Sennheiser RS120 ac adapter died

SOURCE: RS120 Can still hear TV when headphones are on

Ok.. first.. the simple thing is to go into your television menu and turn the television speaker OFF.
Then exit the menu and turn the volume up.. try your headphones now.

Next.. check the back of the TV for a FIXED AUDIO OUT.. plut your headphones into these outputs.. if you have these.. you can simply turn the set down.. and use the volume control on the headphones.

SOURCE: Sennheiser RS120 with noise...

Couple of things could be going on..

Try the obvious first

1. Select a different channel on the base unit: Located on the front, under the logo is a small switch. Note the position and try the other two settings
2. Make sure your base unit is not next to other items that may interfere with it.. cordless phones and wireless network routers etc.. microwaves or other RF sources .. fluorescent lamps.. etc

Lastly.. just about all wireless headphones have some noise or background hiss.. but it should be minor.. if the rechargeable batteries are not taking a full charge or cannot retain the charge properly.. the reception will also weaken.. and that noise will increase.. and the reception distance will decrease.

You can buy a new set of rechargeable batteries .. just make sure they are exactly like those in your headphones..

If I remember right.. they are Nickel Metal Hydride… (NiMH).. Radio Shack will have them.. or a store like Batteries Plus.. If you replace them.. go for a slightly beefier battery.. a higher mA-h.. may take a bit longer to charge initially.. (If you try this.. remember.. they will need to charge overnight before use) but will “play” longer in use.

It has been noted that many of these headphones shipped with inferior batteries.. that problems seems to have been addressed by the mfg.

Good Luck!