Studio Technologies M233-01151 - Manual (Page 41)

Model 233 User Guide Issue 5, November 2014
Studio Technologies, Inc. Page 41
P12: Intercom Interface, pin 1 common,
pin 2 DC with channel 1 audio,
pin 3 channel 2 audio. Follows back-panel
3-pin female XLR pin assignment.
P13: External 24 Volt DC Input, pin 1
common, pin 2 +24 volts, pin 3 not used.
Back-panel 2.1 x 5.5 mm jack has +24
volts on center pin. Header P4 is used
by the back-panel 24 Vdc jack assembly
and is electrically in parallel with P13.
P14: Remote Data Interface, pin 1
common, pin 2 Data +, pin 3 Data –.
P15: Auxiliary Relay Contact B, pin 1
normally closed, pin 2 common,
pin 3 normally open.
P16: Auxiliary Relay Contact A, pin 1
normally closed, pin 2 common,
pin 3 normally open.
P17: Internal Power Supply Rails, pin 1
common, pin 2 + 12 Vdc, pin 3 –12 Vdc.
P18: Remote Talkback Switch Inputs,
pin 1 common, pin 2 talkback button 1,
pin 3 talkback button 2.
P19: Remote Main Switch Input/Tally
Output, pin 1 common, pin 2 main output
button, pin 3 tally output (+3.5 volt DC,
12 milliampere maximum).
P21: Internal Power Supply Rails, pin 1
common, pin 2 + 12 Vdc, pin 3 –12 Vdc.
Pushbutton Backlighting
For special applications, provision has
been made to allow LED illumination
(“backlighting”) of the three pushbutton
switches. This may prove useful for appli-
cations where adequate room lighting
is not available. It can also serve in custom
Model 233 configurations. It’s important to
note that the button lighting is not intend-
ed to serve tally applications. It is strictly
intended to provide a moderate amount
of illumination of the button’s clear lens
and associated labeling.
From the factory, LED lamps are not
installed in the pushbutton housings. The
socket in each housing was designed for
inserting a pluggable T-1 bi-pin incandes-
cent type but we find that the more mod-
ern leaded T1 LEDs work very well. The
Model 233’s 5 volt DC power supply is
connected to the socket in each push-
button housing by way of 2.2 k (2200
ohm) resistors. With this implementation,
along with the recommended LED, only
1 milliampere per LED is consumed.
It’s intended that high-efficiency white
LEDs be installed. They use very little DC
current and have essentially infinite life.
The recommended LED is the Kingbright
WP7104QWC/D which as of the time of
this writing is available from sources
such as Digi-Key (www.digikey.com) and
Mouser Electronics (www. mouser.com).
The mating socket in each pushbutton as-
sembly is accessed by removing the but-
ton’s lens caps, graphic label, and back
frosted lens. Once this is done installing
the LED should be very simple, requiring
only lead trimming and careful insertion.
Begin by removing the top clear lens, la-
bel, and frosted under-lens in each push-
button. Trim the LED leads to 0.25 inches
in length and insert into the sockets with
the cathode end located nearest the front
of the Model 233. Power up the Model 233
and observe if the LEDs light. The LEDs
are polarity sensitive and if one or more of
them do not light, remove the offending
LED(s), rotate them 180 degrees, and then
re-insert.