Sennheiser interference from window heat

[skyflyer737]

Hi

I have a Sennheiser HMEC 45-KA active noise cancelling headset which has an annoying problem. I'm an FO and therefore sit in the RHS of the 737-800 I fly. When I turn on the active noise cancelling I get (around 25% of the time) an irritating beeping and interference in my left ear.

I've tried adjusting the mic sensitivity but it doesn't appear to have worked. It gets worse as I turn my left ear towards the window so I'm guessing it's the window heat which is causing it. By touching any metallic part of the flightdeck with my hands it reduces the noise - e.g. touching the switches on the overhead panel.

By pressing the earpiece firmly I can get rid of it for 30 mins or so but it almost always comes back.

Does anyone have any suggestions?
Thanks a lot!
SkyFlyer737

[latetonite]

I have a Telex, works perfect in the 738..

[WallyWumpus]

Hi Skyflyer,

I joined pikey-air on the 738 this year and treated myself to a HMEC-25KA. I had the same problem that you describe from the get-go, and I called the UK service centre after a week. The (very helpful) staff said that this was a known problem and required a new microphone to be fitted. As the headset was brand new this was obviously a warranty fix, so I duly sent it off.

Annoyingly, it took 6 weeks to get it back, but I have not had any problems since it came home.

Details on the Sennheiser website.

Wally.

[FCS Explorer]

put the ear-piece with the cushion to your leg and slap the outer side (where the mike for the ambient pick up is) with your flat hand. about 3-4 times should do. usually solves the problem for the day.
some people also bang it to the side card clipboard. compared to that my method is relatively gentle.

[I Just Drive]

Pinch the mike with your thumb to totally block the mike and it resets. Been doing it for 8 years.

[skyflyer737]

Thanks a lot for your help guys - much appreciated. Will try the banging / resetting and if it fails send it back to Sennheiser.

Thanks again
SF737

[yrvld]

turn the window heat off and see what happens. :ok: