Nm-a981

[Dinneke]

only red light brief flash (periodcally) without battery, with battery white light 4 sec

+5VALW and 3VALW turns off

no shorts found
any ideas?

[mon2]

Re: Nm-a981

Review the DCin mosfets.

Measure the voltages on each of the points in the attached.

ACDRV should be ~25 volts to enable the DCin mosfets.

[Dinneke]

Re: Nm-a981

20v
26v
20v

[Sephir0th]

Re: Nm-a981

"No shorts found" is a little less in my opinion. What's the resistance to GND of +5VALW, +3VALW, 1.8VALW and +1.0VALW to start with

[mcplslg123]

Re: Nm-a981

The light flash is the feature of many lenovo's-so dont indicate anything.

[Dinneke]

Re: Nm-a981

+5VALW >20k
+3VALW >10k
+1.8VALW > 40k
+1.0VALW 53ohm

notice that EC_ON goes on and off

[Sephir0th]

Re: Nm-a981

Does 1.8VALW and 1.0V ALW comes up too, or only 3VALW and 5VALW?

[Dinneke]

Re: Nm-a981

Does 1.8VALW and 1.0V ALW comes up too, or only 3VALW and 5VALW?

comes up just like 3VALW and 5VALW

[Sephir0th]

Re: Nm-a981

Well, then go ahead, and check the coils/power rails which were not mentioned before, the same way. so we maybe get a idea where it is Stuck.

[Dinneke]

Re: Nm-a981

found nothing of interest

[rediii]

Re: Nm-a981

check bios/ec firmware