Hello. Needs some help with this one. I have a PS5 EDM-044 that does not turn on. It does not beep or show any signs of life. I checked the power supply and it is putting out 12v. I removed the board and checked the amp draw using my bench power supply and it draws about 85 ma during the initial startup and then drops to 8 ma. Tried to pull UART codes but it fails to connect, even with it connected correctly. I could not find any shorts on the board so I thought it could be a BIOS issue so I flashed the Bios chip with a working version from the same model board, but no change.
During testing I did manage to get it to randomly give me 230ma during initial startup, so I put it back in the case and it beeps when you press the power button now and then the blue light stays solid. It does not flash or pulse and never goes to white. Fan is spinning and the power button becomes unresponsive. I can only shut it down by pulling the power cable and then it will go back to the 85 ma power draw and show no signs of life again. I found that I can get it to start up to the solid blue light by removing the CMOS battery from the board and the reinserting it. After doing that it boots to a solid blue light again and then back to the same issue with no signs of life. I did connect UART again with the board giving me 230 ma on startup and this time it does connect but shows the log is completely empty with no errors. I compared this board to a working board under thermal imaging and the working board shows significant heat on the SB while its running. This one shows either no heat or very little heat coming from the SB when the board is stuck in solid blue light, so I think the SB is turning off or not responding properly. I replaced the southbridge with one from Aliexpress but still have the same symptoms. I would like to compare diode reading of the pads for the SB on the board. Do you happen to have a pad map with the diode values for the SB?