EQUIPMENT MANUAL 251-16-1
251/251-16-1
Page 2
monitor outputs cannot be deselected or muted independently of the normal input switching
circuits.
The operating modes of the Model 251 are established when either a ground (low) signal or a 12
to 32 VDC (high) signal is applied as listed below to the connector pin listed:
Control
Pin No.
Signal Identification Function
P50-16 Low ADF 1 Switch Connects ADF 1 input audio to left
and right speaker and monitor outputs.
P50-15 Low ADF 2 Switch Connects ADF 2 input audio to left
and right speaker and monitor outputs.
P50-14 Low PSC Switch Connects Pilot Select Comm (PSC) input
audio to left and right speaker and
monitor outputs.
P50-13 Low TV Switch Connects TV input audio to left and right
speaker and monitor outputs.
P50-5 Low Stereo Switch Connects stereo left and stereo right
input audio to left and right speaker
and monitor outputs, respectively.
P50-24 Low PA Key Connects PA MIC input audio to PA
sidetone, left and right speaker,
and monitor outputs. Opens ADF, PSC,
TV, and stereo input audio circuits.
P50-25 Low Briefer Switch Connects briefer input audio to PA sidetone,
left and right speaker, and monitor outputs.
Opens ADF, PSC, TV, and stereo
input audio circuits.
P50-31* High No Smoking Chime tone to left and right speaker
and monitor outputs. Opens ADF, TV,
PSC, and stereo inputs.
P50-32* High Seat Belt Chime tone to left and right speaker
and monitor outputs. Opens ADF, TV,
PSC, and stereo inputs.
P50-33 Low Cabin Call Ringer tone to left and right speaker
and monitor outputs.
P50-34 Low Hook Switch Disables ringer tone.
P60-8 Low Speaker Enable Enables left and right speaker outputs.
P60-3 Low Speaker Mute Mutes (lowers volume -6 dB) left and right
speaker outputs.
*An application or
removal of a High signal at pins P50-31 and P50-32 will provide a chime tone at
left and right speaker outputs regardless of speaker enable status.
NOTE: P50-XX is a pin on the 37-pin connector, P50
P40-XX is a pin on the 25-pin connector, P40
P60-XX is a pin on the 9-pin connector, P60
All internal screwdriver potentiometer adjustments of the Model 251 are set to factory standards.
If it is necessary to change a setting, refer to Section 4.0 of this manual.
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General