Pushbutton Backlighting

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).

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

Model 233 User Guide	Issue 1, September 2007
Studio Technologies, Inc.	Page 41