820-00164 green light yes fan no

[Rford]

hey everyone,
have an 820-00164 that gave a brief display, and fan, then no fan and a sim green/orange light. Isl6259 was messed up, so I changed it out, seems to have fixed the dim mag safe light. Also changed burned components around lcdbklt_en. Have pp5v_s5 but no pp5v_ s4rs3 or S0. Any ideas?

 

[dukefawks]

PP3V3_S5 at L7560? Resistors around SPI ROM? Pulsing 5V_S5, check with scope.

 

[Rford]

3v3_s5 is present. At L7560. Resistors around SPI are Ok. Only thing that was visibly corroded after replacing the lcdbklt area, was one probe point opposite the lcdbklt_en area. It's completely burnt and gone. Could this be the cause? Also, scope is effed up.

 

[dukefawks]

Anything going on at L7520? Could be short pulsing...
U1950 pin 8 is of course also a prime suspect and crap around U1900.

 

[Rford]

Dead at L7520, u1950 has voltage at pin 8, looks like u7501 enable pin is not being "enabled". U1900 has voltage and looks fine around it. The burnt probe point is 1123 on the lcdbklt_en_div_l net. Think that would have a weird tie to it some how?

 

[dukefawks]

What is PPBUS voltage? Voltages on R1300/01/02/03?

 

[Rford]

At f7700- 8.6v
r1300-3- 3.42

so weird and feel like it's just at the tip of my fingers.

 

[Rford]

Also 17.01 all along the dcin circuit. Is this low? Should it be around 18?

 

[dukefawks]

Is SMC_LID high?

 

[Rford]

Smc_lid is reading 3.42v I can't remember if this is what it should read with the board out.

 

[dukefawks]

3v at pin 8 of U6100? J6100 checked and/or removed? SUS_EN present?

 

[Rford]

3.42 at pin 8 of u6100, j6100 I removed before posting original question. Just to be safe. PP3v3_sus is reading 3.34. Could it be the bios? If so, would one from a 3437 work on this board?

 

[dukefawks]

BIOS will be fine...
Check if PP5V_S4 is not pulsing, can be very hard to catch on a multimeter, scope is best.

 

[Rford]

No Title

Having some issues dialing in the scope. It doesn't appear to to register but my scales could be out of whack and they're not adjusting right.

 

[dukefawks]

1v/div vertical and 10ms/div horizontal should show something.

 

[Rford]

That's what I was afraid of. Nothing, no reading. I will say though, as an anomoly, the fan just started spinning for the first time for about 10 seconds... does that mean anything?

 

[dukefawks]

Corrosion under SMC maybe? U1950? Could be so many things....