QSC CM16a Hardware Manual page 26

Section 3:
Operation- Bypass Switch Usage (continued)
NOTE! Before depressing the BYPASS switch, the gain (volume) settings on all amplifiers
connected to the CM16a should be reduced to a safe level. This is advisable because the
CM16a's "Level Control" will be reset to 0 dB. (or NO attenuation) with the BYPASS. It is
possible that the amplifiers could be at maximum output level if the amplifier gain controls are
not turned down.
Location of BYPASS switch: The front panel has a small access hole on the right side about 12mm (1/2 inch) to the right from the PORT
H LED. It is NOT LABELED to help prevent accidental use. This is the BYPASS mode switch. To return to normal operation, simply reestablish
computer communications via the network or RS-232 and change the appropriate settings (or recall a previously saved Preset).
The way to put the CM16a into this first BYPASS mode ("virtual-wire
mode") is:
1- Turn the CM16a on and wait 5 to 10 seconds for the start-up LED
sequence to finish.
2- Depress the BYPASS switch (use a paperclip or similar item) and keep
it depressed for at least 5 seconds.
3- The two steps above must be completed within 60 seconds from
power-up. If you miss the timing, just power-down and power-up again and
repeat steps 1 & 2.
The second mode ("safe" mode)is used if the CM16a becomes inoperable (or behaves in completely unexpected ways) after
uploading a new application file (TFTP file transfer).
If the CM16a behaves in unexpected ways or is not responding to any communications after a new application file is uploaded to it, then
it is likely that the new application file was corrupted during or after the data transfer. If sent a corrupted application file, the CM16a will
not accept this file. The LED's might even act in unexpected ways. If this occurs, there is a "backup" file in the CM16a that will enable you
to communicate with it.
The way to put the CM16a into this second BYPASS mode ("safe mode") is:
1- Turn off the power to the CM16a using the front panel power switch.
2- Depress the BYPASS switch (use a paperclip or similar item) and keep it depressed while turning the power on again.
3- The CM16a is now in "safe mode".
You will now be able to re-establish communications with the CM16a using the RS-232 Input/Output port or the Telnet program in Windows
NT. The following section describes the RS-232 and Telnet features. Once communications has been re-established, the file transfer can
be tried again or the old application file used until the source of the data transfer problem can be found.
26
FRONT PANEL- BYPASS SWITCH LOCATION