Macbook A1932 Intermittent Backlight Issue 820-01521

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Can you share the meter setting?

If you short your meter probes, do you see the same resistance readings?

FINAL UPDATE.
Replaced the Fuse F6700 yesterday and the trackpad started giving very light haptic feedback. Today morning it is giving proper haptic feedback but the backlight issue is back again.

Removed the Fuse F6700.
Voltage at Pin 1 is 12.6V and Resistance to Ground at Pin 1 is 470.

After Removing the Fuse, the Backlight Issue is fine but the Haptic is Gone Again.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

FINALLY
We ahead and replaced the R5610 and L6700 both connected to the Fuse F6700. See Attached
Now there is no Intermittent Backlight issue or Trackpad Haptic Issue. Will keep it under observation for 1 more day and let you know.

Would like to thank BADCAPS FORUM and Mon2 for prompt responses and guidance.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Are you able to probe the pads @ J6700 connector ?

The J6700 connector also contains the signals of interest.

We ran a jumper wire from C6712 and the screen is giving issue.
When there is No Image, the Voltage still remains 1.8V.


Removing F6700 solves the Backlight issue but the Trackpad Haptic Starts giving problem.

Current Status of the Board -
Replaced F6700,L6700 and R5610.

I am in a total fix. Please help.

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

When the lid is closed, what is the voltage at C6712?

Is this an image or backlight issue? Can you see the graphics with a flashlight around the front face of the display when there is no display?

Are you able to monitor the lcd backlight voltage when the logic board is mounted in the case?

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

When the lid is closed, what is the voltage at C6712?

Is this an image or backlight issue? Can you see the graphics with a flashlight around the front face of the display when there is no display?

Are you able to monitor the lcd backlight voltage when the logic board is mounted in the case?

When the LID is closed, C6712 has 0 Volts.
Its an Image Issue. Cannot see anything with the flashlight.
The issue is very erratic, doesnt happen always - It happened 2 times now and then with LID open and No Image on Screen the voltage at C6712 was 1.8V.

The logic Board is mounted , tell me which components to check?

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

If you remove the track pad fuse, the display will always show an image?

What is the voltage at c6712 when the track pad fuse is removed?

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

If you remove the track pad fuse, the display will always show an image?

What is the voltage at c6712 when the track pad fuse is removed?

Removing the trackpad is necessary? I am pretty sure the trackpad isnt faulty - No Corrosion or Dirt there.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

If you remove the track pad fuse, the display will always show an image?

What is the voltage at c6712 when the track pad fuse is removed?

When we removed the tracpad fuse the Display will function as per normal. Even when the old fuse was damaged and the PPBUS_G3H_TPAD_FLT was getting no voltage the Image Issue was fine for 2-3 days.

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Do you still have the following from post #10?

2. Secondly when we re-assemble the device, it doesnt switch on automatically or by pressing the p[ower button, we have to first put it on charge and then press the power button to switch it on.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Do you still have the following from post #10?

Yes.
When you pull out the battery connector and put it back, You will have to first connect the charger wait for the battery charging sign to come , then press the Power Button for it to switch on.

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

That is not normal. You likely have a leaky mosfet.

Remove all power. Meter in resistance mode.

Check the resistance of the battery mosfet @ Q7065:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post the resistance values & the scale used on your meter for these measurements.

As a quick test - remove Q7065 off the logic board -> then see if the logic board will power up normally without this mosfet using only the external power adapter.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

That is not normal. You likely have a leaky mosfet.

Remove all power. Meter in resistance mode.

Check the resistance of the battery mosfet @ Q7065:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post the resistance values & the scale used on your meter for these measurements.

As a quick test - remove Q7065 off the logic board -> then see if the logic board will power up normally without this mosfet using only the external power adapter.

Any reference on how to probe a mosfet? The terms Source,Drain and Gate are alien to me.

Yes will remove the mosfet and see if its powering on or not.

[piernov]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

That is not normal.

Why?

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Why?

Does this logic board require a good battery to turn on? I would expect this logic board to turn on with only a good power adapter.

[piernov]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

That's not what they said.
However some machines since T2 have inconsistent behaviour regarding the presence of the battery (A2141 is known for that but I believe it's also a problem on some even newer ones), so best to try with a known good battery if all looks good but it doesn't actually turn on or doesn't go past low battery symbol.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

That is not normal. You likely have a leaky mosfet.

Remove all power. Meter in resistance mode.

Check the resistance of the battery mosfet @ Q7065:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post the resistance values & the scale used on your meter for these measurements.

As a quick test - remove Q7065 off the logic board -> then see if the logic board will power up normally without this mosfet using only the external power adapter.

Removed the Q7065 and same issue. It still does not boot up by pressing the power button for the first time.

Also now even if we remove the FUSE F6700, there is intermittent No Display Issue along with the Trackpad not vibrating.

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Check the removed mosfet with a resistance check:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Just to confirm there is no fault with this mosfet.

Then, place back this removed mosfet.

Does this battery charge if left on ?

As per @Piernov's comments, test with a known good battery.

[piernov]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Yes.
When you pull out the battery connector and put it back, You will have to first connect the charger wait for the battery charging sign to come , then press the Power Button for it to switch on.

This is normal. Looking at the battery connector circuit will explain why.

[Instafixx]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

Check the removed mosfet with a resistance check:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Just to confirm there is no fault with this mosfet.

Then, place back this removed mosfet.

Does this battery charge if left on ?

As per @Piernov's comments, test with a known good battery.

This battery charges when left on. There is no power or battery issue.

Do not have a known good battery.

What should i do?

[mon2]

Re: Macbook A1932 Intermittent Backlight Issue 820-01521

This battery charges when left on. There is no power or battery issue.

Do not have a known good battery.

What should i do?

Ok - so this is your known good battery if it the battery charges to the full potential -> can report the # of charges / stats of the battery pack -> can operate without the external adapter (after it is charged) and power the laptop for a normal duration of use.

If the battery depletes quickly, etc. then the pack is weak and should be replaced.