Sennheiser hdr 120 headphones no longer hold a charge. where are the batteries in the headset?

Sennheiser Wireless Headphone HDR 120 Instruction Manual
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Can you remove the rechargible batteries ? To try and reset them ? Or maybe replace them ? It sounds like the batteries have gone bad and not charging

The headphones will automatically charge wirelessly when placed in the cradle that should have come with the package. To make sure the headphones are placed correctly, a red light should illuminate letting you know they are being charged and are properly placed.

This would seem to be more a function of the device to which you connect the headphones than the headphones themselves. Can you flesh out the details? There may be a setting you're unaware of.

The batteries are at end-of-life OR your charger has failed.

Forst replace the batteries... they are MOST likely bad. Charge the new ones before using.

I had complete silence on an HDR 130 headset (no beeps, nothing), but I solved this problem using a solution posted on another thread. Unplug the base, take out the batteries and wait 30 seconds. Reconnect it all and listen. Mine started working immediately!

A replacement battery can be purchased from Sennheiser for $20.00.
Battery Part Number: BA 151
Sennheiser Link:
http://www.sennheiserusa.com/newsite/productdetail.asp?transid=004146

A replacement battery can be purchased from Sennheiser for $20.00.

Battery is: BA 151

Sennheiser Link:
http://www.sennheiserusa.com/newsite/productdetail.asp?transid=004146

Did you try to remove the batteries and at the same time unplug the power of the base for 30 sec ?

These systems have some signal detection, so needs an input to fire it all up. That is the same for the greenlight, when initially switched on for my HDR 120.