System Installation Troubleshooting; If No Sound In The Theater; If One Audio Channel Is Missing; If Theater Audio Is Distorted - QSC DCM series User Manual

Digital cinema monitor & crossover system

Table of Contents

D. System Installation Troubleshooting

1) Monitor the PROC position to verify proper sound input to the DCM.

2) Check sound in AMP position.

3) If no sound, check that the amplifiers are on and the volume is up.

4) verify no Load Fault indication. If there is a fault indication, press and hold the Diagnostics

button and an LED will light above a channel indicator (L,LC,C,RC, R,SL,SR,SUB). The channel indi-

cated has a cable or speaker problem. Use standard audio troubleshooting techniques to isolate

which of these is at fault.

5) If there is no Load Fault indication, switch the Bypass switch to the Emergency position and

verify that proper center channel audio is present. We now know that the cables, amplifier, and

speaker for the center channel are okay. If you switch this back and still have no sound, check the

DCM configuration file using the DCM Commander software.

Connect with the DCM Commander software and upload the DCM configuration into your PC.

See if the Crossover | Mute Settings screen shows any channels muted.

If not, verify that the amplifier for that channel is on and the volume is up. Reseat the cable for

that channel and replace it with another if needed.

Verify that the DCM Input Clip LED is not flashing. If it is, the cinema processor output signal

needs to be turned down. If it isn't, see if any amplifier clipping lights are flashing. If they are,

then the either the output level of the DCM must be made lower or the amplifier sensitivity must

be changed. Refer to the amplifier manual which tells how to do this.

The DCM output level can be adjusted in the DCM Commander software. This is done in the

Crossover | DSP Settings | Gain. Remember that these gain settings compensate for driver

sensitivity differences, so all the high and low (or high,mid,low) gains should remain the same

number of dBs apart (compared to their factory speaker setting).

The circuitry which the signal passes through in the Bypass mode is extremely simple (resistors

and capacitors which do not require power). Therefore, if you set the Bypass switch to the

EMERGENCY position, and you do not get sound out of the center speaker, the problem is

either:

1) no input to the DCM, or

2) the center channel amplifier is off or the volume is down, or

3) there is a cable problem from either the DCM to the amplifier, or from the amplifier to the

Table of Contents

Troubleshooting