[SOLVED]NO GREEN LIGHT BUT BOOTS+ PPBUS_G3H + PPBUS3v42_G3H PRESENT BUT MAC SLOW

[brooke.j]

Ok so I have a MBA 820-3437 Sometimes I get a green light but it fades. Sometimes I get power and boot but then it will shut off. I've tested for short in diode mode (red on ground)

PPBUS3V42_G3H @ L7095 pin2 =0.309

PPBUS_G3H @ r7006 pin1 = 1.38

Voltage for these two rails are as follows

PPBUS3V42_G3H @ R7005 (BOTH PINS) = 16.5

PPBUS_G3H @ R7006 (BOTH PINS) = 8.56

The Air boots really slow but once booted acts somewhat normal. Maybe just a tad slow but I haven't fixed the or diagnosed the OS yet.

I've reset the SMC and visual inspection of board and caps looks good.

Just looking for direction if there is no green light then what makes the green light? I know it was the one wire circuit before but that is now in the SMC or?
So could PP5V_S4RS3 make the green light.

 

[brooke.j]

OK so it boots everytime. But I get the fading green light. I have to leave it alone for a few minutes before I get the fade. Short? wth?

 

[brooke.j]

Interesting the Mac boots everytime I plug in the power even when the battery is connected. learning some more ..When power pugged in it says 100% but when i unpug it the battery says 87% so am i looking at a charging issue or bad connection with battery.

That would be why when I plug in the power it boots. But it will run off the battery so I'm stumped.

 

[dukefawks]

PPBUS3V42_G3H @ L7095 pin2 =0.309
no way the board would even work then, or are we talking diode mode.

PPBUS_G3H @ r7006 pin1 = 1.38
PPBUS3V42_G3H @ R7005 (BOTH PINS) = 16.5
PPBUS_G3H @ R7006 (BOTH PINS) = 8.56
Makes no sense at all, read what you wrote there.

Most likely bad IO board and/or cable.

 

[brooke.j]

PPBUS3V42_G3H @ L7095 pin2 =0.309
no way the board would even work then, or are we talking diode mode.

PPBUS_G3H @ r7006 pin1 = 1.38
PPBUS3V42_G3H @ R7005 (BOTH PINS) = 16.5
PPBUS_G3H @ R7006 (BOTH PINS) = 8.56
Makes no sense at all, read what you wrote there.

Most likely bad IO board and/or cable.

I don't understand. I said I tested for short in diode mode the readings are: @=measured at
PPBUS_G3H @ r7006 pin1 = 1.38
PPBUS3V42_G3H @ L7095 pin2 =0.309

Oops I did mess up when I said ppbus3v42 on voltage what I was testing for was the line on the other side of 3v42 (PP18V5_DCIN_ISOL_R)

I tested the Voltages and the readings are: BOTH PINS = both side of the resistor.

PP18V5_DCIN_ISOL_R @ R7005 (BOTH PINS) = 16.5v

PPBUS_G3H @ R7006 (BOTH PINS) = 8.56v

PPBUS3V42 @ L7095 PIN2 = 3.4v

 

[brooke.j]

The I/O board tested at the connection to the logic board has

5.1v on pin 3
16.69v on pin 1 and 2

I do have another I/O board but it could be faulty too if that's what the issue is. Still after I leave the computer unplugged for more than 5 minutes when I plug it in the Green light comes on then fades.

Thank you for any isight into what this could be I'm really puzzled and if you need any more information I can take the readings.

 

[dukefawks]

Start with a known good IO board and cable first.

 

[brooke.j]

Wow Rule #1 Known good part. If I could slap myself hard on the back of my head I would. Thx for replying and helping me figure that out.