A1466 /?820-00165 - power rails but no fan spin

acowan

Member
Hi

Bit of a noob here so please excuse the no doubt dumb questions.

I?ve been working on fixing a A1466 / 820-00165 Mac Book Air and I?ve got to the point where the main power rails are looking correct but I?m not sure where to go from here. I'm getting a green then organ light from the charger but no fan spin when powered.

Measured voltages:

PP3v3_s5 = 3.336
PP3V3_G3H = 3.401
PP3V3_SUS = 3.336
PPBUS_G3H = 8.589
PP5V_S5 = 5.014
PP5V_S4RS3 = 0.0012
PP5V_S0 = 0.00

Am I expecting PP5V_S0 or PP5V_S4RS3 as soon as the power connector is plugged in? or do I need to hit the keyboard power button. I notice in Louis? videos he never seems to have a keyboard plugged in or ?do anything? to initiate boot up

Any help much appreciated.
 

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

All iCore boards should start automatically when charger is connected, if no battery present.
Try the board itself, disconnecting LIO flex, airport card, internal SSD and trackpad.

Be sure to use original Magsafe 2 charger; post PM_BATLOW_L level.

Also post PM_DSW_PWRGD, PCH_DSWVRMEN, PM_RSMRST_L and PM_PAWRBTN_L.
Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
If present, check for pulse at all PM_SLP_Sx_L signals at same time.
 

acowan

Member
Hey there thanks very much!

Here are some voltages after a bit of probing. Annoying the damn fan started spinning during the probing, then stopped.

PM_BATLOW_L = 3.331v
PM_DSW_PWRGD = 3.341v
PCH_DSWVRMEN = 3.002v
PM_PWRBTN_L = 3.4003v
PM_RSMRST_L = 2.734v

My scope is otherwise engaged for the next few hours but it looks like PM_SLP_S4_L is pulsing - difficult to see the frequency on a 8808 but looks like every second or so.
 

2informaticos

Administrator
Staff member
All PM_SLP_Sx_L signals should pulse then.
Check for pulse at all big coils, if fan spins.

No need of o-scope.
Repeatedly trigger SMC_ONOFF_L and check for pulses...
 

acowan

Member
Yup .. so all PM_SLP_Sx_L lines all pulse to 3.2v every 4.2 seconds, the pulse width is about 200ms

By triggering the SMC_ONOFF_L just pull it to ground?
 

2informaticos

Administrator
Staff member
You must simulate power button; do NOT maintain SMC_ONOFF_L to ground, just do temporary contact.

So you are in 5s cycling power loop.
Do you get pulse at L7310/20 too?
What about pins 7 & 3 of U1950?
 

acowan

Member
Yup looks like a power loop to me!

Pulse at L7320
CPUVR_PHASE2 = 8.5v
PPVCC_S0_CPU_PH2 = 1.75 (ish)

Pulse at L7310
CPUVR_PHASE1 = 8.5v
PPVCC_S0_CPU_PH1 = 1.75 (ish)

U1950
PIN 3 - SYS_PWROK = pulsing
PIN 7 - PM_S0_PGOOD = pulsing
PIN 2 - CPUVR_PGOOD = pulsing
PIN 1 - ALL_SYS_PWRGD = pulsing
 

acowan

Member
History wise, no idea, an acquired laptop :) Given to me with no more than the words 'it doesn't work'.

The inside didn't look messed with, judging by the thick layer of dust. The only thing that looked corroded out of place was a bit of corrosion at J6100.

Just working out how to start in SMC bypass mode now
 

acowan

Member
Ok - I give up. Lots of mentioned of people saying they did start up in bypass mode but I cant find out how to do it.

How exactly does one start up in SMB bypass mode?

Did I say I was vanilla / a noob / pure with this ?
 

2informaticos

Administrator
Staff member
Press power button (use the same wire from SMC_ONOFF_L), connect charger, mantain pressed and release it after 5-10s.

I suppose you don't have Medusa programmer, so I recommend to remove J6100.
Check all SPI Bus Series Termination resistors and their traces; page 46, more than 20 resistors.
If all good, try known good BIOS file (U6100).
 

acowan

Member
Removing J6100 seems to have sorted it - I should have really just removed/replaced it when I first noticed the corrosion.

Thanks for your help with this. Much appreciated - can I get you a beer as a thank you somehow?
 

acowan

Member
Well just tried to send you a pvt message with some beer information - but you have exceeded your "private message quota" according to the ever knowing vBulletin
 

2informaticos

Administrator
Staff member
I just made space on Inbox.
However, PM doesn't help too much, as I can only receive a truncated message in my eMail.
I cannot read entire PM on the forum...
 
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