AVS-1210
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Revision 06
TECHNICAL DESCRIPTION
See wiring diagram 804341.
The AVS-1210 comprises a single printed circuit board mounted in a 1 RU chassis.
Where local control switches are fitted, these are mounted on separate boards behind the front panel. A technical
discussion of these control boards and the data protocol employed may be found in the CPS-1050 / CPS-1052 /
CPS-1210 / CPS-1220 control panel manual.
AVS-1210 chassis wiring:
Chassis wiring for the AVS-1210 is shown on Dwg 804341.
The input fuse is located inside the IEC power connector socket and should be as follows:
240 Vac
250 mA slow blow.
110 Vac
500 mA slow blow.
A voltage selector switch on the rear of the unit allows for 110, 130, 220 or 240 Vac operation by selecting a
combination of primary windings on the power transformer.
Power on indication is via a neon indicator built into the power switch on the front panel. The brightness of this
neon indicator will therefore vary according to the mains input voltage.
The two secondary low voltage windings from the transformer are wired in a centre-tap configuration to provide
raw low voltage AC to the DC power supply located on the video PCB.
Video PCB:
(Refer to drawing 804338 sheets 1 & 2.)
Power supply
The power supply section consists of a bridge rectifier (D 1 - 4) and two 3 terminal regulators providing reg
and -10 Vdc supply lines.
Video circuit
The Video inputs are directed to one of three Gennum GX4314 4 x 1 multiplexing IC’s (U 1, U2 & U 3).
According to Gennum, “the GX4314 is a wideband video multiplexer characterised by excellent differential phase
and gain in the enabled state, very high off-isolation in the disabled state and fully buffered unilateral signal path.
Make-before-break switching assures virtually glitch-free switching.
For use in N x M routing matrices, the GX4314 features very high, nearly constant input impedance coupled with
high output impedance in the disabled state. This allows multiple devices to be paralleled at the inputs and outputs
without additional circuitry.”
For additional information see Gennum data sheet for this device.
The use of three multiplexers allows for a maximum of 12 inputs. The 11
th
and 12
th
inputs are tied together and
used as an expansion input for forming switchers greater than 10 x 1.
The output of the three multiplexers is buffered to two outputs by video amplifier U 4. RV 3 is included to provide
trim of DC offset at the output and RV 1 provides limited gain adjustment to ensure a 1:1 transfer characteristic for
the switcher overall.
Synch circuit
The switchers may be operated in either a local or remote sync mode in order to allow simultaneous switching of
different signals in multilevel applications.
This implies that the matrix will not switch until a sync pulse is received. When this is not provided externally, a
local sync needs to be provided.
A sample of the video output signal is taken to a video synch separator IC (U 5). The vertical synch output is then
further processed by monostables U 6a & U 6b to produce a suitably timed signal to synchronise switching to the
vertical interval. RV 2 is included to generate a latch pulse timed to fall approximately 10 lines into the field period
of the video signal.
The “localsync” signal is passed to the PLA via link LK 4, which allows a choice of internal or external sync to the
switcher logic. The chosen sync is echoed to “vertout” which is available on the PL 5 remote connector for slaving
other switchers. See
Configuration
section for details.
