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Model 233 User Guide Issue 1, September 2007
Studio Technologies, Inc. Page 41
of the enclosure and two on the back
panel, must be removed. A 5/64-inch hex
driver is required. The cover can then
be carefully separated from the chassis,
remaining attached by means of a flexible
cable assembly. This “flex-cable” assem-
bly links the main printed circuit board
assembly with the board assembly that
contains the pushbuttons and LED indi-
cators. Ensure that the flex cable is not
damaged while the Model 233 is being
customized. For easier access, the push-
button/LED board assembly can also be
easily removed.
The 3-position headers on the Model
233’s main circuit board assembly are
located close to their related input or out-
put connectors. The following list provides
the printed circuit board reference num-
bers and associated functions.
P4: 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 P13 is used
by the back-panel 24 Vdc jack assembly
and is electrically in parallel with P4.
P5: Headphone output, pin 1 common,
pin 2 tip (left), pin 3 ring (right).
P6: Microphone input, pin 1 common,
pin 2 high, pin 3 low. Follows back-panel
3-pin female XLR pin assignment.
P7: Main output, pin 1 common, pin 2
high, pin 3 low. Careful! Back-panel 3-pin
male XLR has pin 1 floating, pin 2 high,
pin 3 low.
P8: Line-level talkback output 1, pin 1
common, pin 2 high, pin 3 low. Careful!
Back-panel 3-pin male XLR has pin 1
floating, pin 2 high, pin 3 low.
P9: Line-level talkback output 2, pin 1
common, pin 2 high, pin 3 low. Careful!
Back-panel 3-pin male XLR has pin 1
floating, pin 2 high, pin 3 low.
P10: Line input 1, pin 1 common, pin 2
high, pin 3 low.
P11: Line input 2, pin 1 common, pin 2
high, pin 3 low.
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.
P14: Pushbutton backlighting, pin 1
common, pin 2 button lamps, pin 3 current
limited 24 volts from external 24 volt DC
input.
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 connections,
pin 1 common, pin 2 talkback button 1,
pin 3 talkback button 2.
P19: Remote main output/tally output
connections, pin 1 common, pin 2 main
output button, pin 3 tally output (+3.5 volt
DC, 12 milliampere maximum).
Pushbutton Backlighting
For special applications, provision as been
made to allow illumination (“backlighting”)
of the three pushbutton switches. This
may prove useful for applications where
adequate room lighting is not available.
It can also serve in custom Model 233