820-3330-B Not powering On

[techgeeksna]

Good Day , ive got a A1268 820-3330-B board here. The computer was working fine and the next morning refused to turn on. The green led on charger lights up for about a minute then goes off. The computer wont switch on from power or from battery.

so far ive measured the following.

PPDCIN_G3H - 16.2V
PPBUS_G3H - 12.6V

could anyone please point me in the right direction.

P.S Yes im using 85w charger and yes its the original charger.

 

[dukefawks]

Does it power from a charged battery? Known good magsafe board? ACOK present?

 

[techgeeksna]

Good Day Duke, does not power from charged battery, yes known good magsafe board. ACOK 2.2V

 

[dukefawks]

ACOK is too low. Check things around U7000, the usual pins 17/18, 27/28, R7005.

 

[techgeeksna]

U7000 pin 17&18 is 12.6V Pin 27/28 is 18V R7005 - 18v

 

[techgeeksna]

Sorry about that , here goes pin
17/18 - 3 ohms
27/28 - 20 ohms
R7005 - 20 ohms

 

[dukefawks]

Check SMC_BC_ACOK again, that 2.2V is not right.

 

[techgeeksna]

HI, SMC_BC_ACOK IS 2.3V AT U7000 PIN 14.
At R5393 its 3.4v

 

[dukefawks]

Is R5393 on the board?

 

[techgeeksna]

No its not.

 

[techgeeksna]

the 3.4v measurement i got by testing pin 1 of r5393.

 

[techgeeksna]

thanks i will check that, im in a completely different time zone, which means when your awake im asleep and vice versa. Do you perhaps have any other ideas i can try if the trace happens to be good? im currently using another board that does power on to test different points and i also get the low voltage ACOK at pin 14 of ISL. 2.3v/2.4v.

Like i mentioned in my initial posting the computer was working perfectly fine and just died the next morning. No signs of liquid damage and no physical damage either.

 

[techgeeksna]

Good Day, a short update. pin 14 and pin 1 of r5393 are same voltage and the trace is good. So im still stuck with a board with no green or orange LED.

 

[dukefawks]

So is that same voltage 2.4 or 3.3V now?

 

[techgeeksna]

Good Day 2.4V at both points

 

[dukefawks]

That is no good. What is resistance to GND on that line? R5087 checked?

 

[techgeeksna]

R5087 checked - 469K
resistance to ground on SMC BC ACOK is 737K,ohms

 

[dukefawks]

Well, the first suspect would be the 6259 at this point and if it all sucks then the SMC.