LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

[spleenharvester]

Hi all.

UMA version of LA-8241P here. System powers up with 7 beeps, which is usually a CPU error. I've tested the CPU and RAM in another known working LA-8241P and they are fine. (I can also use this board for comparison readings if need be).

My findings are that +VCC_GFXCORE_AXG = 0V but does not appear to be shorted at PL704. On the known good board this voltage is 0.8V. +1.0VGS/+VGA_PCIEP also appears to be 0V, but given this board is the UMA version I'm unsure if these should be present?

Here are some other readings I've taken of various CPU voltage and others suggested in a similar post. Any ideas?

VCC_CORE = 1.1V
VCCSA = 1.05V
VCCP = 0.8V
+1.5V_CPU_VDDQ = 1.5V
+1.8VS_VCCPLL = 1.8V
+1.5V = 1.5V
+1.5VS = 1.5V
+VCC_GFXCORE_AXG = 0V, should be 0.8V

+3V_PCH and PCH surface cap = both 3.3V

PM_DRAM_PWRGD = 3.3V
VDDPWRGOOD = 1.5V
PCH_PWROK, SYS_PWROK leg of UC1 (as I cannot find components on individual rails) = 3.3V

BUFO_CPU_RST# = 1.05V
PLT_RST = 3V
+3VALW = 3.3V

PJP804 (+VGA_PCIEP/+1.0VGS) = 0V

[spleenharvester]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

So I've taken some more readings (attached photo) and I suspect PU701 is blown based on the fact that it's getting full input and giving no high or low-drive signals - are there any other scenarios through which this could occur?

[caspian]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

yes, the PWM input may be incorrect. check it using an oscilloscope.

[spleenharvester]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

Thanks - unfortunately no oscilloscope with me at the moment - I assume there's no other way to check besides replacing either PU701 or PU700 (NCP6132BMNR2G)? I did notice that the PWMA signal was 2V on this board but 0.35V on the working board actually - does this help at all? EDIT I think this was a bad reading, now getting 2V from good board as well. A post here also suggests these input voltages for NCP5911MNTBG are OK

Also other readings from the 'good' board for anyone else with the same issue:

DRVL (GFX_LG) = 4.5V
DRVH (GFX_HG) = 1.35V
GFX_SW = 0.9V

All other voltages were same as in the previous screenshot.

[caspian]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

how much voltage is on B+ on the healthy mainboard?

[spleenharvester]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

how much voltage is on B+ on the healthy mainboard?

9V from a tested working battery both when powered off and on - same on the 7 beeps board.

[spleenharvester]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

In this thread: https://www.badcaps.net/forum/showth...id=8&styleid=7 they have literally the same problem I do with a different board and a BIOS flash fixed it. Is it worth transplanting UH6 ('SPI ROM FOR ME, 4MByte') and UH2 ('SPI ROM FOR WIN8, 2MByte') from a scrap board to this board (I don't have a chip flasher)?

[caspian]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

yes, it worth trying. but it may lead to damaging the healthy mainboard if the two ICs get damaged. A programmer is a must in laptop repairing. It is recommended testing the laptop using the AC adapter.

[Th3_uN1Qu3]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

^^ I second that. If you have an old PC with a parallel port available, i can send you a schematic and board layout of the simplest self-powered programmer you can make, i have been using it for several years already. You only need scrap parts and you can make the PCB yourself at home, it is single sided.

[spleenharvester]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

Fortunately, both of my working (read: POSTing) boards are scrap anyway due to one having a knackered dGPU and one having a mangled LVDS connector I'll definitely stick an SPI flasher in my shopping cart tho!

[dellxps15]

Re: LA-8241P - 7 beeps, missing +VCC_GFXCORE_AXG

got a 17ich alienware with 7 beeps. ofcourse flashing bios back doesnt help.

but in my case no vcc core, while u have that.

tryed another cpu ?

edit: try also remove power, remove cmos battery and keep power botton pressed for some 10-20 seconds. then try put back cmon and psu and start it. still no gfx core?

ps: wait about also 80 seconds when poweered on and see if something changes.