MCE-325 Programmable User Station
Installation 25
Bosch Security Systems, Inc.
Technical Manual
F.01U.193.228
Rev. 13
Program Assistant – IFB Option (J4, J5, J16-J18)
Jumper J4 assigns PROGRAM A to 2-wire CH 3 or 4-wire CH B with interrupt during talk (IFB A). Jumper J5 assigns
PROGRAM B to CH 4 with interrupt during talk (IFB B). (PROGRAM B is not used in 4-wire mode.)
Jumpers J16, J17, and J18 assign the mono mix of both program inputs to the left headphone, right headphone, and speaker
respectively. Program volume to the headphones and speaker is controlled by the PGM VOL control on the front panel.
See Table 2 on page 22 for jumper settings. See Figure 13 on page 23 for locations of jumpers.
Balanced/Unbalanced Dynamic Microphone Selection (J24)
The MCE-325 may be used with headsets having either a balanced or unbalanced dynamic microphone. The MCE-325 is pre-
programmed for use with an unbalanced microphone by shorting J24 pins 1 and 2. For balanced microphones, remove the
shorting jumper and reinstall it to short pins 2 and 3.
Headphone Sidetone Trimmer Adjustment (R37)
The headphone sidetone trimmer (R37) adjusts the loudness of your own voice heard in your headset when the microphone is
on and the speaker is off. (It does not affect the actual level heard on the intercom lines.) This trimmer is preset so your voice
level in the headphones is approximately ¾ of the intercom line level. To prevent feedback, this signal is automatically turned
off when the external speaker is turned on with the SPKR ON switch.
Speaker DIM Adjustment (R157)
When an external speaker is used, switching the microphone on causes the speaker level to attenuate. The level of attenuation
may be adjusted with the speaker dim trimmer (R157). The minimum attenuation of 6dB is preset at the factory (R157 fully
clockwise). The range of adjustment is -6dB to -40dB.
Mechanical Installation
Dimensional requirements for the various mounting configurations can be see in Figure 14. Also allow an additional 4.0
inches (102mm) of rear panel clearance for connectors.
If the headset connector is remotely located (See “External Headset” on page 30), allow space between the cable and
interfering sources, such as TV monitors, power supplies, and equipment with internal power supplies. The MCE-325 has no
special ventilation space requirements.
