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820-3476 missing PM_SLP_S4_L

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Fizzl92

Member
That was at 50 mV/div and 5 us/div. All_SYS_PWR_GD shows a different behaviour. If i connect the adapter it just has a single pulse to ~3 V but it is so fast that i cant capture it. After that its back to 0 V.
 
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dukefawks

Administrator
The 3V spike on ALL_SYS would suggest the board tries to power on once. I still suspect a short on a rail or possible corrupt BIOS.
 
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Fizzl92

Member
I measured the resistance of all rails and added the values to the table. The new values are blue. I added a picture. I will try a new Bios chip today too and let you know if that changes something...
 

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dukefawks

Administrator
You read it with programmer. The chips on some of the China boards are erased. If it was a donor that was not from China then it is probably fine.
 
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Fizzl92

Member
I put the original Bios IC back on and read the china Bios with my progeammr and a new small PCB where i can solder these Bios ICs on. It is not empty and can be read without any errors.
 
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Fizzl92

Member
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No problem. Thank you for the outstanding help. Even if it it may be dead i could learn the troubleshooting process.
In the mean time i got another 820-3476 in (i could fix this one and it still works fine). So i took all resistance measurements again from this working board, added the values to my sheet and uploaded it here. Only PP5V_S4 and PP5V_S0 are noticable lower than the values from the working board. So maybe this could be the last chance for this board...
 

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Fizzl92

Member
I have no explanation for this! No idea why PM_SLP_S4_L was missing. (this signal is really confusing to me) But i followed the lower resistance values (even if the diode mode readings were the same - i also dont really understand how that could be) and there are only three places where PP5V_S4 and PP5V_S0 meet. And only U8080 makes sense here. So i replaced U8080. The diode mode readings did not change but the resistance readings came back up and - i could not belive it- the board turns on. So i dont know what to say at this ponit except thank you very much for your great help and patience.
You and this whole forum are amazing!!!
 
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Titotinton

Member
SMC_ADAPTER_EN is ok, ppbus is ok,PM_SLP_S4_L is pulsing ! PPVRTC is ok!

Sorry and let me know if i have to open new topic, and i will!! Sorry but this case is very very near to mine!!

Thanks
 
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