(347) 552-2258 [email protected]

820-3115B - Quarter Fan Spin

M

mushr00m

Member
Its in loop with quarter fan spin

IMPORTANT to mention.
I already reballed SMC, thinking that could be dust below it. So it would not be a problem anymore, the reballing was done perfectly


Some measurements below

  1. PPBUS_G3H = 12.52v stable
  2. PP3V42_G3H = 3.45v stable
  3. PP5V_S5 = 4.94v stable then tries to go to 5.07 when fan quarterly spin (ITS HAPPENING IN A LOOP)
  4. PP5V_S3 = 0V looks tries to go to around 0.250v and then backs to 0 same behavior as above in a loop
  5. PP5V_S0 = 0V looks tries to go to around 0.250v and then backs to 0 same behavior as above in a loop
  6. PP3V3_S5 = 3.3v stable
  7. PP3V3_S4 = Around 0.600v and then tries to go to 3.3v
  8. PP3V3_S3 = Around 0.300v and then tries to go to 3.0v
  9. PP3V3_S0 = Around 0.100v and then tries to go to 3.0v
 
M

mushr00m

Member
Also measure enable signals on U7200

U7200
ENTRIP1 = 0v then tries to go to 1.v in a loop
ENTRIP2 = 0.762v stable
 
2informaticos

2informaticos

Administrator
Staff member
Any fault history available?
Tried to start in SMC bypass mode?

Can you catch a pulse on all big coils?
Also check at ALL_SYS_PWRGD.
 
M

mushr00m

Member
Any fault history available?

It has dust below SMC and I reballed it, came back and customer work for a year. Then it stopped working and those are the measurements and behavior.

Once in a while it turn ON, but does not last long.

Tried to start in SMC bypass mode?
Did not try. Can I do it with the board unassembled on my desk mat as it is right now. Only board + dc-in jack

Can you catch a pulse on all big coils?
Not on all of them. CPU lines and PP5V_S3 do not show up


ALL_SYS_PWRGD = 0v then tries to go up to 3.2v
 
2informaticos

2informaticos

Administrator
Staff member
Possibly accumulated crap underneath PCH, or CPU.
Check R7402/03.

With board alone on the desk, you can use R5015/16 pads, instead of power button.
 
M

mushr00m

Member
R7402 = 149k ohms
R7403 = 181k ohms

R7402
PIN 1 = 12.52v stable
PIN 2 = 12.32v then looks like it drops to 3v and then back to 12.32V as the fan do the quarter fan spin

R7403
PIN 1 = 12.52v stable
PIN 2 = 12.32v then looks like it drops to 3v and then back to 12.32V as the fan do the quarter fan spin
 
2informaticos

2informaticos

Administrator
Staff member
Compare diode mode readings on the coils with good board.

Try heating PCH and CPU with quality flux.
May have luck to be accumulated crap underneath.
 
M

mushr00m

Member
did ultrasonic bath same beahvior
reflowed the CPU again still same behavior
reballed the SMC again still same behavior.

Now what?
 
2informaticos

2informaticos

Administrator
Staff member
Possibly bad CPU, or PCH.

But I still suspect some component damaged by corrosion.
Uñtrasonic bath can clean corrosion, but will not revive already damaged components.
 
2informaticos

2informaticos

Administrator
Staff member
Corroded component, or trace can be anywhere on PCH/CPU areas.
May have broken/corroded trace, or solder under them also.
 
You must log in or register to reply here.
Top