T28P Handset Noise Problems

[Yealink Support]

(03-04-2014 09:49 PM)braymond Wrote:  4101313044400001
4101313044400116
4100313044400168

Thanks,
Benoit

Hi Benoit,

We have sured that the three phones are broken.
Please ask your distributor for RMA or replace handsets.
Sorry again for the inconvenience.

[Yealink Support]

Hi all, If you encounter this kind of issue , please ask your distributor for help. They can debug and help you soon.

[anonymous1718628087441]

Dear Support,
we have same problem with T26.
At the moment we have installed more or less 900 pcs.
We observed a 10% of faulty handset.
The problem is a noise listened (as 50Hz buzzing),
but the issue come out after a short period of using (like 1 or 2 month) not immediately soon installed.
My opinion is the cause is the welding on the electret microphone.
I had same experience issue with telephone of other vendor .
Immediately Solution (workarround); give it a "shot" at the handset.
Definitely Solution : change the handset.
Repair the Handset: replace the welding or remove the "silicone" on the welding.

Sorry but I have not the serial number of the telephones affected.

Regards
Walter

[braymond]

Hey Walter,

What I did is to take the handset apart and untwist the wires that is close to the mic. It seems like it causes inductance like a coil and creates that buzzing noise. As soon as I replace the wires to not be twisted, noise goes away.

Benoit

[anonymous1718628087441]

Dear Benoit,
my idea is different. Sometimes give a "snap" at the handset, is enough and the noise disappears. I think the problem is the metallic microphone casing, or the contact between the welding and the common terminal connected to the casing

Bye
Walter

[belcom]

My analysis has been similar. It seems the silicon dab covering the electret microphone somehow breaks down, and takes on some capacitance. When you remove the silicon, it instantly resolves the buzzing sound completely. This could be why the buzzing sound disappears after the handset has been removed from the curl cord and left to sit for a few days. However, this does not always resolve the issue. The definitive method seems to be to remove the silicon entirely. The microphone seems to hold well in the casing even if the silicon is removed.

[mbello]

Ok, I have about 15 T46g on my company and experiencing this issue once in a while.

When buzzing sound develops on a handpiece the only solution up to now was to leave it unplugged for many days and even that was hit and miss.

Now after reading your experience I got two handpieces that I knew were buzzing, plugged them to my T46g and confirmed they were still buzzing. Then I opened the first handpiece and removed the silicon/wax completely and tested the handpiece... buzzing sound was gone! I did not need to untwist the cables.

However, my question was: is it gone for good or only for a few months and will develop again like has happened over and over with these phones?

To try to answer that I took the second bad handpiece, tested again to know it was buzzing and instead of completely removing the silicon/wax, I only removed enough so that my screwdriver could make contact with the metal case of the microphone. As soon as I did that, I tested the handpiece and the buzzing had stopped.

Therefore my hypothesis is that removing the silicon/wax fixes the problem because in the process of removing it you will end up touching the mic metal case with a metallic part and it will remove whatever charge was building up on it. So in that sense it is not a permanent fix. However, it may be possible that once exposed to the air the mic will never build up such charge again. Who knows? I guess only time will tell.

At least now we are getting close to knowing how to fix our handpieces.

Tip: when opening the handpiece, after taking the screw out pull the handpiece apart by making pressure where the RJ11 port is located. It is by far the easiest way to split it open.

[belcom]

Good to know about how to open the handset @mbello. Thanks! I was twisting it to expose the top lock tabs, but your method seems easier.
Regarding the silicon dab, my experience is once removed, the issue is resolved---and it makes absolutely no difference to the user or the call quality. To paraphrase a surgeon's reply 'when in doubt, cut it out'. It just works. We have handsets from 2009, and they started showing signs of failure here and there around 2014. There is about a 1% failure rate on 1K pcs. Thank God!

[dtgriscom]

In case this is useful, I just had the same thing happen to my headset. Sounds like 60Hz (in USA) buzz, in the handset only. Whacking it didn't help, unplugging and plugging the headset cord didn't help. Finally resolved to open it up to check the mic, and unplugged it, but couldn't get it open (even with the screw out). After five minutes, plugged it back in: problem gone.

So, if you have this problem, try unplugging your handset for a while and see if that alone fixes it.