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MODEL 161 INSTRUCTION MANUAL
Contents
Specifications .............................................................................. Page 2
General description ..................................................................... Page 3
Installation................................................................................... Page 3
Circuit description, plug- in circuit module 503135 ................... Page 4
Circuit description, LED control panel 503138 .......................... Page 6
Circuit description, incandescent control panel 803139 ............. Page 6
Parts list, 503135......................................................................... Page 8
Parts list, 503138......................................................................... Page 9
Parts list, 503139......................................................................... Page 9
Schematic diagram, 503135 (3 pages) ...................................... Page 10
Schematic diagram, 503138 ...................................................... Page 13
Schematic diagram, 803139 ...................................................... Page 14
Component locations, 503135................................................... Page 15
Warranty statement............................................................... Rear cover
Warranty registration card....................................................... Attached
Note: The serial control option, if ordered, is covered by a separate instruction manual
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MODEL 161 INSTRUCTION MANUAL
Specifications
Video input characteristics
Nominal video level........................................... 1V p-p
Maximum video level..................................... 1.5V p-p
Impedance............................................................. 75 Ω
Return loss .......................................... 40 dB @ 5 MHz
Superimposed DC.............................................. +/- 5 V
Connector type...................................................... BNC
Video output characteristics
Nominal video level........................................... 1V p-p
Maximum video level..................................... 1.5V p-p
Impedance............................................................. 75 Ω
Return loss .......................................... 35 dB @ 5 MHz
DC on signal .................................................+/- 50 mV
Connector type...................................................... BNC
Video system performance
Nominal gain ....................................................... Unity
Gain adjustment range ...................................... +/- 2dB
Frequency response .......................+/- 0.1dB to 5 MHz
............................................+0 -1 dB 5MHz to 20 MHz
..........................................+0 -3 dB 20MHz to 40 MHz
Diff phase .............. 0.1 deg @ 3.58 MHz or 4.43 MHz
Diff gain....................0.1 % @ 3.58 MHz or 4.43 MHz
Crosstalk .........................60 dB @ 5 MHz (all hostile)
...........................40 dB @ 40 MHz (bracketed hostiles)
S/N .......................................................80 dB to 5 MHz
System delay......................................................... 20 ns
Input timing variation ....................................... +/- 1 ns
Switching point.................. first line after vertical sync
Vertical rate ..............................................25 to 200 Hz
Audio input characteristics
Nominal input level ..........................+8 dBm @ 600 Ω
Maximum input level......................+18 dBm @ 600 Ω
Source impedance............................................... 600 Ω
Input impedance .................................................30 KΩ
Common mode rejection ......................40 dB @ 60 Hz
Connector type........................................Terminal strip
Audio output characteristics
Nominal output level ........................+8 dBm @ 600 Ω
Maximum output level....................+18 dBm @ 600 Ω
Source impedance............................................... 600 Ω
Load impedance.................................................. 600 Ω
Audio system performance
Frequency response ................20 to 20 KHz +/- 0.1 dB
Bandwidth....................................................... 100 KHz
S/N .........................105 dB ref +18 dBm 20 to 20 KHz
Crosstalk ........................ 80 dB @ 15 KHz (all hostile)
IM and TDH ......... 0.05 % to + 18 dBm 20 to 20 KHz
Optional control panel
Cable type .......................................... DB9M to DB9M
Maximum length...................................... 200 ft / 60 M
Mechanical characteristics
Frame depth ............................................8.5" / 21.6 cm
Operating temperature range ....................0 - 40 deg C
Input voltage .................. 117 VAC +/- 10 % 57-63 Hz
....................................or 230 VAC +/- 10% 47 - 63 Hz
Power req............................................................20 VA
Weight ...................................................10 lbs / 4.5 Kg
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MODEL 161 INSTRUCTION MANUAL
General description.
The Model 161 is a 16 input video plus stereo
audio single bus switching system. It can be
configured with a variety of control methods:
• Local front panel pushbutton control with 16
relegendable LED illuminated switches.
• Remote control panel pushbuttons with 16
relegendable LED illuminated switches, including
15M interconnect cable. Cables up to 150M are
available.
• Remote control panel pushbuttons with 16
relegendable incandescent lamped switches,
including 15M interconnect cable. Cables up to
150M are available.
• RS232/RS422 serial control.
Multiple controlling devices such as remote plus
local panels, pushbutton plus serial, more than one
serial controller, etc. can be used.
The electronics for the SVS Model 161 are contained in a 1 3/4" high EIA standard 1 RU high
rack mountable frame. All the circuitry is on a
single plug-in circuit board.
Installation.
Carefully unpack the system. If any damage to
the unit is observed, immediately contact both the
shipping company and SVS.
The Model 161 produces almost no heat, so it can
be mounted next to other equipment without the
need to allow space for cooling. Its shallow depth
(8.5") allows the space behind the Model 161 to
aid in the cooling of deeper heat producing equipment above or below it.
Power supply.
Power for the Model 161 is provided by an external outlet mounted transformer (117VAC version
only). For 220VAC units the external transformer
has a short input cable to which the proper AC
input connector must be added. The output of the
transformer is a 2M (6ft) cable with a 3 pin
female DIN connector. This mates with the
corresponding 3 pin male DIN connector on the
rear of the Model 161 labeled "PWR."
Audio connections.
Audio connections on the rear of the Model 161
are made via terminal strips. Each input and
output signal consists of 3 connections: +, -, and
G for ground. The terminal strip design is a type
that directly accepts the stripped end of a wire
without attaching any type of lug to the end of the
wire. When using stranded wire it is easier to
handle the wire if the stripped end is tinned to
avoid stray strands from touching other wires.
If the audio source is unbalanced (one wire with a
shield), connect the single wire to the "+" terminal
and the shield to the "G" terminal. Leave the "-"
terminal open.
If the audio source is balanced with no shield,
connect the two wires to the "+" and"-" terminal
and leave the "G" terminal open.
Video connections.
The 16 video input BNC connectors each have an
internal 75 ohm 1% termination. Unused inputs
can be left with no connection.
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MODEL 161 INSTRUCTION MANUAL
Control panels.
The local control panel if ordered with the unit
will be installed at the factory in place of the
blank front cover. If it is installed later, remove
the blank cover, connect one end of the short
ribbon cable with 9 pin D miniature connector to
the mating connector on the front edge of the
Model 161 circuit board. Attach the other end of
the ribbon cable to the D connector on the rear of
the control panel. Being careful not to pinch the
ribbon cable, slide the local control panel between
the top and bottom cover until it stops against the
two magnets at each end of the frame.
The remote control panel if ordered is a separate 1
3/4" high rack mount unit plus separate interconnect cable. After mounting the remote panel at
the desired location connect one end on the cable
to the connector labeled "REMOTE CONTROL"
at the rear of the Model 161 frame. Connect the
other end to the connector on the rear of the
remote panel.
CIRCUIT DESCRIPTIONS
Switching electronics.
The electronics for the Model 161 are all on a
single plug in module, the 503135. Refer to the
schematic diagram while reading the following
circuit description. The drawing is divided into 3
pages by circuit function. The following text is
organized the same way.
Video circuits (sheet 1 of 3 of the schematic
diagram). The 503135 has 16 identical video
crosspoints. The same component designators
and values are used for all 16 crosspoints. Only
one crosspoint is described here. Video input 1
enters the 503135 on edge connector J1 pin 1.
From there it is AC coupled through C1. C1
protects the circuitry of the 503135 from possible
damage if the incoming video signal were to have
an excessive DC component on it. R1, after C1,
provides a ground reference to the AC coupled
signal. The video crosspoint which follows is a
"T" circuit configuration. When a crossspoint is
off the two transistors in the signal path are both
off and the diode between them is on. This
provides very high attenuation (over 100db) of an
off inputs signal through the crosspoint. When a
crosspoint is on, both transistors in the signal path
are on and the diode between them is on. Thus
the desired video signal is allowed to pass on to
the common bus. The control of the crosspoints is
from the output of a 1 of 16 decoder. One output
of the decoder is always high, which is +12 Volts.
The decoder is powered by +12 V and -2 V,
which means the 15 outputs that are not at +12V
are at -2V.
When crosspoint 1 is off the control side of R4 is
at -2V. Because the anode of D1 is connected to
ground and D1 is in series with R4, their junction
will be at about -0.7V and D1 will be on. The
average voltage at the base of Q1 is 0.0V while its
emitter is at -0.7V. This causes the base emitters
junction of Q1 to be reverse biased and therefore
present a high impedance to the incoming signal
while D1 is a low impedance to the signal. This
produces a fairly high attenuation of the video
signal. Q2, as will be explained later, is also off
and further isolates the input signal when the
crosspoint is in the off state.
To turn on crosspoint one, the first output of the
control decoder changes from -2V to +12V. This
causes D1 to now be reverse biased and become a
high impedance. With 0.0V at the base of Q1 and
a positive voltage on R4, Q1 becomes an emitter
follower, buffering the input signal and raising its
DC level to +0.7V. Q2 is another emitter follower. R13 is its emitter resistor. Q2 lowers the
incoming signal level DC by the same amount it
was raised by Q1. This means the signal DC level
at the common bus of the output of the 16
crosspoints is approximately 0.0V. For an off
crosspoint where D1 is forward biased to -0.7V
the emitter base junction of Q2 is also reverse
biased by 0.7V. In this way Q2 is used in an off
crosspoint as the second series off switch, attenuating the input signal.
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MODEL 161 INSTRUCTION MANUAL
The output of the 16 crosspoints are tied to the
single pull down emitter resistor R13 and to an
output amplifier consisting of U2. U2 is a 50MHz
wide band video amplifier with a very low output
impedance (about 0.1 ohms). R15 in conjunction
with R14 + variable R11 sets the gain of the entire
503135 to 2X. R16 raises the output impedance
to 75 ohms required to interface to external 75
ohm coax cable environment.
The output of U2 is also fed to the sync separator
circuit Q4. Q4 is turned on by R19 except during
the negative extreme of sync on the video signal.
This results in 12 V P-P inverted sync at the
collector of Q4. U7B and U7C are connected
with R20 and C11 as a low pass filter which
separates vertical interval from the composite
sync output of Q4.
U7D functions in two modes depending on
whether or not sync is present. When sync is
present it is inverted by U7D and its trailing edge
is made into a switching pulse by U7E. When
there is no sync U7 pin 4 stays high. This is AC
coupled through C10, so the DC level at U7 pin 4
is not important. U7D now functions as a free
running oscillator. D2 and D3 allow the duty
cycle and period of the oscillator to be close to
vertical sync to prevent U7D from changing state
as an oscillator if it is driven by a signal at U7 pin
4.
The output of U7 pin 10 is a short positive pulse
at vertical interval line 6. This is used to clock the
latch portion of U1. U1 is a 4 bit latch and decoder. The 4 line control input to U1 is decoded
by U1 to select the desired 1 of 16 video
crosspoints.
Audio circuits. The 503135 has two identical
audio channels. One channel has its input and
output connections on edge connector J2. The
other channel uses exactly the same pin numbers
on J3. Only channel one is discussed here. The
audio circuits are on page 2 of the schematic
diagram. Each audio input is configured for a
balanced signal with two signal connections. R5/
R6 and R7/R8 divide the signal level in half and
provide a 40K ohm input impedance to the audio
signal.
U3 is a dual op-amp with each op-amp connected
to one of the input divider outputs. U3's only
function is to reduce the impedance from 5K
ohms (the parallel equivalent of each input divider) to less than a few ohms. The low impedance is needed to keep the unselected audio inputs
from crosstalking into the desired channel. The
outputs of the input buffer op-amps are connected
to two eight input dual channel analog switches,
U4 and U5. U4 and U5 have their outputs connected together and the control connected to
configure them as a sixteen by one balanced
switch. The balanced switching technique has a
number of advantages:
• Double the signal level for 6dB more dynamic
range.
• Common mode crosstalk is completely canceled
in the output amplifier.
• Using balanced audio and unbalanced video
prevents their interacting when they must exist in
the same environment.
• Switching transients are rejected by the output
amplifier resulting in a silent switch.
The output of the analog switches feeds U6 which
is both a common mode rejection circuit and a
6dB amplifier to make up for the loss of the input
attenuators.
Control circuits. The four latch circuits on the
503135 are each the same. The LSB latch will be
discussed here. Refer to page 3 of the 503135
schematic diagram. The circuit is made up of
U8A, U8F and its associated components. The
two hex Schmidt gates are connected in series to
form a non-inverter with R45 as positive feedback. With no input the circuit forces itself to
either 0 or +12V. When a control input is active
the controlling device puts a low impedance 0 or
+12V on the input to U8A. This overrides the
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MODEL 161 INSTRUCTION MANUAL
previous state of U8A and U8B. When the control input is removed the circuit stays in the last
level set at its input. R52 and C13 provide input
protection and noise rejection.
The output of the four latches connect directly to
the video latch/decoder described previously. The
audio switches operate on +/-7V. Q6 is connected
to the junction of U8A and U8F so that Q6's
output is in the same polarity as the video control
output of the latch except that the voltage swing is
+7 to -7V. The latch for the MSB drives two
level shift transistors for the audio because the
audio selectors are two separate 8 by 1's and each
requires a separate enable input.
Power supply. 24VAC center tapped is produced
by an external power transformer. The low
voltage AC enters the module on J3 pins 27 and
28. It is rectified by D6 through D8. C23 and
C24 are the positive and negative primary filters
respectively. U11 produces +12V for the video
circuits and control logic. U9 produces -12V for
the video circuits. U12 produces +12V for the
audio op-amps. R54 and D5 produce +7V for the
audio CMOS crosspoints and their control level
shifters. Similarly U10 and R53/D4 produce
negative voltages for the audio circuits.
LED Control panel.
503138 control panel. The 503138 is a 16 switch
circuit board which uses LED lamps and includes
switch encoding and lamp driver circuits. The
503138 is primarily used with the Model 161, 16
by 1 video plus stereo audio switcher.
Refer to the schematic diagram while reading the
following circuit description. The 16 switches are
connected together in a 4 by 4 matrix configuration. This allows U1, a keypad encoder, to be
used to convert the one-of-sixteen to a four bit
binary code. U1 also provides switch debounce
and key rollover which means that if two buttons
are both selected, only the first switch detected is
encoded until all switches are released. When no
switch is selected the output of U1 is a high
impedance. The latching circuit on the 503135
(the other end of the system), is a 23K ohm source
impedance. This medium impedance holds the
four data lines at either 0 or +12V. When a
switch is pushed the DA output of U1 is inverted
by Q1 and puts a low on the OE input of U1
causing the output of U1 to become a low impedance. This forces the 503135 logic to follow and
hold the selected four bit code.
The lamp circuit of the 503138 consists of U2, a
4 line to 16 line decoder. U2 operates on +5V
while the control lines swing from 0 to +12V.
R1/R2 (typical) attenuate the 12V swing to 5V.
The outputs of U2 drive the 16 LED's in the
switches. R12 limits the current in the LED's to
about 20MA.
The 503138 is power with unregulated DC. U3
provides regulated +12V for U1. U4 provides
+5V for U2 and the LED's.
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MODEL 161 INSTRUCTION MANUAL
Incandescent control panel.
The 803139 is a 16 switch assembly which uses
incandescent lamps and includes switch encoding
and lamp driver circuits. The 803138 is primarily
used with the Model 161, 16 by 1 video plus
stereo audio switcher.
Refer to the schematic diagram while reading the
following circuit description. The 16 switches are
connected together in a 4 by 4 matrix configuration. This allows U1, a keypad encoder, to be
used to convert the one-of-sixteen to a four bit
binary code. U1 also provides switch debounce
and key rollover which means that if two buttons
are both selected, only the first switch detected is
encoded until all switches are released. When no
switch is selected the output of U1 is a high
impedance. The latching circuit on the 503135
(the other end of the system), is a 23K ohm source
impedance. This medium impedance holds the
four data lines at either 0 or +12V. When a
switch is pushed the DA output of U1 is inverted
by Q1 and puts a low on the OE input of U1
causing the output of U1 to become a low impedance. This forces the 503135 logic to follow and
hold the selected four bit code.
The lamp circuit of the 803139 consists of U2, a
dual two line to four line decoder. The first half
of U2's outputs are current boosted by emitter
followers Q2 through Q5. Q6 through Q9 invert
the remaining outputs of U2. Q2 through Q9
connect to the incandescent lamps in the switches
in a four by four matrix fashion.
The 803139 is powered with unregulated DC. U3
provides regulated +12V for U1 and U2. A 47
ohm resistor limits in rush current to lamp driving
transistors Q2 through Q5.
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MODEL 161 INSTRUCTION MANUAL
PARTS LIST FOR ASSEMBLY NO. 503135
16 BY 1 VAA SWITCHER
REF DESCRIPTION
R1 22KΩ 1/4W 5% RESISTOR
R2,3 330 Ω 1/4W 5% RESISTOR
R4 10K Ω 1/4W 5% RESISTOR
D1 1N4148 DIODE
Q1 2N3906 PNP TRANSISTOR
Q2 2N3904 NPN TRANSISTOR
C1 22UF 15V TANTALUM CAPACITOR
THE ABOVE REPEATS 16 TIMES
R5,6,7,8 10K Ω 1/8W 1% RESISTOR
U3 MC1458 DUAL OP-AMP
THE ABOVE REPEATS 32 TIMES
R36,37,38,39, 10KΩ 1/8W 1% RESISTOR
40,41,42,43
R34,35 100Ω 1/4W 5% RESISTOR
U6 MC1458 DUAL OP-AMP
U4,5 MC14097 ANALOG SWITCH
THE ABOVE REPEATS 2 TIMES
R9,17,49,50,51,52 1K Ω 1/4W 5% RESISTOR
R10 4.7K Ω 1/4W 5% RESISTOR
R12 330 Ω 1/4W 5% RESISTOR
R13 2.2K Ω 1/4W 5% RESISTOR
R14 820 Ω 1/4W 5% RESISTOR
R15 1.3KΩ 1/4W 5% RESISTOR
R16 75 Ω 1/8W 1% RESISTOR
R18,31 10K Ω 1/4W 5% RESISTOR
R19 470K Ω 1/4W 5% RESISTOR
R20,21,23,25,27,29 100K Ω 1/4W 5% RESISTOR
R22,24,26,28,30 22K Ω 1/4W 5% RESISTOR
45,46,47,48
R32 2.2M Ω 1/4W 5% RESISTOR
R44 47K Ω 1/4W 5% RESISTOR
R53,54 470 Ω 1/4W 5% RESISTOR
U1 MC14514 DECODER (CD4514)
U2 EL2020 WIDE BAND AMPLIFIER
U7,8 MC14584 HEX SCHMIDT
U9,10 MC79M12 -12V 500MA REGULATOR
U11,12 MC78M12 +12V 500MA REGULATOR
D2,3 1N4148 DIODE
D4,5 IN755V ZENER DIODE
D6,7,8,9 1N4002 1 AMP DIODE
C3,4 22UF 15V TANTALUM CAPACITOR
C2,5,6,7,8,9,10,13,14 0.1 UIF CERAMIC CAPACITOR (+4)
15,16,17,18,19,20,22
C11 470PF MICA CAPACITOR
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MODEL 161 INSTRUCTION MANUAL
C12 100PF MICA CAPACITOR
Q3,4,5,6,7,8,9 2N3906 PNP TRANSISTOR
J4 9 PIN D CONNECTOR H2R09 RA28A
R11 1KΩ POTENTIOMETER 3296W-001-102
C23,24 4700UF 25V ALUMINUM CAPACITOR
(2) LARGE EJECTOR
(6) 4-40 X 1/4 PHILLIPS HEAD MS
(6) 4-40 HEX NUT
(2) MICA WASHER (FOR U9,U10)
(1) PC BOARD 403135
PARTS LIST FOR ASSEMBLY NO. 503138
16 BY 1 MODEL 161 LED SWITCH BOARD
REF DESCRIPTION
(16) NKK SWITCH JB 15LP3F
R1,3,5,7 100K Ω 1/4W 5% RESISTOR
R2,4,6,8 150K Ω 1/4W 5% RESISTOR
R9,10 22K Ω 1/4W 5% RESISTOR
R12 68 Ω 1/4W 5% RESISTOR
U1 74C922 KEYPAD ENCODER
U2 74HC4514 DECODER
U4 78L05 +5V 100MA REGULATOR
U3 78L12 +12V 100MA REGULATOR
C1,2,3,5 0.1UF CERAMIC CAPACITOR
C6 1.0 UF TANTALUM CAPACITOR
Q1 2N3904 NPN TRANSISTOR
(1) 9 PIN D CONNECTOR (FEMALE)
(2) 3/16 X 1/2 4-40 SPACER
(2) JACK SOCKET
(2) 4-40 X 1/4 4-40 PHILLIPS SCREW
(1) 403138 PC BOARD
(1) 103073 FRONT PANEL
(1) 4-40 3/16X1/4 NYLON SPACER
PARTS LIST FOR ASSEMBLY NO. 503139
16 BY 1 PANEL CONTROL LOGIC
QTY DESCRIPTION
6 22KΩ 1/4W 5% RESISTOR
4 4.7KΩ 1/4W 5% RESISTOR
1 47Ω 1/4W 5% RESISTOR
8 MPSA13 NPN TRANSISTOR
1 2N3904 NPN TRANSISTOR
1 0.1UF CERAMIC CAPACITOR
1 1UF/35V TANTALUM CAPACITOR
1 78L12 +5V 100MA REGULATOR
1 MC14555 DUAL 2 TO 4 DECODER
1 74C922 KEYPAD ENCODER
1 205734-4 FEMALE 9 PIN D CONNECTOR
1 16 POSITION FEMALE HEADER
2 3/16 X 1/2 4-40 SPACER
2 4-40 X 1/4 PHILLIPS SCREW
2 JACKSOCKETS
1 403139 PC BOARD
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