820-2850 green light. No fan spin.

[protocold]

Board looks very clean.

PPVCORE_S0_CPU = 0v and diode mode = 057.

PP5V_S0 = cycling. PPBUS_G3H cycling.

If removed F7040, pin 1 cycling

U7000
pin 3 = 4v
pin 14 = 3.3v
pin 27-28 = 20.8ohm
pin 17-18 = 3.3ohm

 

[2informaticos]

Post basic voltages for U7000; pins 1, 2, 3. 9, 12, 13, 14, 15, 17, 19, 20, 27.

 

[protocold]

1 = 15v cycling (measured at R7086 pin 2)
2 = 16.5v
3 = 4v
9 = 0.03v
12 = 3.4v
13 = 3.4v
14 = 3.3v
15 = 0.05v
17 = 12.5v cycling
19 = 5v
20 = 5v
27 = 16.3v cycling

 

[2informaticos]

How is cycling C7040 voltage?
Can you post some values?

Just in case, change Q7080/85.

 

[protocold]

removed 7040 pin 1 = 12.5v cycling = C7040 voltage.

Q7080 pin 1 is 16-16.3v which goes into R7085 pin 1 but pin 2 is cycling... bad Q7085?

 

[2informaticos]

Cycling...
Can you post the values???
0-12.6V is not the same as 12.3-12.6V, for example.

Did you try fake charger, or lab PSU.
Also, this board requires 85W charger, if battery is not connected.

 

[protocold]

85w genuine used. Did not try fake charger

it is 0-12.6v cycling.

 

[2informaticos]

Put back F7040 and test again.

 

[protocold]

ok i dont know why.. but i put back F7040, on real 85W, now fan spin and stop, DELAY, spin and stop....sometimes the delay seems longer and sometime shorter..

With a fake charger, voltage at F7040 is 12.5v, no fan spin.

 

[2informaticos]

Steady 12.5V at F7040 with fake charger?
But fluctuates with original charger?
If yes, then change Q7080/85.

Just in case, try to start in SMC bypass mode.

 

[protocold]

Changed both Q7080/85 and now 12.5v at F7040 seems to be more stable but i still find occasionally my multimeter will see it drop below 2v and bounced back (maybe it goes to zero but i think my multimeter is too slow), but voltage not as cycling as before. Fan still spin up and down.

Fake charger still stable at 12.5v at F7040, no fan spin on fake charger. (Just compared to another working 820-2850 it seems this fake charger doesnt work on these 2850 boards. Just no fan spin!)

But in SMC bypass mode: both real and fake charger it is on with high spin fan on and off....

 

[2informaticos]

Fake charger has 85W cable?
If not, connect charged battery (plus charger) and press power button.

 

[protocold]

you mean i should not use real charger to troubleshoot this bad board now?

I should use battery + fake charger to connect to this bad board now?

 

[2informaticos]

Yes, for test.
Original charger detects some leakage and that should be the cycling reason.

 

[protocold]

oh my fake charger is only 60W...

can i just connect battery + fake charger + short SMC_ONOFF_L to ground instead of a power switch? I dont have it mounted inside the case right now...

 

[2informaticos]

Of course, read this...

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

 

[protocold]

ok, i didnt have to short SMC_ONOFF_L to ground..

when i plug the battery, plug the fake 60w charger.. I see orange led and the fan still spin on and off...

i might have a psu somewhere but i havent really used one..should I try?
(16.5v 4A will it work? i have a magsafe cable that i can hook it up to...)

 

[2informaticos]

You need 85W cable, if you want to test without battery.

 

[protocold]

ok i have hooked up that magsafe cable to the psu.. fan spin but with the same on and off pattern....

SMC bypass mode also the same, high speed fan on and off pattern...

I did compare diode mode values on big coil with a good board, all values seems value EXCEPT:
L7530 on bad board is 140 and good board is 60

Is this a problem?

 

[2informaticos]

Board power cycles every 5s?
Which coils get voltage?
What about ALL_SYS_PWRGD?