Is this regulator on the 5v standby coming from psu?
is pin 2 dead short to the ground like zero ohm or it's more than zero ohm like 5 ohms or more?

multimeter with good range and going over all chips powered from 3.3V measuring VCC to VDD in resistance mode as close to those chips as possible. With any luck you will get the idea where resistance is lowest.
Another option thermal camera and injecting voltage on 3.3V rail slowly going up and looking whats going warm, again with luck you might get by with a finger instead of camera

Karbist wrote on 2023-06-13, 20:33:

Is this regulator on the 5v standby coming from psu?
is pin 2 dead short to the ground like zero ohm or it's more than zero ohm like 5 ohms or more?

Yes it's the 5V stanbdby coming from the PSU.
Computer off I have 5V on Vcc and I have 2,6V on Vout (normally I should have 3.3V ?) and the AMS1117 is very hot. On the ground I have a 0 ohm (R126).
After few seconds, the motherboard tries to light up but without success...

rasz_pl wrote on 2023-06-13, 21:37:

multimeter with good range and going over all chips powered from 3.3V measuring VCC to VDD in resistance mode as close to those chips as possible. With any luck you will get the idea where resistance is lowest.
Another option thermal camera and injecting voltage on 3.3V rail slowly going up and looking whats going warm, again with luck you might get by with a finger instead of camera

Computer off the AMS1117 is very hot. I’ll check on the other chipset
After few seconds, the motherboard tries to light up but without success...

that standby 3.3v goes directly to the south bridge chipset, put the ams1117 back in the board and put your finger on the south bridge chipset, if one spot on the chip gets hots, it's dead.

Karbist wrote on 2023-06-14, 06:22:

that standby 3.3v goes directly to the south bridge chipset, put the ams1117 back in the board and put your finger on the south bridge chipset, if one spot on the chip gets hots, it's dead.

The southbridge is the chipset between the PCI port and the battery ?

Yes.

Karbist wrote on 2023-06-14, 07:43:

Yes.
ab-bp6.jpg

Tested and the southbridge is not hot.

well check the other chips like the I/O chip on top of pci slots. you can also put your hand on the back of the board and feel what area is getting warm.

rasz_pl wrote on 2023-06-13, 21:37:

multimeter with good range and going over all chips powered from 3.3V measuring VCC to VDD in resistance mode as close to those chips as possible. With any luck you will get the idea where resistance is lowest.
Another option thermal camera and injecting voltage on 3.3V rail slowly going up and looking whats going warm, again with luck you might get by with a finger instead of camera

Another alternative to thermal camera or “finger” is the “drench with isopropyl alcohol and watch which component evaporates the liquid fastest” method.

Either way, injecting voltage onto the suspected shorted rail is likely the simplest solution to finding the short without access to schematics and/or boardviews.

Karbist wrote on 2023-06-14, 15:32:

well check the other chips like the I/O chip on top of pci slots. you can also put your hand on the back of the board and feel what area is getting warm.

Finaly the southbridge is very hot 😒
I will try to replace the chipset...

Thanks

replacing this kind of chip is more expensive than sourcing another board

rasz_pl wrote on 2023-06-14, 16:15:

replacing this kind of chip is more expensive than sourcing another board

On ebay it's 250€ for a new motherboard VS 10€ for a new chipset.

If you have a BP6 in stock I’m interested 😉

oldgames79 wrote on 2023-06-14, 18:12:

rasz_pl wrote on 2023-06-14, 16:15:

replacing this kind of chip is more expensive than sourcing another board

On ebay it's 250€ for a new motherboard VS 10€ for a new chipset.

If you have a BP6 in stock I’m interested 😉

$80 2 months ago https://allegro.pl/oferta/plyta-abit-bp6-2x-p … tas-13598394244
its not the chip cost, but bga rework that might make it uneconomical

rasz_pl wrote on 2023-06-14, 18:17:

oldgames79 wrote on 2023-06-14, 18:12:

rasz_pl wrote on 2023-06-14, 16:15:

replacing this kind of chip is more expensive than sourcing another board

On ebay it's 250€ for a new motherboard VS 10€ for a new chipset.

If you have a BP6 in stock I’m interested 😉

$80 2 months ago https://allegro.pl/oferta/plyta-abit-bp6-2x-p … tas-13598394244
its not the chip cost, but bga rework that might make it uneconomical

Argh too late

Thanks for your help