820-2523 right fan high (0 RPM)

[BCN_Techs]

Got this board. No water damage.

Right fan is always high. When start it has some delay and after 2-3 seconds start run very high.


Already changed U5570 and Q5501. Same result.

Run AHT and it it gives me 3 errors:

Fan-Right side (test1) Qiuck motor test-> Error - MOtor is spinning slower than should

Same with test 2 fo right side fan


And

CPU Front Side Bus (1,05V) current (test) -> Sensor is reading above the high limit. +

 

[2informaticos]

Check traces and components around U5440.
Also check continuity to R7660.
Post SMC_CPU_FSB_ISENSE level.

 

[BCN_Techs]

Near u5440 all is ok.


R7660 you mean continuity on same resistor? If so there is continuity there is 1.05V on both sides.

SMC_CPU_FSB_ISENSE 3.3V

 

[2informaticos]

R5495 is good for sure?

Post U5440 voltages.

 

[BCN_Techs]

R5495 4.5 Kohms


U5440:

1 - 0,8V
2 - 1.5V
3 - 1.5V
5 6 - 1.05
7 - 0.6V
8 - 3.3V



Must change U5440 ? I see that entering voltage is ok but outgoing is low, right? Must be about 1.05 on Pin 1 and 7

 

[2informaticos]

"SMC_CPU_FSB_ISENSE 3.3V
------------------
7 - 0.6V "
Cannot be true, if R5495 is good...
Do you have continuity between U5440 and R5495???

BTW, U5440 output voltage is correct.

 

[BCN_Techs]

ALl measerment were done when board was on.

If board is off:


1- 6 are 0V
7 - 1..05V
8- 0.5V


There is continuity from U5440 Pin 7 to R5495 and R5495 is 4.5 Kohms

 

[2informaticos]

Who cares about off state, if is an S0 voltage?

R5495 MUST have the same voltage on both pins.
You may need to change SMC...

 

[BCN_Techs]

Just reflow SMC and now it is working. but anyway R5495 has 0.5V on pin 1 and 3V on pin 2 but fan not running high speed like before.