Samsung NP300E5A-A05ES doesn't start

[CasasElectronics]

Hello,
I've a the laptop of the title, the problem which has is that when you power it it starts but the only thing which works is the cooler fan at full speed and the power leds, there isn't response at screen (including VGA or HDMI) or sound.

The voltages seem to be present, and there aren't shorts on the motherboard.
I've seen that it could be a problem in the BIOS, but samsung doesn't give me the BIOS file and the schematic. The problem isn't in the graphics card because it hasn't a dedicated one.

I need help and I would be so grateful if you can help me.
Thanks a lot.

[bob_rf]

Re: Samsung NP300E5A-A05ES doesn't start

clear memory card contacts

[Techtiger]

Re: Samsung NP300E5A-A05ES doesn't start

Test the Voltage of each big Grsy Coils of the Mob and post it examples CPU CORE GFX ect with help of pic of MOB

[CasasElectronics]

Re: Samsung NP300E5A-A05ES doesn't start

I've cleared memory card contacts, but i have the same response. I cannot check all the voltages because i don't have schematic of the board.

[Techtiger]

Re: Samsung NP300E5A-A05ES doesn't start

if this your Mob come up with all voltages I have marked you can find similar schematic

[CasasElectronics]

Re: Samsung NP300E5A-A05ES doesn't start

These are the voltages i have readed, i also have reprogrammed the BIOS having the same response. There are 3 voltages of 0 near the processor that I think they would be bigger:

[mcplslg123]

Re: Samsung NP300E5A-A05ES doesn't start

These are the voltages i have readed, i also have reprogrammed the BIOS having the same response. There are 3 voltages of 0 near the processor that I think they would be bigger:

Yes these three coils are all part of vcc circuit-two of these coils likely to be vcc core and 1 of these might be gfxcore. You need to find out why vcc core is not generated. Check KBC pin for VR_ON signal and vcore ic pin voltages. can be 'coz of missing run voltage also.

[CasasElectronics]

Re: Samsung NP300E5A-A05ES doesn't start

Ok, i will find out that to see if I can locate the problem.
I have seen a thread in Facebook of the same laptop with the same problem, which was solved replacing the SPI memory to a new one, and reprogramming it.

[CasasElectronics]

Re: Samsung NP300E5A-A05ES doesn't start

I have replaced the SPI memory an reprogrammed the BIOS with the .bin of this laptop and i have the same response, at start i have fan 100% working and any response, i don't have response in the screen and with a external monitor the same result.
Also I've tested the power comsumption and i have 0.2A at 19.2V, i think that the starting cannot be completed.
The processor doesn't get hot and the only response i have is the power off when i press the power off button.

[piernov]

Re: Samsung NP300E5A-A05ES doesn't start

Missing CPU VCore is definitely an issue.
You didn't report the voltage for the RAM supply on the backside of the board.

[CasasElectronics]

Re: Samsung NP300E5A-A05ES doesn't start

I've been investigating the lost voltage and i've found that there are 4 mosfet which have it's VGS=0V. I've also checked the RAM voltage obtaining 0.25V.
I've checked the mosfet controller and I've found that I've correct supply values on the controller (VR_ON, activation pin is 3.03V, VDD supply pin is at 5V, VCCP also is at 5V)
There are two pins on the controller called PGOODG and PGOOD which would be high for a good operation but the controller puts them at 0V, bescause i've cutted the track on the board, having 3V by the external side and 0V by the side of the controller.
I'm thinking of buying a new one.

[piernov]

Re: Samsung NP300E5A-A05ES doesn't start

You have to worry about RAM supply voltage before worrying about CPU VCore.

[Lvsitano]

Re: Samsung NP300E5A-A05ES doesn't start

Usually there are those issues with NEC tokin present, but in your case you have tantulum caps. So it must be something serious.