TL Audio VTC - Manual (Page 43)

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automation systems may retain the module fader path - please refer to the automation system installer
for details.
The Stat (status) switches are also provided for use with certain automation systems only. They are
momentary switches intended for identifying a signal path to the automation system computer.
The channel and MixB paths may be routed to the equaliser section by switches SW5 and SW6. The
channel path also has an overall EQ in/out switch on PC332, via signals CHAN EQ OUT (JP2-15)
and CHAN POST EQ (JP2-2). The channel and MixB paths are phase corrected by IC7A and IC7B,
where the balanced PFL signals are also generated, and then routed via the mute circuitry, IC12 and
IC3, to the faders. The post fade signals are buffered by IC7A and IC9A respectively, and taken via
the Pan controls to the balanced drivers and routing switches. The post fade signals are also routed
back up the module to the Aux sends on PC331.
The signal source selection for the Direct Output is made by the Buss switch, SW10, selecting either
the channel post fade signal or the group mix from the backplane (BUSS IN at CN5-20C). The
backplane tracking routes group 1 to module position 1 (i.e. channels 1,9,17, etc), and group 2 to
position 2, etc.
3.9. Module Fault Finding.
The input modules may be removed from the frame for ease of fault finding. Two extender cables are
provided with the console, and should be used to re-connect the module to the two backplanes. The
module can be easily probed with an oscilloscope if it is laid on its side on top of the adjacent
modules, which should be protected with a sheet of cardboard or other insulating material.
4. Master Section.
4.1. Mechanical Construction.
The console master section is constructed in a similar manner to the input bays. A steel cradle
provides mechanical support for two backplanes, PC355 and PC336, whilst the regulator and valve
PCBs are located in the rear section. Two master module assemblies plug into the backplanes via
IDC cables.
When fault finding on the Master section, either or both modules may be propped open with the IDC
cables still connected.
CAUTION: Switch off the power before attempting to open the Master section. Care must be taken
not to damage the IDC cables or the talkback microphone screened cable as the modules are
removed.
Under normal operating conditions, only the +/-15V supplies are present on the Master modules and
backplanes. Note that the same regulator module, PC357, is used for the input bays and Master
section, but the 48V output is not used in the Master section.
The Valve PCB, however, is different to that used in the input bays. The Master Valve PCB is
PC345, which contains similar circuitry to PC334, but certain signal phases are different. The signal
path names are identified along the rear edge of PC345, in line with their valves and trimmers. If the
valve boards are fitted to the wrong bays, signal continuity will be preserved, but with phase reversal