Acer Nitro 5 EC_RSMRST# present, Missing SLP_S5#!!!

[Kooopa]

Hi! I'm diagnosing my Nitro 5 AN515-43 Mobo: FH50Q LA-J621P. I left it on sleep mode but when I came back It won't turn on. Power LED would turn on for a few seconds then off. no fan spin nor keyboard backlight.

So I tried the usual procedures first, power cycling and bios reset but non did the trick so I decided to delve deeper.

Nothing strikes as red flags aside from the dust. there's no history of any liquid being poured at it since I bought the thing, I've been real careful. Anyways.

I checked the usual rails +5VALW +3VALW even the 1.8VALW and 0.9VALW are present EC_RSMRST# is present and is at 1.8v after pressing the PWR BTN. I followed the power sequence and it led to SLP_S5#. I'm thinking somewhere on the RTC??? area is at fault but it's been a while since I last worked on a laptop as I've switched to Automotive Repair years ago so I feel like I'm on uncharted territory yet again. and any help is greatly appreciated!!

I probed around using continuity mode on my multi and the only thing I found is a 3 ohm path to ground on one side of some capacitors and the inductors surrounding the CPU and GPU area but I seem to remember there's a reason for it. aside from that nothing else, board looks brand new.

I've attached the schematic for anyone who wants to take a shot at it.

Thanks.

https://www.badcaps.net/forum/troubl...need-schematic

[Kooopa]

UPDATE!!!

I replaced the RTC crystal from another broken laptop with AMD chipset and now to it powers on completely but not posting / black-screen.

I checked +APU_CORE and it's at 1.025v RAM voltage is also present at 1.2V. I'm leading towards BIOS corruption

Unfortunately the chip is 1.8v and my cheap ch341a programmer doesn't do 1.8v so I ordered an adapter.

In the mean time can you guys suggest anything else to check? I'll try and check other avenues while I'm waiting for the adapter to arrive.

[mcplslg123]

PU502,pin6 voltage?
U4-pin 1-2-3 voltage?
UV45=voltage on all pins?
If you have a DSO,check LPC pins on SIO and SCL/SDA communication on ram slot.

[Kooopa]

Hi! mcplslg123 thank you for your query

I probed what you asked and here's the voltages

Pin 6 of PU502 = 2.549v
Pin 1,2,3 of U4 = 0.933

UV45
Pin 1 = 1.860v
Pin 2 = 1.860v
Pin 3 = 5.156v
Pin 4 = 0v
Pin 5 = GND
Pin 6 = 0v

Unfortunately I don't have a DSO, I'm still saving because I want to buy a decent one.

I also measured the resistance to GND of pins 4 and 6. measurements are climbing slowly probably because of the cap

Pins 4 = 14Kohm
Pin 5 = 17Kohm

I noticed that UV45 is what switches the enable signal for the GPU rails.

I may have goofed up and tried reading the ROM chip of the GPU without realizing that it's 1.8v, but I removed the chip from the board first before reading it and avoided sending 3.3V on a 1.8V rails. I can read the chip just fine using my ch341a but for some reason I cannot erase the chip as it keeps failing to write FF. that's when I touched the chip and noticed it's hotter than usual and that's when I realized I messed up.

Can this be the cause of no POST?? if so can I temporarily disable the dGPU so that I can test it? I'm trying to pull data from my NVMe drive and it would be great if I can get it to boot with the iGPU

thanks.

[mon2]

Which ROM? Yes, operating a 1v8 rated semiconductor @ 3v3 is deadly to the device. This rom may be the show stopper.

Review the enable signals for the GPU power path since pin #4 is @ 0v.

[Kooopa]

Hi! mon2 thank you for the input.

the ROM in question is UV49, I'm thinking EC is not sending the EN signals because it can't read the dGPU bios.

I checked 1.8VSDGPU_MAIN_EN and 1.8VSDGPU_MAIN_EN3V3 from QV7 and both are 0v

[mcplslg123]

Programming any eeprom with CH34 is a bad idea in my experience. Often it gives errors and sometimes it writes without error but still doesnt work. Invest in a better spi programmer like RT8209H/SVOD etc.
1.8VSDGPU_AON present?

[Kooopa]

Programming any eeprom with CH34 is a bad idea in my experience. Often it gives errors and sometimes it writes without error but still doesnt work. Invest in a better spi programmer like RT8209H/SVOD etc.
1.8VSDGPU_AON present?

I agree that the ch341a is a bit finicky, but this line of work is just my hobby and besides I rarely need it. if it doesn't work i can always program an MC to interface to the chip.

With that said, here comes the good news. I got tired of the dreaded 7 days shipping time of the adapter and decided to just build my adapter. and what do you know the Flash IC survived my stupid attempt to read it and what's more the earlier attempt to read it, produced a good working dump. so I flashed it again and I managed to get it to work and boot to windows.