Kramer VM-2N User manual

KRAMER ELECTRONICS LTD.
KRAMER ELECTRONICS, Ltd.
USER MANUAL
Video/Audio Distribution Amplifiers
Models:
VM-2N, VM-5S, VM-50A,
VM-50H, VM-50V, VM-50YC
IMPORTANT: Before proceeding, please read paragraph entitled
"Unpacking and Contents"

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Table Of Contents
Section Name Page
1INTRODUCTION 1
1.1 A Word On Distribution Amplifiers 1
1.2 Factors Affecting Quality of Results 1
2Specifications 2
3How Do I Get Started?4
4Unpacking and Contents 4
4.1 Optional Accessories 4
5VM Series Amplifiers 6
5.1 Getting To Know Your VM-2N 6
5.2 Getting To Know Your VM-5S Amplifier 7
5.3 Getting To Know Your VM-50A Amplifier 8
5.4 Getting To Know Your VM-50H Amplifier 9
5.5 Getting To Know Your VM-50YC Amplifier 11
5.6 Getting To Know Your VM-50V Amplifier 12
6INSTALLATION 13
7Connecting To VIDEO Devices 13
8Connecting To audio Devices 13
9Using The VM VIDEO/AUDIO AMPLIFIERS 13
9.1 Powering On The Amplifier 13
9.2 Looping 13
9.3 Coupling 14
9.4 Coupling Selection 14
9.5 Audio Level Control 14
9.6 Installing aVM Amplifier In a Mixed AC/DC Video/Audio System 15
10 Taking Care Of Your Amplifier 16
11 TROUBLESHOOTING 16
11.1 Power And Indicators 16
11.2 Audio Signal 17
11.3 Video Signal 19
List Of Illustrations
Figure Page
1 VM-2N Front/Rear Panel Features 7
2 VM-5S Front/Rear Panel Features 8
3 VM-50A Front/Rear Panel Features 9
4 VM-50H Front/Rear Panel Features 10
5 VM-50YC Front/Rear Panel Features 11
6 VM-50V Front/Rear Panel Features 12
7 J2 Internal Jumper Location 14
8 Installing a VM Amplifier In a Mixed AC/DC Video/Audio System 15
9 Locating The Internal Fuses 18
List Of Tables
Table
1VM-2N Front/Rear Panel Features 7
2VM-5S Front/Rear Panel Features 8
3VM-50A Front/Rear Panel Features 9
4VM-50H Front Panel Features 11
5VM-50H Rear Panel Features 11
6VM-50YC Front/Rear Panel Features 12
7VM-50V Front/Rear Panel Features 13

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1. INTRODUCTION
Congratulations on your purchase of this Kramer Electronics amplifier. Since 1981 Kramer has
been dedicated to the development and manufacture of high quality video/audio equipment.
The Kramer line has become an integral part of many of the best production and presentation
facilities around the world. In recent years, Kramer has redesigned and upgraded most of the
line, making the best even better. Kramer’s line of professional video/audio electronics is one of
the most versatile and complete available, and is a true leader in terms of quality, workmanship,
price/performance ratio and innovation. In addition to the Kramer line of high quality amplifiers,
such as the one you have just purchased, Kramer also offers a full line of high quality switchers,
processors, interfaces, controllers and computer-related products. This manual includes
configuration, operation and option information for the following products from the Kramer VM
line of distribution amplifiers. All these VM amplifiers are similar in operation and features.
 VM-2N- 1:2 Video/Audio Distributor
 VM-5S- 1:5 Video/Audio Distributor
 VM-50A- 1:5 Audio Distributor
 VM-50H- 1:5 Headphone Distributor
 VM-50V- 1:5 Video Distributor
 VM-50YC-1:5 s-Video Distributor
1.1 A Word On Distribution Amplifiers
Distribution amplifiers are used to distribute one source to several acceptors for simultaneous
recording or monitoring of one source, with no discernible signal degradation. They vary in the
number of inputs, looping capability, programming capability, number of outputs, operating
format, bandwidth and input/output coupling. A good quality distribution amplifier amplifies
the incoming signal, pre-compensates the signal for potential losses (resulting from the use of
long cables, noisy source, etc.) and generates several identical buffered and amplified outputs.
1.2 Factors Affecting Quality of Results
There are many factors affecting the quality of results when signals are transmitted from a
source to an acceptor:
Connection cables - Low quality cables are susceptible to interference, they degrade signal
quality due to poor matching and cause elevated noise levels. They should therefore be of the
best quality.
Sockets and connectors of the sources and acceptors - So often ignored, they should be of
highest quality, since "Zero Ohm" connection resistance is the target. Sockets and connectors
also must match the required impedance (75 ohms in video). Cheap, low quality connectors
tend to rust, thus causing flaws in the signal path.
Amplifying circuitry - Must have quality performance when the desired end result is high
linearity, low distortion and low noise operation.
Distance between sources and acceptors - Plays a major role in the final result. For long
distances (over 15 meters) between sources and acceptors, special measures should be taken in
order to avoid cable losses. These include using higher quality cables or adding line amplifiers.
Interference from neighboring electrical appliances - These can have an adverse effect on signal
quality. Balanced audio lines are less prone to interference, but unbalanced audio should be
installed far from any mains power cables, electric motors, transmitters, etc. even when the
cables are shielded.

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2. SPECIFICATIONS
VM-2N VM-5S VM-50A
Configuration 1:2 1:5 1:5
Input Type 1 Composite/single
component video
1 stereo audio/balanced
mono
1 video (internally selected)
looping (composite, single
component or serial digital)
1 stereo audio/balanced
mono
1 stereo audio
Input Connections BNC connector (video)
RCA connector (audio)
BNC connector with rear
t
ermination switch (video)
RCA connector (audio)
RCA
Input Level 1Vpp/75ohm (video)
+4dBm/50kohm (audio)
1Vpp/75ohm on (video)
up to 21V/50kohm (audio)
Looping +4dbm/50kohm
Output Type 2 video
2 stereo audio/balanced
mono
5 video (composite, single
component or serial digital)
5 stereo audio/balanced
mono
5 stereo audio
Output Connector BNC connector (video)
RCA connector (audio)
BNC connector (video)
RCA connector (audio)
RCA connectors
Output Level 1Vpp/75 (video)
+4dBm/50ohm (audio)
1Vpp/75ohm (video)
up to 21V/220ohm (audio)
+4dBm/100ohm
Output Coupling DC (video)
AC (audio)
DC/AC internally selectable AC
S/N Ratio Better than 85dB(audio)
75dB (video)
> 82dB @ 1V (audio)
75dB (video)
83db unweighted
Audio Bandwidth >100KHz, 0 -1db points 100 kHz 50khz, -3db
Video Bandwidth Exceeding 400 MHz. Exceeding 350 MHz. NA
Max audio Output >24dBm +20dBm 25Vpp
Max video Output 1.5Vpp 1.7Vpp NA
Differential Gain 0.05% 0.05% NA
Differential Phase 0.1Deg. 0.1Deg. NA
Audio THD+N 0.017% 0.009% <0.018%
Second harmonic 0.002% @ 1KHz 0.001% @ 1KHz 0.003%
K-Factor <0.05% <0.05% NA
SDI eff. Range Up to 50 meters Up to 70 meters NA
Dimensions (W, D, H) 16.5cm x 12cm x 4.5cm
6.5" x 4.72" x 1.77"
22cm x 18cm x 4.5cm
8.66" x 7.08" x 1.77"
16.5cm x 12cm x 4.5cm
6.5" x 4.72" x 1.77"
Weight 0.620Kg (1.3lbs) Approx. 1.40Kg (3.3lbs.) Approx. 0.62Kg (1.4lbs) Approx.
Power consumption 4.6VA 3.5VA 0.78VA
Power Source 230VAC/50Hz, (115V
USA)
230VAC, 50Hz, (115V
USA)
12VDC, 40mA

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SPECIFICATIONS (continued)
VM-50H VM-50YC VM-50V
Configuration 1:5 1:5 1:5
Input Type 1 stereo audio 1 s-video, looping 1 video, looping
Input Connections 6.5-mm stereo phone
sockets
4P connectors with a
termination switch
BNC connector with
termination switch
Input Level 1Vpp/50kohm 1Vpp/75ohm (Y),
0.3Vpp/75ohm (C)
1Vpp/75ohm
Output Type 5 stereo audio 5 s-video, looping 5 video
Output Connector 6.5-mm stereo phone
sockets
4P connectors BNC connectors
Output Level 250mW/8ohm 1Vpp/75ohm (Y),
0.3Vpp/75ohm (C)
1Vpp/75ohm
Output Coupling AC AC AC
S/N Ratio Better than 78dB 80.5dB 73db
Audio Bandwidth 20-100,000 Hz. -3dB NA NA
Video Bandwidth NA 280 MHz -3dB (Y) 480MHz -3dB
Max audio Output 8Vpp NA NA
Max video Output NA 2Vpp (Y) 2Vpp
Differential Gain NA 0.05% 0.05%
Differential Phase NA 0.05Deg 0.12Deg
Audio THD+N Less than 0.08% @
100mW
NA NA
K-Factor NA <0.1% <0.05%
Level Controls 5 stereo output level
controls (front), 1 mono
switch (rear)
Y control: Range: -1.6 to
3.3db
C Control: -1.6 to 3.3db
Gain Range = -0.8 to 1.9db
EQ. control: 0 to 3.2db
Gain Range 70db (-60db to +10db) -1.6 to 3.3dB -0.8 to 1.9dB
Dimensions
(W, D, H)
16.5cm x 12cm x 4.5cm
6.5" x 4.72" x 1.77"
16.5cm x 12cm x 4.5cm
6.5" x 4.72" x 1.77"
16.5cm x 12cm x 4.5cm
6.5" x 4.72" x 1.77"
Weight 0.68Kg (1.5lbs) 0.58Kg (1.3lbs.) 0.62Kg (1.4lbs.)
Power consumption 15VA 0.6VA 0.48VA
Power Source 12VDC, 1.15A 12VDC, 50mA 12VDC, 40mA

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3. HOW DO I GET STARTED?
The fastest way to get started is to take your time and do everything right the first time. Taking
15 minutes to read the manual may save you a few hours later. You don’t even have to read the
whole manual. At the beginning of each section, you’ll find an overview of the section. So if the
section doesn’t apply to you, you don’t have to spend your time reading it.
4. UNPACKING AND CONTENTS
The items contained in your Kramer VM amplifier package are listed below. Please save the
original box and packaging materials for possible future transportation and shipment of the
amplifier.
 Desktop size amplifier
 AC power cable (where applicable)
 User’s Manual
 Rubber feet
 Kramer concise product catalog
For additional information regarding optional cables and additional accessories, contact your
Kramer dealer.
4.1 Optional Accessories
The following Kramer accessories can enhance implementation of your amplifier.
 Rack Adapter - Used to adapt non-standard size machines to a standard 1U rack. One or
more machines may be installed on each adapter.
 BNC "Y" Connector - Used for looping purposes and splits the incoming signal to enable
connection of an additional machine.
 Termination Plug - Used to terminate the line to 75ohm for proper matching.
 SP-40 - (video/audio Processor) Serially connected between the video/audio source and
the VM amplifier for video and audio processing. The machine is a high quality processor
used for video control and correction in duplication and production studios, camera control,
luminance and white balance correction. The SP-40 is capable of Composite to Y/C
conversion and bi-directional transcoding. The machine allows video gain control down to full
fade, definition control, contrast control, color saturation control, black level control, audio
mix control for mixing between the selected source and an audio AUX source and a screen
splitter control for “before-after” comparison. The unique limiter switch in the SP-40 allows
true signal limiting and special effects.
 SP-11 - (video/audio Processor) can be serially connected between the video/audio source
and the VM amplifier for video and audio control/correction. The machine provides camera
control and luminance/white balance correction. The SP-11 is also capable of performing
composite to Y/C conversion and bi-directional transcoding. The machine allows full control
over the video signal: video gain down to full fade, log or linear definition control, log or
linear contrast control, color saturation control, black level control, red, green and blue
controls and a screen splitter control for “before-after” comparison. The Input switch control
is "audio-follow-video".

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 104L - (video Line Amplifier) Serially connected between the video source and the VM
amplifier for video processing, the machine is used for video line amplification and cable
compensation, video field work and SDI signal distribution. Signal loss and the resulting
depreciation in picture quality is a real problem in any video setup requiring considerable
distance between video source and acceptors. The KRAMER 104L video Line Amplifier, one
of the KRAMER TOOLS, is a high quality amplifier, which prevents video signal losses over
long cables. For best results the 104L amplifier is installed adjacent to the video source. The
104L is housed in the compact KRAMER TOOLS enclosure and is fed by a 12VDC source.
High bandwidth and front accessible controls make it suitable for the most demanding analog
and SDI studio applications.
 VM-9YC - (video/audio Line Amplifier) Serially connected between the video/audio
source and the VM amplifier for video and audio processing, the machine is a high quality
video/stereo amplifier which compensates for video and audio signal losses when long cables
are used. In any video/audio setup requiring considerable distances between video/audio
source and acceptors, signal loss and thus depreciation in the quality of both picture and
sound is a real problem. To prevent this phenomenon, a VM-9S amplifier is installed adjacent
to the video/audio source.
 VM-4E - (A Precision Mechanical 4x4 video/audio Switcher) Several video/audio sources
may be connected to its inputs for switching. The machine may be used in every application
where easy and fast video and audio source selection is needed and for high isolation between
inputs. All unselected inputs are internally terminated with 75-Ohm resistors. The VM-4E
switches video, SDI and any other high frequency signals. The VM-4E is housed in a small
enclosure, occupying very little desk space.
 VM-81AV - (A Precision Mechanical 8x1 video/stereo audio Switcher) Several
video/audio sources may be connected to its inputs for switching. The machine offers fast
and easy video/audio source and acceptor selection. The VM-81AV provides high isolation
between inputs and outputs and all unselected video inputs are internally terminated with
75-Ohm resistors. The VM-81AV is housed in a professional 19" rack mountable enclosure.
 VS-801xl- (8:1 Composite/Single Component video & Unbalanced audio Switcher)
Several video/audio sources may be connected to its inputs for switching. The machine
provides truly effortless switching between eight video and unbalanced audio inputs and one
output. Switching is done during vertical interval, either of source no. 1 or of the video
available on the external sync socket. The switcher may be controlled by touch buttons or by
contact closure via a remote socket on the back of the machine. video signal bandwidth is 225
MHz (typical), allowing the machine to be used in the most demanding applications.
 TP-1 (video Line Transmitter) If a DA output is sent over a long distance (100 meter or
more), it is necessary to convert the signal to twisted pair type. The TP-1 sends a color video
signal over long distances using telephone wire or any other twisted pair wire thus extending
the range of operation of a DA. The TP-1 maintains the bandwidth of an industrial color
video signal up to several hundred meters and of broadcast quality (up to 12 MHz) signals up
to 100 meters. At shorter distances, as in a studio, bandwidth of 30MHz is easily achieved.
By using the KRAMER TP-1 together with the TP-2 (video Line Receiver) coax wiring (in a
studio, for example) can be completely eliminated. The TP-1 can also be used for

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simplification of security and CCTV installations, and for teleconferencing in offices and
hospitals using existing intercom or telephone wiring.
 VA-11AV - (video/audio Combiner) Used to distribute video/audio signals. The machine
can be inserted in front of a DA, allowing the DA to distribute a video signal and two audio
signals simultaneously. It sends a color video signal and a stereo audio signal using only one
standard coax cable in real time. The machine maintains the bandwidth of an industrial color
video signal and the output signal may be viewed and recorded as a normal video signal. By
using the VA-11AV together with the VA-12AV (video/audio Separator) the audio stereo
signal may be recovered so audio signals may be sent in a hidden mode, to be recovered only
by the VA-12AV. The VA-11AV can be used for simplification of security and CCTV
installations, using existing video coax wiring for video and audio transmissions.
 611T/611R - (611T Fiber Optic Transmitter and 611R Fiber Optic Receiver) Part of the
KRAMER TOOLS series, and designed for studio and other demanding applications, these
machines, in combination, may be used to send one of the distributed channels to distances
of 5-25Km. The full bandwidth 611T and matching 611R use state-of-the-art fiber optic
circuitry and allow the user (via rear panel trimmers) to adjust input and output video levels
and high frequency peaking to achieve best performance.
 VIDEO TESTER - A new, unique, patented, indispensable tool for the video professional,
the video Tester is used to test a video path leading to/from an amplifier. By pressing only
one touch switch it can trace missing signals, distinguish between good and jittery (VCR
sourced) signals, and identify the presence of good signals. Whenever a video signal is missing,
because of bad connections, cable breaks or faulty sources, the video Tester is all you need.
5. VM SERIES AMPLIFIERS
This section describes all the controls and connections of your amplifier. Understanding all of
the controls and connections helps you realize its full power.
5.1 Getting To Know Your VM-2N
The KRAMER VM-2N is an ultra-high bandwidth, state-of-the-art video/stereo audio
Distribution Amplifier designed for analog and digital studio applications. The VM-2N splits a
single input source, be it composite, single component or Serial Digital video, into two identical
outputs with no discernible signal degradation. video output signals are DC coupled. The audio
can be either unbalanced stereo or balanced mono, as the audio performance and levels of the
VM-2N are appropriate for use in the most demanding applications.
Front/Rear panel features of the VM-2N are described in Figure 1and Table 1.
NOTE
For operation instructions refer to section 9.1.

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Figure 1: VM-2N Front/Rear Panel Features
Table 1: VM-2N Front/Rear Panel Features
No. Feature Function
1. Illuminated power switch (on
front panel)
Supplies power to the unit.
2. VIDEO IN BNC connector video input
3. OUT 1-OUT 2 BNC connectors 2 amplified and buffered video outputs.
4. AUDIO IN RCA connectors
(L, R)
audio input
5. OUT 1-OUT 2 RCA audio
connectors (L, R)
2 amplified and buffered audio outputs.
6. Power connector
A 3-prong AC connector allows power to be supplied
to the unit. Directly underneath this connector, a fuse
holder houses the appropriate fuse.
5.2 Getting To Know Your VM-5S Amplifier
The KRAMER VM-5S, an upgrade of the VM-6NS, is an ultra-high bandwidth, video/stereo
audio Distribution Amplifier designed for analog and digital studio applications. The VM-5S
splits a single input source - composite, single component or Serial Digital video - into five
identical outputs. video output signals can be AC or DC coupled (factory default is DC) and
inputs can be looped through using an external termination switch. The audio can be either
unbalanced stereo or balanced mono. The machine is housed in a half 19" wide enclosure, and
two machines may be mounted side-by-side in a 1U 19" rack space using an optional adapter.
Front/Rear panel features of the VM-5S are described in Figure 2and Table 2.
NOTE
For operation instructions refer to sections 9.1, 9.2.

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Figure 2: VM-5S Front/Rear Panel Features
Table 2: VM-5S Front/Rear Panel Features
No. Feature Function
1. Illuminated power switch (on
front panel)
Supplies power to the unit.
2. VIDEO IN BNC connector video input
3. TERM pushbutton Selects "75ohm" or "HI-z" impedance
(pressed=75ohm). For looping select "Hi-z".
4. OUT 1-OUT 5 BNC connectors 5 amplified and buffered video outputs.
5. AUDIO IN RCA connectors
(LEFT, RIGHT)
audio input
6. OUT 1-OUT 5 RCA connectors
(L, R)
5 amplified and buffered audio outputs.
7. Power connector
A 3-prong AC connector allows power to be
supplied to the unit. Directly underneath this
connector, a fuse holder houses the appropriate fuse.
5.3 Getting To Know Your VM-50A Amplifier
The KRAMER VM-50A is a high quality, state-of-the-art stereo audio Distribution Amplifier
designed for studios, shops, showrooms and other demanding applications.
The VM-50A splits a single stereo input source into five identical outputs. The VM-50A uses an
external 12V DC power source, and therefore is suitable for fieldwork as well. The machine has
unique built-in circuitry, which allows high signal level processing even while using a 12VDC
power source. The VM-50A machine is a perfect match to the VM-50V/50YC video/s-video
DAs.
Front/Rear panel features of the VM-50A are described in Figure 3 and Table 3:
NOTE
For operation instructions refer to sections 9.1, 9.2.

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Figure 3: VM-50A Front/Rear Panel Features
Table 3: VM-50A Front/Rear Panel Features
No. Feature Function
1. Illuminated power switch (on
front panel)
Supplies power to the unit.
2. IN (L, R) RCA connectors Audio input.
3. LOOP in RCA connectors Provides audio looping capability to increase number of
outputs.
4. OUTPUTS 1-5 RCA
connectors
5 amplified and buffered audio outputs.
5. 12VDC feed connector A DC connector that allows power to be supplied to the
unit. An internal fuse holder houses the appropriate fuse
(see location of fuse in Figure 9).
5.4 Getting To Know Your VM-50H Amplifier
The KRAMER VM-50H is a high quality, state-of-the-art, stereo Headphone Distribution
Amplifier designed for studios, shops, showrooms, museums and audio fieldwork.
The VM-50H splits a single stereo input source into five identical outputs, each output level is
individually controllable. The VM-50H uses an external 12VDC power source, and therefore is
suitable for fieldwork as well. The VM-50H can drive low impedance headphones or 5 stereo
sets of small loudspeakers. The machine has a mono switch and thus can deliver 10 identical
mono outputs instead of 5 stereo outputs.
Front/Rear panel features of the VM-50H are described in Figure 4, Table 4 and Table 5.
NOTE
For operation instructions refer to sections 9.1and 9.5.

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Figure 4: VM-50H Front/Rear Panel Features
Table 4: VM-50H Front Panel Features
No. Feature Function
1. Illuminated power switch (on
front panel)
Supplies power to the unit.
2. LEVEL CONTROL (Out1-
Out5) knobs
Control audio output level of outputs 1-5.
Table 5: VM-50H Rear Panel Features
No. Feature Function
1. Input 6.5mm socket audio input
2. Mono pushbutton Converts 5 stereo audio outputs to 10 mono outputs
when pressed.
3. Out 1- Out 5 6.5mm socket 5 amplified and buffered audio outputs.
4. 12VDC feed connector A DC connector that allows power to be supplied to the
unit. An internal fuse holder houses the appropriate fuse
(see location of fuse in Figure 9).

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5.5 Getting To Know Your VM-50YC Amplifier
The KRAMER VM-50YC is a high quality, state-of-the-art, s-video Distribution Amplifier
designed for studios, shops, showrooms and other demanding applications. The VM-50YC splits
a single input source into five identical outputs. The VM-50YC uses an external 12VDC power
source, and therefore is suitable for fieldwork as well. Dozens of copies of videotapes can be
made at the same time using several VM-50YC units chained through the looping inputs.
Front/Rear panel features of the VM-50YC are described in Figure 5 and Table 6.
NOTE
For operation instructions refer to sections 9.1, 9.2.
Figure 5: VM-50YC Front/Rear Panel Features
Table 6: VM-50YC Front/Rear Panel Features
No. Feature Function
1. Illuminated power switch (on
front panel)
Supplies power to the unit.
2. Hi-Z/75 Ohms switch Selects "75ohm" or "HI-z" impedance
(pressed="75ohm"). For looping select "Hi-z".
3. Input 4p connector video input
4. LOOP 4p connector Provides video looping capability to increase number of
outputs.
5. OUTPUTS 1- 5 4p
connectors
5 amplified and buffered video outputs.
6. 12VDC feed connector A DC connector that allows power to be supplied to the
unit. An internal fuse holder houses the appropriate fuse
(see location of fuse in Figure 9 ).

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5.6 Getting To Know Your VM-50V Amplifier
The KRAMER VM-50V is a high quality, state-of-the-art, video Distribution Amplifier designed
for studios, shops, showrooms and other demanding applications. The VM-50V splits a single
input source into five identical outputs. The VM-50V uses an external 12VDC power source,
and therefore is suitable for fieldwork as well. Dozens of copies of videotapes can be made at the
same time using several VM-50V units chained through the looping inputs.
Front/Rear panel features of the VM-50V are described in Figure 6 and Table 7.
NOTE
For operation instructions refer to sections 9.1, 9.2.
Figure 6: VM-50V Front/Rear Panel Features
Table 7: VM-50V Front/Rear Panel Features
No. Feature Function
1. Illuminated power switch
(on front panel)
Supplies power to the unit.
2. Hi-Z/75 Ohms switch Selects "75ohm" or "HI-z" impedance
(pressed="75ohm"). For looping select "Hi-z".
3. INPUT BNC connector video input
4. LOOP BNC connector Provides audio looping capability to increase number of
outputs.
5. OUTPUTS 1- 5 BNC
connectors
5 amplified and buffered video outputs.
6. 12VDC feed connector A DC connector that allows power to be supplied to the
unit. An internal fuse holder houses the appropriate fuse
(see location of fuse in Figure 9).

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6. INSTALLATION
The amplifier is provided with four rubber feet packed in a separate bag. Fit the feet to the unit,
place it on the table remote from heat generating sources and make the required connections.
Use a rack adapter in case a rack installation is required (see section 4.1 "Rack Adapters"), in
which case do not attach the feet.
7. CONNECTING TO VIDEO DEVICES
Video sources and output devices (such as amplifiers or recorders) may be connected to the
amplifier through the BNC connectors (VM-2N, VM-5S and VM-50V models) or 4p type
connectors (VM-50YC model) located at the back of the machine. Please keep in mind that the
output signal format will match that of the input signal format. All signal connections that use
more than one cable interconnecting between devices should be of equal length.
8. CONNECTING TO AUDIO DEVICES
Audio sources and output devices (such as amplifiers or recorders) may be connected to the
amplifier through the RCA type connectors (VM-2N, VM-5S) and through 6.5mm phone
sockets (VM-50H) located at the back of the machines.
9. USING THE VM VIDEO/AUDIO AMPLIFIERS
9.1 Powering On The Amplifier
NOTES
1. Amplifier should only be powered on after all
connections are completed and all source devices
have been powered on. Do not attempt to connect
or disconnect any video, audio or control signals
to the amplifier while it is powered on!
2. The socket-outlet should be near the equipment
and should be easily accessible. To fully
disconnect equipment, remove power cord from
its socket.
1) Press the toggle switch on the far-left front panel to the up position. In the up position, the
toggle switch glows, and the active input button illuminates as well.
2) Operate the acceptors.
9.2 Looping
The looping function enables the operator to extend the number of outputs per input. The
following example describes looping performed by using 3 amplifiers with one input and 5
outputs each: A video signal reaches input of amplifier No. 1. From looping connector of
amplifier No. 1 a cable is connected to input socket of amplifier No. 2. The loop output of
amplifier No. 2 is connected to the input socket of amplifier No. 3. In this way the input signal
is divided into 15 separate output signals. The operator must always switch to "Hi-z" the
termination switch of all the amplifiers but the last. The last amplifier’s termination switch
should always be at "75ohm" to maintain well-matched video line (of 75ohm impedance) from
first to last amplifier. Note that if looping function is not used, the termination switch should be
set to "75 ohm".

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9.3 Coupling
The coupling function enables the operator to determine whether the incoming video signal is
DC or AC coupled. When DC coupling is selected and proper standard video signal is applied to
the amplifier’s input, the output signal is equal to the input signal. When AC coupling is
selected, DC components of the incoming signal are removed. DC coupling is always preferable
since AC coupling might cause some linearity distortions in low and high frequencies (due to
non-ideal behavior of capacitors). A problem may arise when the incoming signal is riding on a
DC offset especially when the acceptors are highly effected by deviation of DC offsets (A to D
converters for example), which in turn results in a distorted picture.
9.4 Coupling Selection
(VM-5S Only)
The VM-5S comes with a DC coupling from the factory. Selecting AC Coupling is performed by
removing J2 internal jumper. To remove jumper, perform the following steps:
1) Using a Philips screwdriver, remove the Philips head screws from the cover and remove the
cover.
2) Locate J2 internal jumper on the internal printed board (see Figure 7) and remove it.
3) Reinstall the cover.
Figure 7: J2 Internal Jumper Location
9.5 Audio Level Control
(VM-50H Only)
To enable stereo audio control, verify that the "Mono" button is released. Then gently adjust the
LEVEL CONTROL Gain knobs to control the appropriate output audio gain to achieve
satisfactory audio level. To enable mono audio level control, select "Mono" position by pressing
the "Mono" pushbutton. Then, using the LEVEL CONTROL Gain knobs, adjust gently the
audio stereo level to achieve satisfactory audio level.
J2
INTERNAL JUMPER

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9.6 Installing a VM Amplifier In a Mixed AC/DC Video/Audio System
Video accessories use two basic forms of connection to sources and acceptors: AC coupled or
DC coupled. Each form has its own advantages and downbacks. DC coupling provides a non-
distorted signal, transferring accurately the DC contents of input signals to the outputs. AC
coupling suffers from problems related to bad quality, low frequency response and the
"breathing" effect. However, AC coupling isolates the acceptors from an erroneous DC level
sometimes found in video sources. If a video acceptor is too sensitive to the DC content
transferred to it via the DA from the source, AC coupling is preferred. AC coupling may be
initiated by either using a "AC/DC" coupling switch available on some of the video DAs, or
adding DC-removing components externally.
Perform the following steps (if necessary):
1) Connect the video source to the DA.
2) Add external coupling capacitors to each output of the DA that needs AC coupling.
3) Connect the acceptors to the outputs of the DA. Connect the DC coupled acceptors directly
and connect the AC coupled acceptors via back to back connected 1000µF/25V capacitors
(See Figure 8).
A useful tip:
The capacitor may be "stitched" on the coaxial cable directly, by carefully separating the shield
from the signal leading conductor, cutting this conductor and connecting the capacitor serially.
Figure 8: Installing a VM Amplifier In a Mixed AC/DC Video/Audio System

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10. TAKING CARE OF YOUR AMPLIFIER
Do not locate your amplifier in an environment where it is susceptible to dust or moisture.
These may damage the electronics, and cause erratic operation or failure. Do not locate your
amplifier where temperature and humidity may be excessive. Do not clean your amplifier with
abrasives or strong cleaners. Doing so may remove or damage the finish, or may allow moisture
to build up. Take care not to allow dust or particles to build up inside unused or open
connectors.
11. TROUBLESHOOTING
NOTES
1. Please note that if the output signal is disturbed or
interrupted by very strong external electromagnetic
interference, it should return and stabilize when such
interference ends. If not, turn the power switch off and on
again to reset the machine.
2. If the recommended actions still do not result in
satisfactory operation, please consult your KRAMER
Dealer.
11.1 Power And Indicators
Problem Remedy
No Power 1. Confirm that the rocker switch is in the “ON” position, and that
the red LAMP/LED is illuminated.
2. Confirm that power connections are secured at the amplifier and
at the receptacle. Make sure the receptacle is active, outputting
the proper mains voltage.
 For models VM-50A, VM-50H, VN-50V, VM-50YC,
perform the following:
1. Using a Philips screwdriver, remove screws attaching the
machine's cover.
2. Locate fuse holder located inside your amplifier (see Figure 9).
Confirm that the fuse is good by looking for the wire connected
between the ends of the fuse. If this wire is broken, replace fuse
with another, with the same rating.
3. Install cover by tightening the Philips screws.
 For models VM-2N, 5S, perform the following:
Remove power cord from AC outlet and the machine and then
using a flat head screwdriver, remove fuse holder located directly
below the power connector on your amplifier. Confirm that the
fuse is good by looking for the wire connected between the ends
of the fuse. If the wire is broken, replace the fuse with another,
with the same rating.

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11.2 Audio Signal
(VM-2N, VM-5S, VM-50A, VM-50H Only)
Problem Remedy
No audio at the Output
Device, Regardless of
Input Selected
1. Confirm that your sources and output device are powered on and
connected properly. Audio signals connected to the input of your
amplifier should be properly wired to the output of your source.
Audio signals connected to the output of your amplifier should be
properly wired to the input of your amplifier or recorder.
2. Confirm that any other amplifiers in the signal path have the
proper input and/or output selected. Pay special attention to input
amplifiers that may be built into your amplifier or recording
device.
Audio level is too low 1. Confirm that the connecting cables are of high quality and
properly built. Take special care in noting the wiring configuration
of balanced to unbalanced cables.
2. Check level controls located on your source input device or
output device.

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Figure 9: Locating The Internal Fuses
VM-50A fuse
VM-50H fuse
VM-50YC fuse
VM-50V fuse