MacBook A1708 820-00840-a speaker making strange noises

[dbuergi]

Hi all,

i fixed a A1708 which was not working. Not its booting but the left speaker is making buzzing and sizzling noises. I added a short video to show it.
https://www.dropbox.com/scl/fi/ju6v7...=lewlrdkh&dl=0

I already reflowed the audio codec chips but that didn't help. Any ideas what to do?

[mon2]

Sounds like your fan is rubbing. Disconnect the fan connector and test again without the right side fan running.

[dbuergi]

Sounds like your fan is rubbing. Disconnect the fan connector and test again without the right side fan running.

Hello mon2,

will try it later but the sound comes right away when i Start the MacBook and doesn't come with speaker FLEX disconnected.

[dbuergi]

Little update here. I found a short a U6460 removed the chip and it was gone. After replacing it with a donor i also found a short at U6440. Same game and now all shorts are gone and 1,8v are present but i still get no sound but the noises stopped. I also tried PRAM reset without any success.
So maybe any other ideas? The fan is not the cause of any problem.

[mon2]

U6440 is a dainty WLCSP package. Soldering ok? Remove all power. Measure the ferrite bead L6440 in DIODE mode. Red meter probe to ground. Black meter probe on L6440.

Repeat for L6441. Suggest to disconnect the speaker so that we get a measurement of the amplifier chip. You should have a voltage reading in diode mode. If OL, then the amplifier output is disconnected.

[dbuergi]

U6440 is a dainty WLCSP package. Soldering ok? Remove all power. Measure the ferrite bead L6440 in DIODE mode. Red meter probe to ground. Black meter probe on L6440.

Repeat for L6441. Suggest to disconnect the speaker so that we get a measurement of the amplifier chip. You should have a voltage reading in diode mode. If OL, then the amplifier output is disconnected.

L6440 and L6441 both show 0,6V.
L6460 and L6461 also 0,6V.
I reballed U6440 and U6460 and soldering back went without any problems.

[mon2]

At this point, do you have any sounds working from either speaker?

Review, U6460, U6440, U6420, U6400 which are the audio amps.

Also of importance is the audio codec @ U6200 which converts the audio streams for the logic board.

Do check if the s/w is able to see this audio device in the hardware. BTW - are you able to hear any sounds with a headphone? BLE headphones? Assuming this to be ok.