820-00165 no boot

wgaca

Member
Originally there was damage on Y1905, U3510 and C7540. Very isolated damage.
Nothing looked corroded, just cleaning the liquid stains (probably had sugar) was enough to see that the parts were not visibly damaged.

I will post the measurements, but keep in mind that I already tried replacing Y1905, U1900 and I checked with another bios to ensure that's not the issue.

PPBUS_G3H - 8.58V
PP3V3_S5 - 3.3V
PP5V_S5 - 5V
PPVRTC_G3H - 3.3V
PP3V3_TBT_LC - 0.5V

SYS_CLK_CLK25M_X1 - 0.6V-0.7V
SYS_CLK_CLK25M_X2 - 0V

RTC_RESET_L - 3.3V
PCH_INTVRMEN - 3.2V
PCH_INTRUDER_L - 3V
PCH_SRTCRST_L - 3.3V
PCH_DSWVRMEN - 3.2V

PP3V3_SUS - 3.3V
SPI_MLB_IO3_HOLD_L - 3.3V
SPI_MLB_CLK - 3.3V
SPI_MLB_IO0_MOSI - 3.3V
SPI_MLBROM_CS_L - 3.3V
SPI_MLB_IO_MISO - 3.3V
SPI_MLB_IO2_WP_l - 3.3V

PM_SLP_SUS_L - 3.3V
PM_SLP_S5_L - 0V (Pulsing on start)
PM_SLP_S4_L - 0V (Pulsing on start)
PM_SLP_S0_L - 0V (Pulsing on start)

PP3V3_S4 - 0.34V (Pulsing on start)
PP3V3_S0 - 0V (Pulsing on start)
PP5VS4_RS3 - 0V (Pulsing on start)
PPVCC_S0_CPU - 0V (Pulsing on start)

I figured many rails are present for a second on charger connect while writing this post.
Is there any way I can find what is causing it to pulse without measuring every capacitor on the board for short?

Resistance to ground:

PP3V3_S0 - 2.2k
PP5V_S0 - 3.6k
PPVCC_S0_CPU - 8.4 ohm

The board takes 0.02 Amps when connected to a power supply with a MagSafe cable.
 

2informaticos

Administrator
Staff member
Do you note a power cycle, or just 1, or 2 pulses when connect charger?
See what happens in SMC bypass mode.
 

wgaca

Member
In SMC bypass mode it will do 2 very short fan spins and nothing else.
In normal mode it will do 2 short pulses as well.
 

2informaticos

Administrator
Staff member
Be sure all SPI Bus Series Termination resistors are good, as their traces too.
Clean/remove J6100.

Do you get pulse at pins 7 & 3 of U1950?
 

wgaca

Member
All the resistors are good and the traces have no damage.
J6100 is flawless

both 7 and 3 have 2 pusles
 

wgaca

Member
Tried the CPU, didn't work. The only crap on the board was around the clock chip, u3510 only this chip and a bit went down to c7540 and C7582. It wasn't something corrosive so it didn't cause any corrosion anywhere.

I took out the SMC just to make sure that's not the issue, was clean.

Any other ideas?
 
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