820-3476-a A1502 Fixed blown cap and resistor and still has issues.

[Cire3]

820-3476-a

A1502 Fixed blown cap and resistor and still issues.

Came in no boot. Removed logic board and found C7536 blown, C7537 and R7536 looked like hell.

Replaced them both, and unit had fan spin. Reassembled unit and no boot ?

Ok, let's take it back apart. Power supply shows 0.09A draw. Light goes green, then orange. After a quick wander, again 0.09A

What I do find odd, SSD gets warm, however no chime, no fan and CPU is cold.

Thoughts from here?

 

[2informaticos]

What voltages do you get on the big coils?
Use original 60/85W Magsafe 2 charger.

 

[Cire3]

L7520 0V
L7130 12.6V
L7560 3.35V
L7310 0V
L732 0V
L7430 0V

 

[2informaticos]

So you have only 3V3_S5; what about 3V3_SUS?

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L (at same time).

 

[Cire3]

Checked 3v3_SUS @

U6100 pin 8 ,C6100, R6101, U8130 Pin 2, R8133, R1583, R1581, R1590, R1580, C1206, C1202, C1204, R1549, R152.

All pined @ 3.3V

I'm a bit green.. Would need help with " Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L "

Not sure how this is done?

 

[2informaticos]

I hope this thread helps you:

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

BTW, no need to measure the voltage of a power rail in more than one point.

In case you detect drop pulse on PM_PWRBTN_L, check for pulse at PM_SLP_S4_L too (at same time).

 

[Cire3]

That document most definitely helped me, big thanks ! Do we have an area for docs like this ?

PM_PWRBTN_L, check for pulse at PM_SLP_S4_L : Both pulse when I ground SMC_ONOFF.

It drawn a little more power briefly, then goes back to drawing 0.09A

 

[2informaticos]

Check for pulse at all big coils; at same time when trigger SMC_ONOFF_L.
Also check ALL_SYS_PWRGD for pulse.
Inspect U1950 for corrosion.

Test strating in SMC bypass mode, just in case.