Studio Technologies 220 2013 - Manual (Page 36)

Issue 5, February 2013 Model 220 User Guide
Page 36 Studio Technologies, Inc.
Additional functions can be accessed
using these 3-position headers:
P9: Auxiliary Relay Contact B,
pin 1 normally closed, pin 2 common,
pin 3 normally open.
P10: Auxiliary Relay Contact A,
pin 1 normally closed, pin 2 common,
pin 3 normally open.
P16: Internal Power Supply Rails, pin 1
common, pin 2 +12 Vdc, pin 3 -12 Vdc.
P17: Remote Switch Connections,
pin 1 common, pin 2 talkback 1 button,
pin 3 talkback 2 button.
P18: Remote Switch Connections,
pin 1 common, pin 2 main out button,
pin 3 auxiliary (currently not supported
in software).
P20: Remote Data Interface, pin 1
common, pin 2 data +, pin 3 data -.
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 220 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 incan-
descent type but we find that the more
modern leaded T1 LEDs work very well.
The Model 220’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 220. Power up the Model 220
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.
Remote Control Connections
Provision has been made on the Model
220’s printed circuit board assembly to
allow external switches or contact closures
to control the main and talkback output
functions. Two 3-position headers, labeled
P17 and P18, provide access to the cir-
cuitry associated with the functions.