GSM-noise "buzz" issue

Andy Green andy at
Tue Sep 16 15:23:47 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:

| The sound I had  after completely removing JK4401 was the identical GSM
| buzz that I had before removing the connector. I would say that it was
| possibly even worse than with the connector attached.

| I didn't have the connector with me so to try and rectify my partial
| rework I added a short between 3 and 5 to match the closed connection in
| the headset plug. That fixed it. There is a very minor hiss that remains
| but the phone is usable for talking now.

I guess what you're saying is actually compatible with what we think we
know.  When 3 and 5 are open, it selects the headset mic path in
software since it believes that the jack is inserted.  We only thought
that the internal mic path is helped by headphone jack removal.  So it
would require 3-5 short to select the internal mic again as you have done.

| I probed the connector a bit and the strip of metal up the side above
| pin 4 is connected to pin 4. Couldn't pin 4 be filed off. Then lean (
| and solder ) the bead from the pad for pin 4 against the metal strip up
| the side of the connector ?

It doesn't sound insane, but I am kind of hoping our understanding of
the path this noise takes to actually make the buzz at WM8753 can still
increase to the point it might suggest another easier place to intercede.

BTW props to you sir for jumping in there and start experimenting with
jack removal, that is not so trivial to think about for a customer.

- -Andy

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