I brought this board because i have another one the same (which i still haven't fixed, due to parts not arriving) and it can be good to have two for the sake of comparison
It was a non-working board, with no shorted power rails
I connected it to a PSU, and the CPU fan briefly spun (can't recall if it was before, or after, pushing the power button)
As i was probing the thermal protection chip ATTP1 voltages, the PSU flashed and made a bang sound, and blew the top off of a TNY276PN chip that's inside the PSU.
May have just being coincidence
So i got another PSU, (this time, connected to a dim bulb tester), but no rail voltages attempt to come up (even after connecting the PSU directly to the wall socket)
------
PSON (green wire) is not being pulled low when pushing PWRBTN,
so the PSU wont start
RSMRST# comes up as 3.2V when the PSU is plugged in
This board is starting powered on, so to speak - because voltages of around 3.1V are already present on SLP_S3# and SLP_S5# without pushing the power button
So, i hold the power button in for a few seconds, to make the voltages drop off
Briefly pushing then power button brings them back up again
Looking at the attached schematic (thumbnail):
PSON (-PSON) goes to pin 6, PSON_OUT#, of U1 (ATTP1, Thermal protection chip)
When power button is pushed, pin 3 (3.5V) drops to 76mV and pin 6 (5V) stays high
Holding the power button in brings the voltage back up on pin 3
If i remove the CPU, the same happens (except pin 3 goes from 4.63V to 76mV when button is pressed)
So i guess that that means that power is getting to the base of the transistor Q4 in on order to pull pin 3 low.
From my understanding of the description of ATTP1, it seems that if pin 3 (PSON_IN#) is pulled low (as a result of the attached transistor being turned on) then pin 6 (PSON_OUT#) should also be pulled low (except in the event of a thermal event, where pin 6 is pulled high), and then the PSU should start up.
I checked the resistors and capacitors that are attached to pins 4 and 5, and they are good
Using another CPU (with lower frequency) increases the pin 3 voltage to 4.64V, but still same story as above.
The base of the transistor Q4, SLP 3# looks like comes from the southbridge, and it's also on the ACPI chip.
I checked the southbridge chip for visible damage, but it looks OK.
Any tips/suggestions would be appreciated
It was a non-working board, with no shorted power rails
I connected it to a PSU, and the CPU fan briefly spun (can't recall if it was before, or after, pushing the power button)
As i was probing the thermal protection chip ATTP1 voltages, the PSU flashed and made a bang sound, and blew the top off of a TNY276PN chip that's inside the PSU.
May have just being coincidence
So i got another PSU, (this time, connected to a dim bulb tester), but no rail voltages attempt to come up (even after connecting the PSU directly to the wall socket)
------
PSON (green wire) is not being pulled low when pushing PWRBTN,
so the PSU wont start
RSMRST# comes up as 3.2V when the PSU is plugged in
This board is starting powered on, so to speak - because voltages of around 3.1V are already present on SLP_S3# and SLP_S5# without pushing the power button
So, i hold the power button in for a few seconds, to make the voltages drop off
Briefly pushing then power button brings them back up again
Looking at the attached schematic (thumbnail):
PSON (-PSON) goes to pin 6, PSON_OUT#, of U1 (ATTP1, Thermal protection chip)
When power button is pushed, pin 3 (3.5V) drops to 76mV and pin 6 (5V) stays high
Holding the power button in brings the voltage back up on pin 3
If i remove the CPU, the same happens (except pin 3 goes from 4.63V to 76mV when button is pressed)
So i guess that that means that power is getting to the base of the transistor Q4 in on order to pull pin 3 low.
From my understanding of the description of ATTP1, it seems that if pin 3 (PSON_IN#) is pulled low (as a result of the attached transistor being turned on) then pin 6 (PSON_OUT#) should also be pulled low (except in the event of a thermal event, where pin 6 is pulled high), and then the PSU should start up.
I checked the resistors and capacitors that are attached to pins 4 and 5, and they are good
Using another CPU (with lower frequency) increases the pin 3 voltage to 4.64V, but still same story as above.
The base of the transistor Q4, SLP 3# looks like comes from the southbridge, and it's also on the ACPI chip.
I checked the southbridge chip for visible damage, but it looks OK.
Any tips/suggestions would be appreciated
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