820-3476-A

[iFix]

Hi guys.

I have this A1502 with no power. I have all power lines present, U1900 I replaced them just in case, PM_SLP_S4_L is present, no short anywhere. I had the camera chip U3900 heating up near contacts 14 and 29 and I removed it not heating up anymore. Now when I plug it in, as before green light comes on with no power and only U2800 warms up to nearly 30 degrees and nothing else. What I noticed is that when I have the SSD plugged in(tried 2, and one is known good) warms up the main controller on it up to 45-50 degrees and continues slowly up. Do any ideas come up, cause going in circles here

 

[2informaticos]

Do you have correct CPU core voltage?
PLT_RESET_L comes high?

 

[iFix]

PLT_RESET_L it's 0v. on the power trigger, it's 3v and reacts when pressed...
U1950 voltages:
pin1: 0v
pin2 : 3.3v
pin3 : 0v of course
pin4: GND
pin5/7: 0v
pin6: 0v
pin8: 3.3v

L7310/20 voltage not present

 

[2informaticos]

Pin 7 & 3 MUST reacts at same time with PLT_RESET_L.

If SSD gets hot, 3V3_S0 must be there.
That implies PM_SLP_S4/3_L presence.
Check voltage on SSD connector.

 

[iFix]

Yes PP3V3_S0 it's 3.3v.
Voltages on SSD connector:
Pin1/5 PP3V3_S0SW_SSD_FLT 3.3v
Pin 7 - 3.3v
pin 47 - 3.3v

 

[iFix]

btw i just noticed L7130 pin 1 it's 55.8v and pin2 normal at 12.6v. Not sure if Pin 1 should be like that

 

[2informaticos]

I told millon of times to people to check ALWAYS voltage on DC side (output) of a coil from buck converters!

"That implies PM_SLP_S4/3_L presence."
Did you check that?

 

[iFix]

Yes all are checked and i receive 3 and 5v for power , no shorts. PM_SLP_S4/3_L are pesent. Anything else?

 

[2informaticos]

Then you should have voltage on all coils, including CPU.

"PLT_RESET_L it's 0v. on the power trigger, it's 3v and reacts when pressed"
I'm not sure what this means.

 

[iFix]

"PLT_RESET_L it's 0v. on the power trigger, it's 3v and reacts when pressed"
PLT_RESET_L it's 0v.
on the power trigger button, it's 3v and reacts when pressed to power on.

I have PP1V05_S0_PCH_VCCAPLL_OPI, but no PPVCC_S0_CPU

 

[2informaticos]

Trigger and press power button is not the same for you?
Try to be clear.
You have all voltages before pressing power button, but PLT_RESET_L is 0V?
PLT_RESET_L (only) pulse to 3V pressing power button and drops when release the button?
Or it stays at 3V until press again power button?

 

[iFix]

ok to avoid confusion. When i press the power button PLT_RESET_L stays 0v no change

 

[iFix]

Also, when plugged in the power supply shows 0.084a on 16.5v and stays like that no change even i power button is pressed

 

[2informaticos]

Looks like missing ALL_SYS_PWRGD.
Which voltages are present and stable, when you connect charger?

Remove Q8150 and test the board again.

 

[iFix]

Without Q8150 i get on Bios, 3 and 5v, previously mentioned CPU voltage same, PPBUS_G3H is 12.6v, ALL_SYS_PWRGD 0v of course, but diode mode good ,Q7320/10 are 12.6v on PPBUS_S5_HS_COMPUTING. on Q7700 pin 3 and 4 i get 12.6v. There are all stable, anything else to measure?

 

[iFix]

Even with Q8150 all voltages are stable. I rechecked the board again for shorts and corrosion, but nothing found

 

[2informaticos]

Do you get L7430/630 and L7870 voltage?
If yes, start to remove the resistors from ALL_SYS_PWRGD (one by one).
Keep in place R8167.

 

[iFix]

The following are measurements without Q8150
L7430 - 0v
L7630 - pin1 5.4v and pin 2 1.05v
L7870 - 1.5v

This morning I just plugged in the adapter and I got a fan spin(no Q8150 on the board) and it goes high speed, of course, no picture or backlight.

 

[2informaticos]

Fix the RAM voltage now.
Check U7400 voltage, pins 12, 16, 17.
Be sure all resistors around are good.

"I have all power lines present"
Next time post them; avoid wasting time, because you forgot ONE!

 

[iFix]

U7400:
pin12 - 3.3v
pin16 - 3.3v
pin17- 3.2v
R7416 is 39k instead of 200k
R7415 is 17k but not a big difference it should be 19.6k
All other resistors around U7400 are fine, R8111 20k, R7418 51k, R7417 200k, R7401 is 10, R7425 is 0.

On C7401 PP1V35_S3 i have 0.080 diode mode and no voltage, and also on C7425 pin 2 diode mode 0.080 and no voltage