Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

[BlkMolly]

Hello,
I hope you are all well.

I have an Acer Nitro AN15-51 (Board LA-E911P) that will not display anything no BIOS nothing.

Once power (from AC) is applied, keyboard lights up, fans spin for about 5 sec, CPU, GPU, and PCH start warming up, all seems to start ok, however no display no cap key acknowledgement and no USB activity just USB power.

The below IC's are of concern to me as there temps are high

UL2 (LAN/SD controller IC) gets hot
UX1 (LCD Power dis switch) gets very hot even if LCD is unplugged
UX1 seems to have a short between pins 1&5 and about 4ohms from those pins to GND.

I'm hoping to get some time tomorrow to de-solder UX1 and test again, in the mean time is there anything else I should be looking for and why would UL2 been so hot?

Any suggestions would be greatly appreciated, as I'm stuck with this one.

Thank you.

[BlkMolly]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Update:

I have removed:

UX1 (LCD PWR_DIS SWITCH) As the IC gets very hot
even without LCD connected, seems to be a short from pin 1 to 5 on IC.

I have tested:

1. RSMRST line @ pin 100 UB1 (EC) = High/Good

2.POWER GOOD/OK Lines:

2A. VR_PWRGD = 3.43v
2B. ALL_GPWRGD = 1.91v ?
2C. H_CPUPWRGD = 1.10v ?
2D. DRAMRST = 0v (should this be around 1.3v?)

3. Two main voltages still missing (maybe more)
3A. +VCC_GT (Resistance to GND = 7ohms)
3B. +VCC_CORE (Resistance to GND = 3.5ohms)


UL2 (SD & LAN CONTRL) Still running very hot, will need to de-solder and test.

My suspicions:
BIOS corruption or PCH damaged, not to sure about UL2 maybe it got struck by lightning ha ha...?

Anything else I could try, please let me know as I'm stuck and could be casing my tail.

Big shout out to highpulse and adiedkhaz for the Reset signal test sheet !! (https://www.badcaps.net/forum/showth...light=VCC_CORE)

[mcplslg123]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Dramrst# should be 1.2v for dete & 1.35v for ddr3-L. Without ram being reset,gfx core will not rise.

[BlkMolly]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Update:

I have back tracked a few startup steps and found that the PLT_RST signal is not coming out of the PCH.
I have checked as close to the PCH as I could to make sure no PCB traces are damaged however still a no go, so seems to be a faulty PCH?

I could attempt a PCH reflow ?

Any advice would be welcome

Many thanks All.

[mcplslg123]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Dont reflow the soc. You may loose whatever chances you have to fix it. Check why DRAMRST# is pulled low. PLTRST# will come almost at the end of posting and when ram is not being reset by the system where is the question of PLTRST# rising?

[BlkMolly]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Update:

I have Checked DRANRST line and to the best of my knowledge/ability I think its ok.
I checked the pull up resistor at RD6 and found the value to be 464Ω (see attached picture) this is within spec, so I'm still stuck.

I guess I need to step back in the startup procedure and see if other lines/signals are present.

Thanks for the info mcplslg123 much appreciated

[mcplslg123]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Was 1.2V present on both sides of RD6??

[BlkMolly]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

On power up of board (power button pressed) 1.2v is present at pin 2 RD6, The other side of RD6 pin 1 shows 125mv suggesting the line is being pulled down.

The only oddity's that I have found is H_CPUPWRGD is only 1.1v (is this still regarded as high) and isn't H_CPUPWRGD suppose to be high after DRANRST is high, in the start up sequence? (this is with my limited experience on board level repair so I maybe way off)


Some original faults I had not mentioned with this board were:

PQ303 MOSFET shorted StoD now replaced.
UO1 getting a bit to warm even without HDD connected.

Oh..also I removed UL2 as I thought it maybe causing issue as it was getting very hot (too hot to touch) still not joy.

Just thought the above may help, in case those issues have caused the current problems.

Thanks for the input mcplslg123.

[mcplslg123]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

H_CPUPWRGD at 1.1V is good. So DRAMRST# is pulled low and thats a problem. Ram reset is done by processor. It could be bios issue so i'll strongly suggest to flash bios first and the new bios should be known good+me cleaned. You can make a request in bios section while posting your original bios backup there. Experts there are very co-operative and will respond to your request.

[BlkMolly]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

Hello mcplslg123 and All,

I have found that someone in the forum has already uploaded a BIOS for my board (see link below) and there results are encouraging, so I attempted to flash the BIOS.

My steps in flashing the BIOS:
1. Used a CH341A mini programmer and dumped the BIOS twice.
2. Compared the two dumps (the same).
3. Downloaded the the BIOS bin from (https://www.badcaps.net/forum/showth...+LA-E911P+BIOS).
4. Uploaded the BIOS .bin to the chip and verified the upload.
5. Powered up the board with the same results, no DRAMRST (signal being held low)

I'm thinking I could try a new BIOS chip just to rule that out, however I assume with the dumps and the upload of the BIOS .bin the chip is ok?

I have attached the BIOS .bins to this message.

If anyone is willing to go over my findings and or has any other ideas that would be greatly appreciated

Thanks again for the guidance and info.

[mcplslg123]

Re: Acer Nitro AN15-51 (Board LA-E911P) Powers on No display

I've no more ideas and beleive the SOC is faulty since you confirm ram stick to be good and proven bios flashed.