Service manual

STP 11-25R13-SM-TG
3 - 50
REPAIR AN AUDIO CONSOLE
113-575-0060
Conditions: In a tactical or garrison environment, given a DA Form 2407 requirement for an audio
console (installed in a system with wiring, input sources, and output destinations), audio amplifier,
speakers, dual-trace oscilloscope with 10X test probes, multimeter with test leads, ATSG, extender cards,
card pullers, electronic equipment tool kit, soldering tool kit (light to medium duty), bench stock, DA Pam
738-750, and manufacturers' manuals.
Standards: The standards are met when the audio console is repaired and no other problems exist.
Performance Steps
1. Review the DA Form 2407.
2. Sectionalize the trouble to a defective stage.
a. Visually inspect for physical damage, missing controls, broken switches, broken wires or
connections, and other discrepancies.
b. Operations check the console to verify that the deficiency or symptom exists and to what
extent.
NOTE: Always refer to the operations guide as a first step in resolving problems with the console to
ensure that the difficulty is not an installation or operational error.
(1) Turn ON console power (if not already ON).
(2) On stereo line input (SLI) modules, depress the CUE pushbutton and listen to the signal
on the console-mounted loudspeaker or headphones if broadcasting a signal from another
module.
(3) Select the suspect source module. If the console is bypassed or not on-air, activate the
module ON pushbutton and slide the level control fader up to monitor the signal.
(4) Depress the appropriate input, A or B, on the INPUT SELECT pushbuttons. Verify that the
input is +4 dB equaling 0 VU.
NOTE: The module automatically turns OFF with both input pushbuttons depressed or released.
(5) Depress either or both (PGM and AUD) OUTPUT ASSIGN pushbuttons.
(6) On SLI modules, set the Mode Select switch to the desired stereo output.
( a) STEREO.
( b) SUMMED LEFT AND RIGHT MONO.
( c) RIGHT SOURCE ONLY.
( d) LEFT SOURCE ONLY.
(7) Verify both left and right channels on the VU meters and speakers.
(8) Verify the correct setup of the Control Room Monitor (CRM) module.
( a) Set the CUE level control to a comfortable listening level.
( b) Depress the Monitor Select switch for the source for monitoring on the control room
speakers and the headphones.
( c) Ensure the speaker ON-OFF pushbutton is not manually muting the control room
speakers. When muted, the adjacent LED illuminates; also the speakers mute and
the LED illuminates when a Microphone Input Select (MIS) module is in operation.
( d) Set the control room level for the CRM speakers.
( e) Set the DIM control for a level of preference. This control reduces the level of the
monitor signal when the CUE function is in use.
( f) Set the headphone EQ, Source Select, and Level controls to desired effect.
3. Localize the trouble to a specific circuit.
CAUTION: To prevent damage, turn OFF console power before removing or inserting modules or
accessories.
a. Signal trace by following the functional block diagram (signal flow) located in the manufacturer's
manual.