820-3208 not turning on

BCN_Techs

Member
Air 820-3208 logic board with all rails present.


PP1V05_S0 Seems to be shorted to ground. When trying SMC BYPASS mode fan tries to spin but stop immediatly.


Checked all PP1V05_S0 circuit components with few resistors with wrong value. Changed them, but there is no change. Can't find where the short is.
 

JohnB8812

New member
Ok so no VCore means something is indeed missing and in this case 1v05. I?d say inject voltage and see what heats up. Start lower voltage wise like 0.5 volts
 

BCN_Techs

Member
will try to buy freeze spray. But how it's possible that injecting i get the voltage and with magsafe it's shorted?
 

JohnB8812

New member
You're measuring resistance with power applied??? I hope not as that's a great way to ruin your multimeter.....
 

BCN_Techs

Member
No, I only measure Voltage. And that is what i cant understand. If it is shorted it must be shorted by magsafe or injecting directly to rail. right?
 

2informaticos

Administrator
Staff member
There is no short; STOP to inject voltage without reason.
Did you compare same power rail with a good board???
12 ohms is normal value for PCH core!
 

JohnB8812

New member
12 ohms seems kinda low for that board, but yeah if you're measuring for a short with power applied, that's going to cause issues.
 

BCN_Techs

Member
There is no short; STOP to inject voltage without reason.
Did you compare same power rail with a good board???
12 ohms is normal value for PCH core!

No informaticos. I dont have another board to compare. I compared it with other board same rail and tester is not beeping with ground. Any idea?
 

2informaticos

Administrator
Staff member
Different values, for VCORE and 1V05 power rails, depending what chips used in each board.

3023 uses Cougar Point PCH and Sandy Bridge CPU.
015 / 007.

3024 same as 3023
008 / 017.

3208 uses Panther Point PCH and Ivy Bridge CPU.
*not available to test*

3437 uses Haswell-ULT (intel MCP).
040 / 090.

00165 uses Broadwell-ULT (Intel MCP).
010 / 140.

All values in diode mode, red probe to ground; VCORE / 1V05 rails.
Values vary from board to board (even same model), and depends by multimeter and CPU type (i3-5-7)...
BTW, I got them from non-working boards; but no short detected anywhere.
 

2informaticos

Administrator
Staff member
Post some voltages for U7600; pins 13, 14, 3.
Be sure all traces, solders and surrounding components are good.
 

BCN_Techs

Member
Pin 3,13,14 - 0V


I noticed that C7602 and C7601 have very smal burn on pin 1. Will change them tomorrow and tell you result here. Thanks
 
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