Again, A Retina MBP 820-3476 Green/Orange light, missing S4 Rails.

[punkieftw]

Ok, here we go again, i have a 820-3476 (Again) missing all s4 and obviously S3,S0 Rails.
The last time i post one here and we could not solve. so, again.. thats my measures.


PPBUS_G3H is present. i little bit fluctuant like 12.48.. 12,49.. 12,55.. 12,56.. (i think this is trying to get power on)
PP3V42_G3H Is present
PPVRTC_G3H present
PP5V_S5 present
PP5V_S4 missing
PP3V3_S5 present
PP3V3_S4 missing.

missing PM_SPL_S5_L, S4_PWR_EN, PCH_PWROK, PM_PCH_SYS_PWROK too

this board is pretty clean, no corrosion, no liquid damage.

SPI Bios area looks good, and i measure this signals too
PCH_SUSACK_L Present
PM_SYSRST_L = 0.20v (wierd)
PM_PCH_SYS_PWROK = Missing
PM_PCH_PWROK missing
PLT_RESET_L missing
PM_RSMRST_L Present
SMC_ADAPTER_EN Present
PM_BATLOW_L Present.

i want to know what could i do..

 

[dukefawks]

DSW_PWRGD present? Checked the usual corrosion points, U1900/50 U6100 and termination resistors and traces? Check for power cycling on 5V_S4

 

[punkieftw]

DSW_PWRGD present? Checked the usual corrosion points, U1900/50 U6100 and termination resistors and traces? Check for power cycling on 5V_S4

DSW_PWRGD Is present, No corrosion on U1900/U1950 and u6100 neither. what do u mean with "power cycling" ? i checked 5V_S4 for a long time to see if this for a second gets high but never appears.

 

[dukefawks]

If it power cycles it will not be a second. If you have a slow multimeter it will never pick it up. Use a scope or connect a LED+resistor to see the pulses.
What is the history of this machine? Checked rails for shorts?

 

[punkieftw]

If it power cycles it will not be a second. If you have a slow multimeter it will never pick it up. Use a scope or connect a LED+resistor to see the pulses.
What is the history of this machine? Checked rails for shorts?

Hello, thanks for the answers. i soldered a led attached to 5V_S4 and never get any pulse at this line. no shorted to ground on 5V_S4 and 3V_S4 Neither.

what do you think?

 

[dukefawks]

3V3_SUS present? Did you solder a resistor is serie with the LED, else the LED got 5V and is dead now of course, polarity of LED correct?

 

[punkieftw]

Yeah, 3V3_SUS is present. The led is fine, i solder 1 pin of resistor to ground, another pin of resistor to cathode of the led diode, and the anode attached to 5V_S4. i know the diode is fine cause i try again with a power supply with 5v. and it's fine. the resistor is a 100 Ohms resistor.

 

[dukefawks]

OK, assuming you are using a good 60W or 80W charger the most likely thing would be SMC/crap under SMC. Check 32KHz from U1900 also.

 

[punkieftw]

Ok, to check this i need an oscilloscope right? another question is, i have a same board but, with some differences. the board to repair have 16GB Ram, and that donor board have 8 or 4Gb ram. i can replace the smc from the donor?

 

[dukefawks]

3536 and 3476 are the same.

 

[punkieftw]

3536 and 3476 are the same.

Ok, and about the oscilloscope, i need one to get mensures like 32Khz right?

 

[dukefawks]

Some multimeters have a frequency counter up to 40kHz. If not then either get a scope or multimeter with counter.