820-2875 PP3V3_S5_REG missing no green light

Dmitry

New member
I got this board no green light, I figured out that SYS_ONEWIRE was missing, then realized someone already blasted smc with heatgun, I reballed smc, SYS_ONEWIRE returned. PP3V42_G3H_ONEWIRE present
SMC_BC_ACOK 3.3
ADAPTER_SENSE 2.8v


Still no green light, now figured PP3V3_S5_REG missing, somewhere a long the way I replaced U7200.
ENTRIP2 and ENTRIP1 and 5V3V3_REG_EN (0.5v) missing, do I have a case of bad smc? if so is it as simple as finding a same one or I need to anything else with it?

VIN 12v, VREG3 and VREG5 are present on U7200
 

larossmann

Administrator
Staff member
PP3V3_S5 on most boards is controlled by SMC. If you still don't have green light we can't do anything with PP3V3_S5 yet. If the board was previously blasted with heatgun to SMC, then likely the SMC is damaged/dead, so needs replacing. Get green light first. Then go for everything else!

is there reason why I dont get any answers?

Yes, you posted this 3 hours ago. Instant replies are available for additional $1k/mo/member.

You gave number for an iPad 2, but are giving rails/signals for a Macbook. What board are we working with here?
 

Dmitry

New member
PP3V3_S5 on most boards is controlled by SMC. If you still don't have green light we can't do anything with PP3V3_S5 yet. If the board was previously blasted with heatgun to SMC, then likely the SMC is damaged/dead, so needs replacing. Get green light first. Then go for everything else!



Yes, you posted this 3 hours ago. Instant replies are available for additional $1k/mo/member.

You gave number for an iPad 2, but are giving rails/signals for a Macbook. What board are we working with here?

820-2879 is the right number, so after smc replacement do I have to flash anything? I dont have much experience with macbooks, but with regular laptops I need to flash it some time when replacing multi-controller. is that the case with macbooks?
 

2informaticos

Administrator
Staff member
Does something change on the symptom?
Give us some voltages on the board.
Did you get green light?
Help us to help you...
 

Dmitry

New member
Does something change on the symptom?
Give us some voltages on the board.
Did you get green light?
Help us to help you...

I gave the voltages in my first post. nothing was changed , Louis kind of confirming that my smc probably bad and I asked if it is as simple as installing new one, or I have to flash/reset anything.
 

larossmann

Administrator
Staff member
No flash/reset. If SMC_RESET_L is high, then you can go ahead and replace SMC. Must be taken from another 820-2879 of course.
 

2informaticos

Administrator
Staff member
Posted voltages are insufficient.
BTW "VIN 12v" is useless.
PPBUS_G3H is 12.3V, or 12.55V; the exact value will tell us a lot!
Do you have voltage at L7750?
Also measure U7840 and U5010.
ADAPTER_SENSE and SYS_ONEWIRE should have the same value; only you can measure...
Check if central pin of magsafe has the same voltage too.
 

Dmitry

New member
No flash/reset. If SMC_RESET_L is high, then you can go ahead and replace SMC. Must be taken from another 820-2879 of course.

SMC_RESET_L - is high (3.4v),

I didnt find 820-2879 for reasonable price on ebay, But i do have 820-2936 that I got from ebay for $30, it has the same smc code, so I tried that on my board since it looks like last chance for repair.

After replacement of SMC few things has changed.
green light on
PP3V3_S5_REG is present now
SMC_RESET_L - is high (3.4v) still high

u7200
=P5VS3_EN_L- low
ENTRIP2 - 0.7v
3V3S5_VBST - is 8v wtf ?

PP5V_S3_REG missing , why dont u7200 generate it?

Vin is present, P5VS3_EN_L is low, what else? or it is
 

2informaticos

Administrator
Staff member
Pretty sure that SMC will not work there.
You swapped one from PCH platform to MCP (nVidia).
It must be from same 820-2879.
BTW, any x_EN_L signal should be low for working...
And that BST voltage is OK; learn how a buck converter works.
 

dukefawks

Administrator
Different SMC firmware need to take from identical board. At least you know the original SMC is bad. Also these board do not auto power on, need to short the power pads.
 
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