[SOLVED]820-3115 no green light ADAPTER_SENSE missing

[dukefawks]

If 3V3_S3 is present then 5V_S3 should be there too. The enable for both comes from SLP_S4, 5V_S3 enable is inverted by Q7911. Measure voltages on Q7911 and Q7221.

 

[ytesfay80]

I have 3.3v on SLP_S4_L and now I just get 0.18v on 5V_S3 while 3V3_S3 is 3.3v. U1800 is still getting slightly warm.

Q7911
Pin 1 - 3.325v
Pins 2 & 3 - 0v

Q7221
Pin 1 - 0v
Pin 2 - 0v
Pin 3 - 0.78v
Pin 4 - 0v
Pin 5 - 0v
Pin 6 - 0v

 

[dukefawks]

Isn't there just a short on 5V rail? Else it must be around U7200, resistance to GND on ENTRIP1?

 

[ytesfay80]

There is not a short on the 5v_s3 rail. In diode mode 5v_S3 is showing 0.153v.
In voltage mode I get 0.18v on 5v_S3 and 5.02v on PP5V_S5.

Resistance to GND on ENTRIP1 is 78.6 kohms

I have already replaced U7200 and that didn't fix the issue. Actually before replacing U7200 a couple of days ago I was getting 2.55v on 5V_S3 and 5V_S0.

 

[dukefawks]

Could be Q7221, but I still suspect something around U7200. Possibly the FETs or a trace, check all the stuff around it.

 

[ytesfay80]

I replaced Q7221 and that solved the issue and now this turns on and works fine.

Thanks a lot Duke for your time.