DA0P5HMB8F1 Turn on, no video, consumes only 22 mA

[ruletero]

Hi everyone

Model: DA0P5HMB8F1, Rev F

Please your help with this mobo, DA0P5HMB8F1, it turns on but no video appear and consumes only 22 mA, no suson signal, EC and PCH bios updated, no success.

It responds to power button and try to bring up without success and next it restart with the same cycle, it just restarts all the time, no schematic available, I'm using OP5D schematic, below my measurements on KBC



Any idea what I have to review?

thank you

[ruletero]

Sorry, I forgot to add I have +3VS5 and +5VS5 when it try to bring up.

[mcplslg123]

First check whether you have any short on switched rails like 3VS/5VS etc.

1.8V is present?

Measure resistance to GND on +3VS/+5VS/+1.8V.

Neither the boardview or schematic is accurate-so a little bit of struggle will be there to locate the exact rails.

[ruletero]

First check whether you have any short on switched rails like 3VS/5VS etc.

1.8V is present?

Measure resistance to GND on +3VS/+5VS/+1.8V.

Neither the boardview or schematic is accurate-so a little bit of struggle will be there to locate the exact rails.

Yes, 1.8v is present in coil, output of G2823D ic, but bios chip uses 3.3v.
.
No short in +3VPCU / +5VPCU / 1.8V, I am looking for these +3VS/+5VS

thanks!

[mcplslg123]

There is 14 leg dc-dc converter for switching rails from 3VPCU to 3VS. Same applies for 5V rail.

These dc-dc converter is located very close to 3V & 5V pwm controller.