820-3476-a Power no display

[2informaticos]

60/85W Magsafe 2 charger for sure?

 

[Anterweb]

Oh ffs, what a noob I am !
Plugged in an 85w mag and of course the fan starts to spin, also just noticed while trying this again back in the mac adding one cable at a time that no matter what is connected and regardless of running on magsafe or battery when you turn it off by holding the power button after a couple of seconds it seems to power itself on again and the fan starts spinning and keeps spinning until I hold the power button down and disconnect the battery and the magsafe.

 

[Anterweb]

Also just tried to boot in smc bypass, I get full fan spin but still no display on external or internal screen.

 

[2informaticos]

Do all mentioned checkings...

 

[Anterweb]

ppbus_g3h - 12.53V
PP3V42_G3H - 3.41V
PPVRTC_G3H - 3.33V
PP5V_S5 - 5V
SMC_LID - 3.41V
PP3V3_S5 - 3.31V

All the same as before

coils

L7130 = 12v
l7520 = 4.86v
l7560 = 3.25v
l3095 =0v
l7430 =1.369v
l7320 =1.7v
l3310 =1.7v

PLT_Reset_L = 0v

U1950 pin 7 = .526v
pin 3 = goes crazy between .526v and 190.0mv

All_sys_pwrgd =3.32v

 

[2informaticos]

Don't you get 3V at pin 2/U1950?

Remove U1950 and check its pads and board traces.

 

[Anterweb]

OK removed U1950 noticed that C1950 looked slightly corroded and it looked like a break in the trace , Removed C1950 and made sure I had repaired the trace getting 3v to pin 8,

I got 3V at pin 2/U1950 now,

But... I have blown U3560 into the abyss! ( How important is this? ) can I work without it or is this another board for parts bin?

 

[2informaticos]

It should work without it.
You probably don't need AP, or PCIE wake function.
You can place R3560, for AP wake...

 

[Anterweb]

Ahh, That's cool! But even after getting correct voltages on U1950 I'm still getting fan spin, cpu gets warm but no beep no display,

It's yet another one I feel that has beaten me

 

[2informaticos]

Do you get 3V at pin 3/U1950?
Also check CPU coils and PLT_RESET_L.

 

[Anterweb]

"Do you get 3V at pin 3/U1950?" = yes

CPU Coils both at 1.7v

PLT_RESET_L = 0v

I also just noticed that since cleaning up U1950 I no longer get a constant fan spin but what seems to be power cycling , on for a few seconds then off for a few then back on again etc etc same for both voltages and fan spins .

 

[2informaticos]

Check CPU_VCCST_PWRGD and CPU_VR_READY.
Also check presence for all voltages on page 11.

There are many power rails to check on pages 59 & 60 too.

Just in case, try turning on in SMC bypass mode.

 

[Anterweb]

CPU_VCCST_PWRGD = 1.047v
CPU_VR_READY = 1.052v
Page 11 , 59 & 60 all voltages present ( that took cooking ages! )

SMC Bypass samer shit,

I can't see any reason this shouldn't power up and play, But fan spin and cpu getting warm is all we get.

 

[2informaticos]

Is the board power cycling now?

Try known good BIOS...

 

[Anterweb]

Power cycling seems to have stopped or only happens after long periods of being turned on when testing voltages,


I'm currently in the process of ordering a Medusa ( And a pile of Tiresias (the GPUkiller) chips ) from Harald but he is currently on vacation until the 23rd of june

Without a Medusa would I need to remove the bios chip to try good bios? Or am I best of waiting till the Medusa arrives?

( Also I notice there are 3 different versions of the Medusa what version would you recommend I get?

 

[2informaticos]

I don't know if Harald has newer version than 3, for Medusa.
I got version 2 long time ago and still does the things I need.
Probably is better to get version 3, or which one is latest.
Be sure to get all necessary adapters, to connect all kind of boards and single chips.
He has in stock some board adapters with 1.8V support.

I'm still pending to test his battery port tester, received few weeks ago.

Is not dificult to flash SPI chip outside of the board, using cheapest CH4341, or other programmer.

 

[Anterweb]

Spoken to Harald, I have to wait until he is back from vacation ( 23rd) before I can put an order in so going to try removing bios chip and using my cheap programmer.

I've just tyred searching the board for a clean ME bios for this board but don't see one posted recently. Would you have a good bios file I could try please?

Also could you give us your feedback on the battery port tester when you have had a chance to try it out.

 

[2informaticos]

820-3476-Working-CleanME.bin

drive.google.com

Try this file as is, don't change serial number.
If works, then change serial and fix checksum.

 

[Anterweb]

Managed to get back to this one today.

Tried your bios and same shit sadly,

Powers on, cpu gets warm no display on internal or external display.

 

[2informaticos]

PLT_RESET_L still low?