MacBook Pro A1286 Mid 2012 no power, no LED on the charger

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Okay I was able to find another cable separate from a display, connected it and powered on. Chimed and video showing on external monitor.

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Ok. But I meant to ask if the laptop LCD has a removeable cable - if yes, consider to remove this cable and attach to the logic board only.

This is to confirm if there is a possible short in the LCD cable.

With the LCD connected, measure the voltages on the LCD connector J9000.

Post the readings.

Do confirm that the following EMI filters are still present and not broken:

L9010

L9011

Voltage readings of:

LVDS_DDC_CLK ?
LVDS_DDC_DATA ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Ok. But I meant to ask if the laptop LCD has a removeable cable - if yes, consider to remove this cable and attach to the logic board only.

This is to confirm if there is a possible short in the LCD cable.

With the LCD connected, measure the voltages on the LCD connector J9000.

Post the readings.

Do confirm that the following EMI filters are still present and not broken:

L9010

L9011

Voltage readings of:

LVDS_DDC_CLK ?
LVDS_DDC_DATA ?

Hi mon2,

No I could not remove the cable from this LCD but I had a spare LVDS cable that I connected to the logic board without any LCD connected. And I heard chime and saw video on external monitor connected by HDMI.

L9010 showing .000 on 2V mode on all pins. L9011 showing .000 on 2V mode on all pins.

LVDS_DDC_CLK showing .000 on 2V mode.
LVDS_DDC_DATA showing .000 on 2V mode.

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Voltage on pins 2&3 of lcd connector?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Voltage on pins 2&3 of lcd connector?

Showing .002 on 2V mode.

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

So the LCD is not being powered which explains why it is dark & no video.

See attached. Measure and post the readings for the power rail regulator for the LCD.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

LCD_PWR_EN on R9094 measured .012 on 2V mode.

PP3V3_S5_LCD on C9009 measured 3.32 on 20V mode.

PP3V3_SW_LCD on C9002 measured 00.5 on 200m mode, .000 on 2V mode.

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

What is the voltage of PP3V3_S0_DDC_LCD (measure @ R9010 / R9011 - pin # 1).

LVDS_DDC_CLK showing .000 on 2V mode.
LVDS_DDC_DATA showing .000 on 2V mode.

Power down and remove the LCD - what is the voltage for the above 2 lines without the LCD attached ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

What is the voltage of PP3V3_S0_DDC_LCD (measure @ R9010 / R9011 - pin # 1).




Power down and remove the LCD - what is the voltage for the above 2 lines without the LCD attached ?

PP3V3_S0_DDC_LCD measured at R9010 showing 3.3V with 20V mode.

LVDS_DDC_CLK showing 3.3V with 20V mode, without LCD connected.

LVDS_DDC_DATA showing 3.26V with 20V mode, without LCD connected.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Sorry might have misunderstood before.

LVDS_DDC_CLK showing 3.3V with 20V mode, with LCD connected.

LVDS_DDC_DATA showing 3.26V with 20V mode, with LCD connected.

Before I was showing resistance to ground with machine power removed.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Something interesting I did find by accident.

R9678 on pin 2 showing 2.64 on 20V mode. Pin 1 on R9678 showing .012 on 2V mode. With power on and LCD connected.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Hi mon2, is the above at all useful?

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Remove all power. Meter in lowest resistance scale.

Measure the resistance to ground of each pin on the lcd connector with the lcd connected.

If the meter shows '1' or 'OL' then use the next higher resistance scale till the resistance value is measured.

Post the readings. The list from yesterday does not make sense since it on the voltage scale.

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Remove all power. Meter in lowest resistance scale.

Measure the resistance to ground of each pin on the lcd connector with the lcd connected.

If the meter shows '1' or 'OL' then use the next higher resistance scale till the resistance value is measured.

Post the readings. The list from yesterday does not make sense since it on the voltage scale.

Pin 1: 01.2 on 200 scale
Pin 2: 1.952 on 2k scale
Pin 3: 1.952 on 2k scale
Pin 4: .0743 on 2k scale
Pin 6: .661 on 2k scale
Pin 7: 1.811 on 2k scale
Pin 8: 1.815 on 2k scale
Pin 9: 1.739 on 2k scale
Pin 10: 0.01 on 2k scale
Pin 11: .462 on 2k scale
Pin 12: .462 on 2k scale
Pin 14: .461 on 2k scale
Pin 15: .461 on 2k scale
Pin 17: .462 on 2k scale
Pin 18: .463 on 2k scale
Pin 20: .462 on 2k scale
Pin 21: .464 on 2k scale
Pin 23: .462 on 2k scale
Pin 24: .469 on 2k scale
Pin 26: .461 on 2k scale
Pin 27: .463 on 2k scale
Pin 29: .463 on 2k scale
Pin 30: .913 on 2k scale
Pin 31: shows 1. on every scale up to 2M
Pin 32: shows 1. on every scale up to 2M
Pin 33: shows 1. on every scale up to 2M
Pin 34: shows 1. on every scale up to 2M
Pin 35: shows 1. on every scale up to 2M
Pin 36: 1.418 on 2k scale
Pin 38: 0.705 on 2K scale
Pin 39: 0.705 on 2K scale
Pin 40: 0.705 on 2K scale

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Pin 4: .0743 on 2k scale

this looks to be low. can you lower your meter scale to 200 ohms and measure this rail again ?

Is this 74R3 = 74.3 ohms to ground ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

this looks to be low. can you lower your meter scale to 200 ohms and measure this rail again ?

Is this 74R3 = 74.3 ohms to ground ?

Showing 1 on 200 ohms. Measured again on 2k scale and showing .307.

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Ok. Ignore for now.

Pin 30 is showing a different reading than pin 29 on the LCD connector.

Can you measure @ L9011 - pins 4 & 1 ? What are the readings at this junction ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Pin 1: .461 on 2k mode
Pin 4: .461 on 2k mode

[mon2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Now check again AFTER this part so pins 3 & 2. What are the readings ?

[Gigabit2]

Re: MacBook Pro A1286 Mid 2012 no power, no LED on the charger

Pin 2: .459 on 2k mode
Pin 3: .461 on 2k mode