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820-00165

I

iMuhtaseb

Member
This board came in for no power; PPBUS was shorted, inject 1V and took off the bad cap, which was C7324.. now PPBUS is clear of short.
But the board is still not powering on; after visual inspection I found out that had corrosion on pin #2 and #3.. I replaced the chip and the board is still refusing to power on..
Although the symptoms are different where I get a fan spin.. then stop.. then a continuous fan spin.. if I unplug and replug.. I get no fan whatsoever..

When then fan spins I get PP1V05_S0.. Any clue on where to look?
 
I

iMuhtaseb

Member
I’ll do that tomorrow. Its weird that its either as simple as just replacing a fuse or an internal failure.

question: can i use just a wire instead of F7140 just for testing purposes?
 
I

iMuhtaseb

Member
Fuse replaced; still behaving the same..
I really cannot rely on voltage readings because when I start probing around.. PPBUS or 3v3_S4 or anything the fan spins..
So I took the diode mode readings of all power rails and it all seems to fit with 1. FlexBV (although my readings were higher in all readings I guess that's for the multimeter differences) and 2. another board that I have.

What was a bit suspicious to PP1V05_S0 so I replaced U8005; same issue
also PP1V05S0_DRVH_R was kinda weird going up then down.. I replaced both U7600 and Q7630; same issue

Dunno what's wrong with this board.. it was supposed to be a clean easy job of PPBUS_G3H; take it off and boom happy A1466...
 
2informaticos

2informaticos

Administrator
Staff member
When the fan starts to spin, do you get CPU core voltage?
Are you using original Magsafe 2 charger?
 
2informaticos

2informaticos

Administrator
Staff member
You should use better way to confirm USB activity.

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 boards.rossmanngroup.com

If board really boots always out of case, then put it back and start connecting devices one by one.
See when the problem appears.
 
I

iMuhtaseb

Member
No USB Activity, sadly.

The computer is behaving weirdly I'm going to describe it as much as I can:
A normal bare board power on behavior for 820-00165 when you plug in the MagSafe charger should be a take a few seconds to turn on the fan then a continuous fan spin remains.

This board is different; I don't get the fan spin as soon as I plug in the charger.. I might get it 30 seconds after or "randomly" when I probe around areas.. and now (I say now because it's different than it used to) when the fan spins it does for 5 seconds then it shuts off..
 
2informaticos

2informaticos

Administrator
Staff member
Check if fan spins when start with LIO flex disconnected; keep connected only power cable between LIO and MLB.

When fan stops, which voltages remain on the MLB?
 
I

iMuhtaseb

Member
Without the LIO flex cable connected the fan is not spinning at all.. I gave it its time; nothing.. I probed around; nothing.

I started measuring for voltages;
PPBUS = 8.6v
RTC = 3.3v
PP5V_S5 = 5V
PP5v_S4 = not there. diode mode 0.440
PM_SLP_S4_L not there. diode more 0.500
 
2informaticos

2informaticos

Administrator
Staff member
May have accumulated crap underneath CPU.
You can try heating it with quality flux.

I also recommend to reball SMC.
 
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