820-00165-A Quarter Fan Spin

LCDR2

Member
Hi

Quarter fan spin when battery connected.
With no battery connected no boot / fan spin.

PPBUS G3H 8.2v
PP3V42 G3H 3.4
PP5V S5 5v
PP3V3 3.3v

I replaced capacitors C1992 and C1902 as they looked damanged

Thanks in advance.

James
 

2informaticos

Administrator
Staff member
"PPBUS G3H 8.2v"
Is this without battery connected?
Post voltage and diode mode to ground at SCL/SDA lines of battery bus.

Do you get 3V3_SUS?
 

LCDR2

Member
"PPBUS G3H 8.57 with no battery, 8.38 with battery
3 V3_SUS 3.29v with and without battery

is battery bus U7100 ?
 

LCDR2

Member
Voltages

SCL - 2.9 - 3.4 (fluctuates)
SDA - ditto

with battery and PSU connected.

SCL 0.477
SDA - 0.457
 

2informaticos

Administrator
Staff member
I'm not sure if you checked diode mode with power applied on the board.
If yes, do NOT do it again ever!

However, 8.57V is good voltage for PPBUS_G3H, so no reason to check there anymore.
Keep battery out, until get the board starting with charger alone.

"With no battery connected no boot / fan spin."
Do you mean the board stays on, fan spins continously, but doesn't boot?
If yes, check PLT_RESET_L.

Any history fault available?
 

LCDR2

Member
Hello

No power supply connected with Diode Mode.

"With no battery connected no boot / fan spin."
- With no battery connected, the laptop does not do quarter fan spin, or boot in any way.

Computer was "fine" before customer brought it in.
 

LCDR2

Member
So to clarify
With no battery connected, computer will try to boot, drawing about .185a then restart approx every 3 seconds.
the fan does not move.
 

2informaticos

Administrator
Staff member
Use original 45/60W Magsafe 2 charger for tests.
See if board stays on in SMC bypass mode.

If board restarts every 3s, is power cycling.
Check if appears voltage pulse on all big coils; especially PCH/CPU.
Also check for pulse at ALL_SYS_PWRGD and PLT_RESET_L.
 
Last edited:

LCDR2

Member
Hello
In SMC bypass mode the board does the 3 second thing.

(Just checking, hold down power, plug in magsafe, hold power button for 10 seconds, release) Fan immediately spins but ony for a second.

I'm not 100% sure what you mena by " all big coils; especially PCH/CPU. " but this is what I've checked

L7310 - 3.2v
L7320 -3.9v
C1031 - 3.6v

PLT_RESET_L - no pulse
ALL_SYS_Power_Good - this was strange it might have just been my multimter, Most of the time it would pulseat 5.3v but We watched it for a while ( about 10 pulses) and it would range between 27v - 4v

James
 

2informaticos

Administrator
Staff member
I'm not sure how did you get so high pulses, especially on PCH and CPU coils.

Use SMC mode to check for voltage, if then have 1s fan spining.
Trigger SMC_ONOFF_L and check, without disconnecting power, once entered SMC bypass.
If ALL_SYS_PWRGD and mentioned coils pulse, then check at pins 7 & 3 of U1950 too.
 

LCDR2

Member
Hello

Thank you for your help so far but I am not understanding.

What do you mean by SMC mode? Do You want me to check the coils again in that mode?
How do I Trigger SMC_ONOFF_L ?

Kind regards

James
 

2informaticos

Administrator
Staff member
You've said to get consistent 1s power in SMC bypass.
Once in that mode, do not disconnect charger; machine will remain in that mode when you trigger SMC_ONOFF_L and get another 1s power.
This will help you to measure something.
But, if you note to get the same 1s power in normal mode, do it then.
SMC bypass helps you note when power appears, because of fan spins high.

"How do I Trigger SMC_ONOFF_L?"
You have more than 1 year on the forum, I didn't expect such question...
 

LCDR2

Member
Sorry, I don't do that many board repairs. Maybe 20 a year.

I have tried SMC in bypass mode with no change. i.e. I still get the power pulse and no fan spin.

I will give up on this board for now. Thank you for the help.
 
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