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820-2936 Fan turn on and off cycling, no orange LED when connected to battery
- Thread starter protocold
- Start date
Use 60/85W Magsafe 1 charger and post some basic voltages.
I am using 85w. I noticed there is some corrosion around Q5300. R5301 went missing and the traces going to pin 4 of Q5300 is broken/corroded.
Checked Pin 4 is still connected to PPBUS_G3H = 12.48v until fan is stopped...
I replaced Q5300 and also re-solder 100k between pin 4 and pin 5, it is still the same...
Q5300 pin 3 is 12.48v until fan stop and cycling.
ALL_SYS_PWRGD pulses 3.3v
L7510/20 = pulse 1.14v
L7550 = PPVCORE_S0_AXG_L = 0v.
Q7550 pin 1 pulse 12.6v, pin 4 = U7400 pin 12 = shorted to ground.
U7400 voltage; pins 15,24,40 = pulse 5v, pin 1 = pulse 3.3v , pin 2 = pulses all over the place.
Checked Pin 4 is still connected to PPBUS_G3H = 12.48v until fan is stopped...
I replaced Q5300 and also re-solder 100k between pin 4 and pin 5, it is still the same...
Q5300 pin 3 is 12.48v until fan stop and cycling.
ALL_SYS_PWRGD pulses 3.3v
L7510/20 = pulse 1.14v
L7550 = PPVCORE_S0_AXG_L = 0v.
Q7550 pin 1 pulse 12.6v, pin 4 = U7400 pin 12 = shorted to ground.
U7400 voltage; pins 15,24,40 = pulse 5v, pin 1 = pulse 3.3v , pin 2 = pulses all over the place.
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U7400 is bad, if has short to ground at pin 4.
Short on pin4 of U7400, or Q7550?
If on Q7550, what is ohm value of the short?
If on Q7550, what is ohm value of the short?
CPU coils may have very low resistance to ground as normal.
You can compare eith good board.
I suppose you don't have any short there.
Did you try to start in SMC bypass mode?
Just in case, replace R7402 and check its traces and solder to pin 2/U7400.
You can compare eith good board.
I suppose you don't have any short there.
Did you try to start in SMC bypass mode?
Just in case, replace R7402 and check its traces and solder to pin 2/U7400.
What is CPU voltage after 10s?
Did you try more DDR3 memory modules?
If machines stays on in SMC bypass, then you have problems with a SMC sensor.
Check first AVREF_SMC voltage.
Did you try more DDR3 memory modules?
If machines stays on in SMC bypass, then you have problems with a SMC sensor.
Check first AVREF_SMC voltage.
VCORE should drop around 0.75V when board really boots.
In SMC bypass the fan should spin continuosly to max speed.
Take a look at the circuitries from pages 49 & 50.
Your starting problem is related with one I/V sensor.
Check their output voltage in SMC bypass mode.
In SMC bypass the fan should spin continuosly to max speed.
Take a look at the circuitries from pages 49 & 50.
Your starting problem is related with one I/V sensor.
Check their output voltage in SMC bypass mode.
SMC_CPU_VSENSE = 0.65 - 0.95 fluctuate
SMC_CPU_ISENSE =0v
SMC_GFX_VSENSE = bouncing 0 - 0.7v
SMC_GFX_ISENSE = 0v
TP_SMC_P1V5S3_ISENSE = 0.27v
SMC_CPUVCCIO_ISENSE = 0v
TP_SMC_SA_ISENSE = unknown test point location
SMC_DCIN_VSENSE = 2.82v
SMC_DCIN_ISENSE = 2.1v and when lifting multimeter it will shut down
I will measure the rest later today but is anyone of the above look suspicious so far?
SMC_CPU_ISENSE =0v
SMC_GFX_VSENSE = bouncing 0 - 0.7v
SMC_GFX_ISENSE = 0v
TP_SMC_P1V5S3_ISENSE = 0.27v
SMC_CPUVCCIO_ISENSE = 0v
TP_SMC_SA_ISENSE = unknown test point location
SMC_DCIN_VSENSE = 2.82v
SMC_DCIN_ISENSE = 2.1v and when lifting multimeter it will shut down
I will measure the rest later today but is anyone of the above look suspicious so far?
Check resistance (ohm scale) between pins 17/18 and 27/28 of U7000.
"17/18 = 20 ohm"
You should get 2 ohm aprox there.
You should get 2 ohm aprox there.
ya i know from schematics R7050 + R7051 + R7052 should be 2.21ohm..
let me get a new multimeter, as now it is measuring 10.x ohm..
There is a glue blob around R7052 but I saw brownish shadow within it near R7052 pin2 .. when I cut open the glue blob I confirmed that pin 2 of R7052 was probably heated up somehow that causes burn mark on the surrounding glue.. now R7052 measured around 7.9 ohm between pin 1 and pin 2. R7051 measured around 3.0 ohm (however between the 2 pole or any 2 screws the multimeter read 0.9ohm, assuming this is internal resistance between the 2 pole). I guess subtracting that from 3.0 will give 2.1 ohm which means R7051 is probably OK.
I measured R7050 and it is also 0.9 ohm. again subtracting the internal resistance should be 0 ohm, which also means R7050 is ok.
This implies R7052 is messed up?
let me get a new multimeter, as now it is measuring 10.x ohm..
There is a glue blob around R7052 but I saw brownish shadow within it near R7052 pin2 .. when I cut open the glue blob I confirmed that pin 2 of R7052 was probably heated up somehow that causes burn mark on the surrounding glue.. now R7052 measured around 7.9 ohm between pin 1 and pin 2. R7051 measured around 3.0 ohm (however between the 2 pole or any 2 screws the multimeter read 0.9ohm, assuming this is internal resistance between the 2 pole). I guess subtracting that from 3.0 will give 2.1 ohm which means R7051 is probably OK.
I measured R7050 and it is also 0.9 ohm. again subtracting the internal resistance should be 0 ohm, which also means R7050 is ok.
This implies R7052 is messed up?
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