820-2523-B Mid 2009 15" MacBook Pro hot U7201

[Melvinzill]

Hi, having some Problems with this mid 09 board. It was at a different shop before as the backlight didn't work and they told the customer they couldn't fix it. I actually had a talk with that other place and they said they used freeze spray to find the issue causing the backlight issue and and that killed the board. Incredibly shady...

Well anyway, the board did have some corrosion which could either be liquid damage or maybe from the freeze spray they used....

The board has a green light, PP3V42_G3H, PPBUS_G3H but the S5 rails appear to already be missing. The main thing I noticed was U7201 getting very hot. Already replaced it with another one thinking it might be bad but that didn't help...


Anyone got a clue? I know these older boards aren't all that common for repair nowadays but maybe someone had an issue like this before...

 

[2informaticos]

U7201 still hot?
Post its basic voltages; pins 16, 13, 3, 8, 17, 6, 1.
Check diode mode at pins 8, 17 and L7220/60.
Do you get voltage at L7260 and L7770?

 

[Melvinzill]

So:

U7201 Voltags:
Pin 16: 12.66V
Pin 13: 3.357V
Pin 3: 2.040V
Pin 8: 4.746V
Pin 17: 0.8V
Pin 6: 0V
Pin 1: 0V

Diode Mode:
Pin 8: 0.010
Pin 17: 0.007
L7220: 0.422
L7260: 0.106

Voltage at L7260: 0V
Voltage at L7770: 0V

Note I did these measurements straight after plugging in the board without pressing the power button. I don't know if that would make a difference. One thing I sure about the C2D board is that they don't auto boot after being plugged in

 

[2informaticos]

Allow 10-15s after power is removed, before measure diode mode.

Remove C7205 and check again diode mode at pin 17.
Very strange voltage at pin 8; try another chip.
Once chip is removed, check diode mode at pins 8 & 17.