Acer Nitro 5 FH52M LA-J891P no display

Hi everyone,

Acer Nitro motherboard FH52M LA-J891P Rev.. 1B
The laptop arrived with a short circuit on the main power supply line +19v
After measurements and a short circuit test it was discovered that PQZ2 (AON6962) and PQB11 was damaged. After removing it from the board, the short circuit on line disappeared.

once the components have been replaced the mainboard now starts but does not give any image on the screen.
the fans spin, the keyboard lights up but no image. if I put a USB stick with LED it doesn't flash. If I remove and insert the power supply I hear a beep. the battery has charged

I noticed that There is no voltage on PLG1 - +VCC_GT, the rest of the voltages on all coils are correct.
I tried swapping PUG1 with the other components on the board but the power doesn't come back +VCC_GT

any advice on what to try?
I haven't flashed the bios yet. It is possible that a corrupt bios does not activate +VCC_GT ?

sarino69 ha scritto:it was discovered that PQZ2 (AON6962) (..) was damaged.

Unfortunately, it seems that the CPU is most likely fried. I had a number of these boards in my workshop and all the time, when the upper part of PQZ1-PQZ4 was shorted, the CPU was damaged as well.

sarino69 ha scritto:There is no voltage on PLG1 - +VCC_GT

This voltage starts up as soon as the integrated graphic's drivers are loaded - in your case the OS does not start at all so the lack of +VCC_GT voltage is normal.

thanks so much for the explanation. so you think it is useless to load a new bios? Is there a way to check if the processor is dead? any measurements I can do?

sarino69 ha scritto:so you think it is useless to load a new bios?

It is always worth to try something which does not involve spending the money - BIOS reflash is one of these things. Please do not forget to transfer the original ME region.

sarino69 ha scritto: Is there a way to check if the processor is dead?

Unfortunately, there is no 100% certain method to confirm a CPU fault rather than replacing it with the known working one. All you can do is to measure the resistance to ground at VCC_CORE rails (of course after removing the faulty transistors). If the resistance is below 2Ω the CPU is faulty for sure.