Philips SM40 Instructions For Use Manual page 102

5. SM40 MODULES
5
X101 :
X102 :
5-42
Jumper normally set in position 2 - 3. For service purposes the jumper can
be set in position 2 - 1, the battery will be disconnected (contents of
message(s) therefore will be lost.
When the jumper is placed in position 1 - 2, the switch of the connected
microphone can be used to start/stop a recording.
1 2 3
see below:
3 2 1