Latitude E5250 dead. La 89 motherboard

[Herbssat]

Hello guys. This motherboard has no signs of life after turning off one day. Disassembled the machine and took the bios battery out then pressed the power button for 30 seconds. Board turned on again momentarily but was short lived and didnt turn on again. Flashed bios with a 341a programmer and no change. Board has no shorted power rails and is outputting 3.3v and 5v alw. No other rails are present when pressing the power button and the voltage is there. Also no voltage drop at the power switch when pressed like its not even there. Running out of ideas on this one. Any help is appreciated.

[Herbssat]

Re: Latitude E5250 dead. LA -A89 motherboard

Hello guys. Looks like the problem may be at UZ8 that supplies +3.3V_M and +3.3V_ALW_PCH. The LDO regulator has no output but has input voltage. I have a donor board or two but those chips are a pain to take off. Still looking for suggestions. Thanks.

[mcplslg123]

Re: Latitude E5250 dead. La 89 motherboard

No voltage drop at power switch-means mb is not switching at all.So your comments on post#2 is simply invalid as enable for UZ8 will come only after triggering.

since its totally dead,i'll suggest to check the following:
01.Flash known good bios
02.Check RTCRST#/SRTCRST# prsent or not
03.Check basic requirements of SIO and see if RSMRST# is present or not.

[Herbssat]

Re: Latitude E5250 dead. La 89 motherboard

Thanks for the reply and suggestions friend. I will certainly check what has been suggested but need some clarity on what has been referred to as invalid. I have another identical motherboard here that i am taking readings from and looking at the diagram. On UZ8 at vout 2 shows the alw voltage as 3.3v and that voltage is measured at PJP 20 with no motherboard triggered. Once the power button is pressed the 3.3 M voltage is shown on pin 13 and 14(Vout 1) and goes away when power goes off. From what i can see the chip must be bad. PJP 20 resistance to ground= 23.94K. Please correct me if i'm wrong as we are all here to learn more and thanks for all you do on this forum.

[mcplslg123]

Re: Latitude E5250 dead. La 89 motherboard

This is exactly what i've suggested. UZ8 will output voltage only after trigerring.It needs enable to convert 3.3ALW to 3.3M .So UZ8 is very likely not the culprit here and that's why i said your assumption seems wrong to me.