v)
RXCP = 0v
RXCN = 0v
RX2P = 0v
RX2N = 0v
RX1P = 0v
RX1N = 0v
RX0P = 0v
RX0N = 0v
VCC = 3.28v
PVDD = 3.28v

I've double checked lcd cable, all RX lines are connected to the board...

After converting to UMA at hardware level and after modifying the Bios and vBios to force iGPU on, signals from iGPU to PCH where found on FDI lines but still no LVDS output so it was clear that LVDS lines are burned out..

There is no way to replace BGA chips in my city so the laptop was given without repair.. I'll close this topic..

From the experiment, here are the elements related to UMA conversion:

PCB ID Select:
R2438 = N/A & R2437 = 10k ID0 (Low=DIS)
R2435 = N/A & R2436 = 10k ID1 (Low=DIS)
R2429 = N/A & R2430 = 10k ID2 (Low=DIS)
* ID selection information for UMA wasn't found

DIS to UMA:
Cut PJP8500 & PJP8501 (dGPU power)
Remove R7709 & R7710 & Q7701 (3VSG)
Remove Q7703 (1.5VSG)
Remove RN2102 (PEG PCIE PCH Clocks)
Remove Q2101 (dGPU power ok signal)
Remove Q7704 (+PEX VDD)
Remove PU8500 (dGPU controller)
Remove U7003 & Q7001 & R7022 (dGPU power on and enable signal)
Remove U7002 (dGPU reset signal)
Remove R7022 (dGPU power EN signal)
Move R7021 -> R2409 (dGPU power EN# correct)
Add R2514 1k (dGPU power ok signal correct)

dGPU Present Signal:
R2517 10k & R2527 N/A = High DIS
R2517 N/A & R2527 10k = Low UMA

PCIE-x16 port Enable/Disable = R0301 (24.9ohm=Enable, remove=Disable)
PCIE-x16 Lane Reversal = R0502 (1k = reverse/dGPU present)

Attached KM56CA UMA Photos