820-3437B quarter fan in loop

Bouba148

New member
Hi team,

PPBUS_G3H: 8.59V
PP3V42: 3.401V
PPRTC_G3H: 3.310V
PP5V_S5: 4.994V
PP3V_S5: 3.310V
S4 State pulsing

SMC_ADAPTER_EN : 3.366V
PM_BATLOW_L : 3.305V
PM_DSW_PWRGD: 3.398V
SMC_PM_G2_EN: 3.396V

Checked all SPI Bus Series Termination traces and resistors
Put flux and heated SMC and SPI

Re programmed U6100 with medusa: NOK
Replaced U6100 and re programmed (Cleaned Pram, ME, SN Crc ): Not Ok
Still quarter Fan Spin
Sometimes When the medusa is connected fan starts running normally.
Re programmed with 00165 Dump bios just for try : Board Starts but no Chime, No backlight and No display.
Back to 3437B bios and pulsing state
Maybe not SPI finally
 

Bouba148

New member
@2Informaticos:

All big coils pulse too?
YES
Also check ALL_SYS_PWRGD and pins 3/7 of U1950.
Pulsing Too , everything pulses to Vcore

Did you try SMC bypass?
YES: Pusles too : forces the fan to enter in quarter Spin loop

@JohnB:

Yes checked and resoldered all pins : No sign of corrosion directely on the J6100 but Tests Points around have the gold color turned to brown

Board Starts only when the Medusa is writing which is very ennoying , I have to disconnect reconnect the charger many times during the process for the medusa to finish writing.
 
Last edited:

2informaticos

Administrator
Staff member
If coils pulse, means PM_SLP_S4_L pulses too.

"Board Starts only when the Medusa is writing"
Yesh, stays on, but doesn't work.
To avoid future problems with Medusa, dosn't use MacBook charger.
Inject external 3.3V on 3V3_SUS rail and never get problems again.

In this case, when the board stays on because of Medusa "help", check all voltages from pages 57/58.
 

Bouba148

New member
What's your idea reagrding: all voltages from pages 57/58?
do you think that one of those is shorted to gnd and drops down the PP3V3_S5?
 

Bouba148

New member
Page 57:

1.8V S3 REGULATOR:
1.8V Pulsing because P1V8S3_EN pulsing too.

1.5V S0 LDO:

PP1V5_S0 Pulsing as it's directely depending of 1.8V S3

1.05V SUS LDO:
PP1V05_SUS: 1.061V OK

Page 58:

PP1V5_S0SW_AUDIO_HDA Pulsing

3.3V SUS Switch OK

3.3V S4 Switch: Pulsing as depending S4_PWR_EN (Pulsing)

PP3V3_S3_FET_R Pulsing as P3V3S3_EN Pulsing too

3.3V S0 and PP3V3_S0SW_SSD pulsing as P3V3S0_EN pulsing

PP3V3_S4SW_SNS pulsing as SMC_SENSOR_PWR_EN pulsing

PP5V_S0 Pulsing as P5VS0_EN pulsing too

PP1V05_S0SW_PCH_HSIO pulsing as depending of PP5V_S0

PP1V05_S0 Pulsing
 

2informaticos

Administrator
Staff member
If power sequence is OK, then should be communication problem between some blocks, maybe bad CPU.
Check if PLT_RESET_L and BUF_PLT_RST_L pulse both high.
 
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