TL Audio VTC - Manual (Page 40)

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3. Input Bays.
3.1. Mechanical Construction.
The input modules are carried in a steel cradle which is mounted between the console bulkheads. The
cradle provides mounting screw points for the modules, plus two rigid PCB backplanes into which
the input modules are plugged. All connections to the input modules are made via a two part
DIN41612 connector on each of the backplanes. To remove a module, the large black countersunk
screws at the top and bottom of the module should be taken out, after which the module can be
simply pulled clear of the console.
Note that consoles fitted with third party Automation Systems may be installed with additional flying
leads to the module and/or faders, and care must be taken not to damage these leads as the module is
withdrawn.
Both backplanes are passive, i.e. they contain connections only, with no active circuitry (refer to
CD1356 and CD1337). The upper backplane, PC356, (nearest the VU meters) carries the power
distribution to the input modules, as well as the inputs and outputs for the module, and balanced Aux
busses. The power connection may be checked by removing the middle two modules, and measuring
the voltage rails as marked on the rear of CN30.
The non-patchbay standard console has a separate 16 way IDC cable for each module, carrying the
Line Input, Insertion Send + Return, Monitor (Tape) Input and Direct Output to the small PCB
(PC335) onto which are mounted the rear panel jack sockets. These IDC cables are secured in place
in the console frame, and terminated onto PC356. Consoles with internal or external patchbays have
longer IDC cables, taking the above signals from PC356 either directly to the patchbay PCBs or to
multiway connectors.
Irrespective of any patchbay, the microphone input for each module is via a rear panel mounted XLR
connector with an individual screened cable terminated directly onto PC356, close to the module
connector. This ensures minimal PCB track length for the mic signal, to achieve good noise
immunity.
The lower backplane, PC337, carries the balanced buss signals along with PFL and Solo signals.
3.2. Adding Modules to Sub-fitted Consoles.
Each Input Bay is normally fitted with eight input modules, although some consoles may be sub-
fitted with individual module blanks or full bay blank panels. When retrofitting modules to consoles
initially supplied part fitted, the new modules can be simply plugged into the backplanes. The valves
for the new channels will also need to be fitted to PC334, and the console calibration procedure
followed. Note that modules should be dedicated to particular positions in the console. If they are
moved to another position, the relevant valve stages should be recalibrated, and the engraved mute
buttons exchanged.
CAUTION: THE CONSOLE POWER SUPPLY MUST BE SWITCHED OFF BEFORE ANY
MODULES OR VALVES ARE PLUGGED IN OR OUT .
3.3. Input Modules.
The channel modules consist of three PCBs mounted onto a reversed U-section sub-front plus front
panel: