Bypass Operation - Dolby Laboratories CP650 User Manual

CP650 User's Manual
2.3

Bypass Operation

The CP650 has an independent power supply for emergency operation. If the main
power supply or processor circuitry fails, the unit will automatically switch to bypass
operation, allowing the show to continue with limited sound processing functions.
Bypass operation is indicated by the front-panel power button glowing red.
In the case of other problems, such as distortion or the loss of a channel, the bypass
mode can be selected manually by pressing the power button.
There are other components in the theatre sound system that could also fail. Be sure
to refer to Chapter 4, Troubleshooting, any time there is a problem.
The following occurs when the CP650 is operating in the bypass mode:
•
The power button glows red and the display screen is off.
•
Only the front-panel main fader operates; no other remote fader works.
•
All other front-panel buttons do not work.
•
The optical preamp circuit of the selected projector remains operational and is
fed to the CP650 left, center, and right channel outputs.
•
Even when a stereo print is playing, a mono signal is fed to all screen
speakers. Thus, you can switch to the bypass mode to keep the show going if
one of the power amplifiers fails.
•
All Dolby processors, speaker equalizers, and subwoofer circuits are switched
out of the signal path.
Be sure to follow the troubleshooting procedures and, if necessary, call your service
engineer as soon as possible.
Note: The CP650 will not operate, even in the bypass mode, if there is a fault in any of the following areas:
•
The AC mains power to the CP650.
•
Bypass power supply fuse or bypass power supply circuit.
•
The optical preamplifier circuitry or bypass circuitry on the Cat. No. 772 board.
It is strongly recommended that a spare Cat. No. 772 board be kept on hand for substitution in emergencies.
If the front-panel bypass power supply failure indicator (located directly above the
main fader knob) is on, the CP650 will not operate in bypass mode.
2-11
Operating Instructions