gregwtmtno
New member
Hi,
I'm a total novice at this stuff so please be patient. I took apart a working non-unibody MacBook Pro 15 inch (probably vintage at this point) to reapply the thermal paste and to blow out the dust. When I tried to turn it back on, I got a green light on the charger and the HD spins up, but no fan spin or display.
After investigating, I found that I have all S0 rails except for PP1V5_S0. As best I can tell from the schematic, the rail should be generated by U7600. I measured voltages around there, and things definitely look a bit off, but I'm not sure what they should be. (I’m not able to measure directly on the chip—instead I’m measuring at a different component, hopefully nearby, but sometimes on the other side of the board. Should I be trying to measure at the chip itself?)
For those measurements, I get:
U7600 voltages (clockwise)
Some of these values look suspicious to me, especially TRIP, TON, and VBST, but I don’t know what they should be.
Also, the problem seems to be intermittent to a point. After measuring these voltages, I was surprised to find that the laptop screen came on the next time I connected the power cord. However, I wasn’t able to get it to happen twice. I wonder if it has something to do with the heat of having the board on for a while as I was taking measurements.
Thanks very much for any guidance at all you can give me!
Greg
I'm a total novice at this stuff so please be patient. I took apart a working non-unibody MacBook Pro 15 inch (probably vintage at this point) to reapply the thermal paste and to blow out the dust. When I tried to turn it back on, I got a green light on the charger and the HD spins up, but no fan spin or display.
After investigating, I found that I have all S0 rails except for PP1V5_S0. As best I can tell from the schematic, the rail should be generated by U7600. I measured voltages around there, and things definitely look a bit off, but I'm not sure what they should be. (I’m not able to measure directly on the chip—instead I’m measuring at a different component, hopefully nearby, but sometimes on the other side of the board. Should I be trying to measure at the chip itself?)
For those measurements, I get:
U7600 voltages (clockwise)
Line Label | Pin Num | Measured On | Voltage |
PP5V_S5 | 10 | C7600, pin 1 | 4.96 |
P1V5S0_TON | 2 | R7619, pin 1 | 0.08 |
P1V5S0_VBST | 14 | R7615, pin 1 | 4.5 |
P1V5S0_DRVH | 13 | Q7620, pin ? | 12? |
P1V5S0_LL | 12 | L7620, pin 1 | 0 |
P1V5S0_DRVL | 9 | Could not measure | |
GND | 7 | R7611, pin 2 | 0 |
GND | 15 | R7611, pin 2 | 0 |
GND | 8 | R7611, pin 2 | 0 |
P1V5S0_TRIP | 11 | R7605, pin 1 | 0.6 |
P1V5S0_VFB | 5 | R76111, pin 1 | 0 |
PP1V5_S0 | 3 | L2700, pin 1 | 0 |
P1V5P1V05S0_PGOOD | 6 | U7880, pin 1 | 0 |
PM_SLP_S3_DELAY_L | 1 | U7850, pin 4 | 3.27 |
PP5V_S5_P1V5S0_V5FILT | 4 | R7601, pin 2 | 4.9 |
Also, the problem seems to be intermittent to a point. After measuring these voltages, I was surprised to find that the laptop screen came on the next time I connected the power cord. However, I wasn’t able to get it to happen twice. I wonder if it has something to do with the heat of having the board on for a while as I was taking measurements.
Thanks very much for any guidance at all you can give me!
Greg