baker_jeff
Member
Hello all! I've been buying and fixing MacBooks (everything up to dead boards) since the fall and my pile of units needing board repairs is growing quite high. I've had all the equipment for about 6 weeks and I've decided it's time to get off my ass and learn. I have been watching videos and read the Training Guide (thanks Louis) for the last couple months, but hot damn it's a lot to absorb.
My first board I'm going to learn on is a Late-2008 MacBook, 820-2327-A. The Magsafe light comes on green, but the board won't boot. I did find one burnt cap relating to "GND_CHASSIS_AUDIO to MIC_LO_CONN_F" so far, but I'm assuming that won't affect my power issues?
I used the schematic and openboardview to find the F7000 fuse, and it is getting 12.6v on each side, followed it to "R7008" also getting 12.6v, "C7008" also getting 12.6v one one side and 0 on the side indicated as ground...
It was suggested to me, "Alright. So you do have PPBUS.. Probably will be missing a 3.3 or 5 v rail. Lets start with s5. PP3v3_s5 amd PP5v_S5.. check both those"
I stuck "PP3v3_s5" into the schematic and searched until I found a page which feels relevant (Page 58)
I looked up C7251. Pin 1 is PP3V3_S5, pin 2 is ground. Volt meter detects 0v on Pin 1. Continuing.
I looked up C7252, which is located right above the previous cap. Pin 1 again is PP3V3_S5, and is showing 0 volts.
I'm following the lines on the schematic pretty blindly and guessing, forgive me....
So the next thing I'm guessing about is C7220. Pin 1 shows 0v. Pin 2 shows 4.78v.
I have a working same unit here, so I measured C7220 on the working board. Pin 1 shows 3.3v, Pin 2 shows 7.8v. So I'm not getting enough voltage to C7220 on the dead board.
I checked C7272. Pin 1 is PPBUS_G3H and is showing 12.58v. Pin 2 is ground.
Looking at chip U7200, voltage going into pin 16 is also 12.58v.
Tracing the line from the components tested earlier, it looks like the voltage should be coming out of Pin 11 on U7200? I'm measuring 0 volts from this pin. Could this chip be the problem?
Am I on the right track or totally out to lunch?
Thanks!
My first board I'm going to learn on is a Late-2008 MacBook, 820-2327-A. The Magsafe light comes on green, but the board won't boot. I did find one burnt cap relating to "GND_CHASSIS_AUDIO to MIC_LO_CONN_F" so far, but I'm assuming that won't affect my power issues?
I used the schematic and openboardview to find the F7000 fuse, and it is getting 12.6v on each side, followed it to "R7008" also getting 12.6v, "C7008" also getting 12.6v one one side and 0 on the side indicated as ground...
It was suggested to me, "Alright. So you do have PPBUS.. Probably will be missing a 3.3 or 5 v rail. Lets start with s5. PP3v3_s5 amd PP5v_S5.. check both those"
I stuck "PP3v3_s5" into the schematic and searched until I found a page which feels relevant (Page 58)
I looked up C7251. Pin 1 is PP3V3_S5, pin 2 is ground. Volt meter detects 0v on Pin 1. Continuing.
I looked up C7252, which is located right above the previous cap. Pin 1 again is PP3V3_S5, and is showing 0 volts.
I'm following the lines on the schematic pretty blindly and guessing, forgive me....
So the next thing I'm guessing about is C7220. Pin 1 shows 0v. Pin 2 shows 4.78v.
I have a working same unit here, so I measured C7220 on the working board. Pin 1 shows 3.3v, Pin 2 shows 7.8v. So I'm not getting enough voltage to C7220 on the dead board.
I checked C7272. Pin 1 is PPBUS_G3H and is showing 12.58v. Pin 2 is ground.
Looking at chip U7200, voltage going into pin 16 is also 12.58v.
Tracing the line from the components tested earlier, it looks like the voltage should be coming out of Pin 11 on U7200? I'm measuring 0 volts from this pin. Could this chip be the problem?
Am I on the right track or totally out to lunch?
Thanks!
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