Changed batteries in the unit and the bell does not chime

Did you read the manual?

You need to pair the bell push and the chime unit with the same DIP switch settings. They do this in case you and your neighbours have the same unit. Someone press the doorbell and you all come to your doors. :>D

WIRELESS MECHANICAL BATTERY OPERATED CHIME

Trine Access Technology http://www.trineonline.com > 235_instructions PDF This device (WB-94A-TX or WB-97-TX/TR-6505-RX) complies with Part 15 of the FCC Rules and RSS-210 of Industry Canada. Operation is subject to the following ...
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What do you want to know ?
The door bell button has 1 12V alkaline battery type A23
not sure on the door bell unit on what battery it uses might be the same type ?
Both units have factory set toggle switches that you should not need to change - however the 1st 7 toggle switches control the code and must match on the door bell button and on the doorbell unit.
The eighth toggle switch controls the chime used so on or off on door bell unit or off or on on door bell button. there are three choice of chime..

Do not install the door chime on metal or near metal like wall studs with metal in them.
Make sure batteries in both units make contact with the terminals may be plastic insulator in the units - like packing / shipping insulator to save the battery life.

here is a web site with the units manual
http://homeappliance.manualsonline.com/manuals/mfg/heath_zenith/sl6166.html?p=1

siemens bell push W725TC Google Search

SIEMENS WIRELESS DOOR BELL JSJS 203

Siemens door chime jsjs-210
Without doubt the worst piece of design I've ever encountered.
The battery housing on the chimer is so large that on closing the lid with the batteries fitted they pop out, nothing holds them in place other than the contact elements - the case snaps shut with quite a jolt and the batteries just pop out...had to use a padded envelope cut to size to keep them in place.
Also the button unit is dreadful - the button isn't actually a button - it's a light, pushing the button just flexes the circuit board and activates a small push sensor on the reverse of the circuit board!?! WHY? A button that isn't a button? The sensor is also too short to touch the rear of the casing and thereby close the circuit - had to pad this out with 2 bits of cardboard...too much it will ring all the time, too little it won't connect.
Please do not buy this product - if you have return it, it is dreadful - and from Siemens it's not even funny.
Apologies for not answering the question directly - I was also searching for a manual for this, to maybe figure out why this device is so badly constructed.

With Siemens door chimes, there are often no dip switches. Instead you need to take the batteries out of both the receiver and the switch, wait for a few minutes, replace them and then try again. The set should "learn" the new frequency of the doorbell automatically.

You may need to change the frequency of the chime. In this model, you need to remove the batteries from the receiver unit and wait for a while. Then replace the batteries. The doorbell unit should automatically set itself to a different frequency once you press the button, which will(hopefully) solve the problem.

It seems impossible to find the instruction manual for the doorbell. But see http://oddsnsods.net/blog/?p=68 who had a similar problem with a different Siemens model, which works on the same principles. (I can't seem to be able to remove the battery from the door bell unit on the jsjs204, but it reset itself after changing the batteries in the receiver).

Hi

To fix the issue you need to remove the batterys from both the bell push and the bell unit for 10 mins, then replace the batterys and then push the bell push so it can switch channels and be different from the house down the road

Sandra, the contacts in bell push may need cleaning, as well as some minor readjustment of the contacts. Insects love to get into the bell push and can clogged it up. If you find that this doesn't solve the problem, Contact the Zenith Company 800-858-8501 to purchase a replacement.

From User Guide: Interference from a similar unit operating nearby: a) simply remove the batteries from the push button and door chime units and rest for 10 seconds, this will erase memory b) Insert the batteries into the push button and door chime units, the door chime unit will give 2-beeps to indicate that it is ready for the new registration code. Press the Push Button once, it will generate a new operation code randomly and send a wireless ignal to the door chime unit and it will sound to indicate that new operation code is registered and memorised.
(Note with this unit SX85R the door chime is mains powered, not battery powered, but above instructions are the same)