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820-2530 No Power No S3

Bouba148

Bouba148

New member
No History
Doesn't Power ON No Green Light ( Very dim)

PPBUS_G3H: 12.58V
PP3V42_G3H: 3.418V
ADAPTER_SENSE_R: 16.44V

Replaced the magsafe connector board:
Green Light OK
ADAPTER_SENSE_R: 3.398V

Then no S5 State

PP3V3_S5: 0482V if L7220 removed then 0V on Pin 1
3V3S5_ENTRIP: 0V
SMC_PM_G2_EN: 3.396V

Replaced U7200:
PP3V3_S5: 3.317V
PP1V1R1V05_S5: 1.059V

Then No S3 State
When shorting the power pads PM_SLP_S4_L is pulsing

At MCP79 (U1400):

SMC_ADAPTER_EN: 3.401V
PM_BATLOW_L: 3.313V pulsing to 0V when shorting the power pads
PM_PWRBTN_L: 3.417V pulsing to 0V when shorting the power pads
RTC_RST_L : 3.403V solid even if shorting the power pads
MCP_PS_PWRGD : 0V and slightly pulsing when shorting the power pads
32kHz is OK

Mesured the resistance to gnd of PP5V_S3, and I have around 20 Ohms and in diode mode it's 0.021V which is too low and means that I have a "short" to gnd on that rail.
Removed L7620 and the short is on the pin 1 side the same for R7267 not on the U7200 that I've already replaced before....
Lifted C7290, C7291,C7293 and C4801 still have the short.....
After a deep inspection of the board I've noticed that C6603 was fried and removed it: still the same.
So I also removed all the audio amps and their capacitors: U6610,U6620,U6630, C6601 and C6605 and the short is still present......it could be anywhere on the PP5V_S3 rail.......but now the resitance to Gnd is 26 Ohms....
 
Last edited:
Bouba148

Bouba148

New member
I will check all the associate rails to PP5V_S3_REG:
=PP5V_S3_P5VS0FET
=PP5V_S3_ODD
=PP5V_S3_AUDIO_AMP
=PP5V_S3_AUDIO
=PP5V_S3_1V5S30V75S0
=PP5V_S3_TPAD
=PP5V_S3_WLAN
=PP5V_S3_VTTCLAMP
=PP5V_S3_MCPDDRFET
=PP5V_S3_SYSLED
=PP5V_S3_IR
=PP5V_S3_BTCAMERA
=PP5V_S3_EXTUSB

As it's a long job and this board is not urgent I'll do few of them time to time
 
2informaticos

2informaticos

Administrator
Staff member
Check first resistance to ground on 3V42 power rail in ohm scale; you should get more than 30K.
Lower value points to bad MCP...
 
Bouba148

Bouba148

New member
Resistance to GND for PP3V42 is 2.5KOhms

And here my mesurement regarding "short" on PP5V_S3.......but if the MCP is bad It doesn't worth to continu removing the ones I haven't done so far.....

Removed components:

For PP5V_S3_P5VS0FET: Q7940
For PP5V_S3_ODD: Q4590
For PP5V_S3_AUDIO_AMP: U6610, U6620, U6630, C6601, C6603, C6605
For PP5V_S3_AUDIO: U 6200, U6500, C6213
For PP5V_S3_1V5S30V75S0 : R7307 and C7302
For PP5V_S3_WLAN: Q3450
For PP5V_S3_TPAD: R5873 ( short stay on pin 1) , C5800, R5805 ( short stay on pin 2)
For PP5V_S3_SYSLED: R5030 short stay on pin 1
For PP5V_S3_MCPDDRFET only checked Pin 2 of R7901 and R7903 for short: None
For PP5V_S3_VTTCLAMP only checked fort short on Pin 2 of R7976: None
For PP5V_S3_BTCAMERA: Removed L3405 looking for short on the Camera connector: None
For PP5V_S3_IR: R4532 short stays on Pin 2
For PP5V_S3_EXTUSB: U4690 and C4691

Next Time I Will still have to remove U6201, U6700 for PP5V_S3_AUDIO
and U4800 C4801 for PP5V_S3_IR

Please confirm regarding bad MCP......
 
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