Multiplex Technology CHANNEL PLUS 3445 - Manual (Page 3)

6
Things to watch for:
No picture
Weak ChannelPlus UHF channel
Audio volume is low
… Verify that the video source is on and is producing a video signal. Check that the
TV and the modulator are tuned to the same channel. For example, if the modulator is
broadcasting on UHF channel 16, make sure the TV is on UHF 16 rather than CATV 16. UHF 16
and CATV 16 are at different frequencies.
… If the TV has a separate UHF input, be sure that it is
connected.
… The left and right audio inputs are combined for monaural. For proper
audio level, both right and left inputs must be used. If you have a mono source, connect it to both
right and left inputs using an RCA ‘Y’ connector.
See the section on programming.
light IR DATA
IR DATA
LEDs blink
Herringbone interference on ChannelPlus channel (diagonal lines)
Herringbone interference on many channels, including ChannelPlus
channels (disappears when you remove the CATV/Ant feed)
No color on ChannelPlus channels
... You need to have one unused channel space between channels. The display will
blink if you have made an ‘illegal’ choice. See the section on programming.
...
You may have chosen a channel number that is not completely vacant. Distant UHF stations may
be un-watchable, but will cause interference if you try to create a new channel at the same
frequency. Also, cable companies often have extra signals where there should be none. Try
moving the ChannelPlus channel to another number. You may have to add a low pass filter to
remove cable company noise. If a filter does not work, try adding a DC-block to remove common
mode interference.
… The RF amplifier can be
overloaded by abnormally strong signals. Often, you can cure the problem with a simple
attenuator. Use a variable attenuator and try to find a signal level where the interference just
disappears. Sometimes, the problem is one station that is far stronger than the rest. In this case
attenuating all of the signals with a simple attenuator will cause the desired stations to be weak
(snowy). In this case you must reduce the strength of only the offending station. A common FM
trap will help if the problem is a nearby FM tower. If the problem is a nearby TV station, often the
station management can provide suitable filters.
… You may have chosen the incorrect cable standard. Not
all televisions can accommodate the 1.25MHz frequency difference between the H and I cable
standards.
Infrared Remote Control Problems … Use the red
light on the side of the modulator
section as a trouble shooting aid. This light will blink as remote control signals are relayed.
If the light seems to indicate proper operation, but the component is not being controlled,
the IR emitter may be mis-located. Be sure the emitters are in front of the IR sensor.
IR DATA
If the light is on constantly, one or more IR targets is receiving electrical or optical noise. At the
modulator section unit, begin to disconnect the outputs to the TVs until the
goes off.
This will tell you which IR target is the source of the noise.
Next cover the front of the offending IR target. If the
light turns off, the IR target is
‘seeing’ a source of IR noise, such as a solid state flourescent lamp. If the light does not go out,
the problem may be radiated electrical noise from the TV. Reposition this IR target. If
repositioning the IR target does not help, the TV may be conducting noise from its input. Place a
DC block between the IR target and the TV.
IR DATA
Simple DC-block for RF Inexpensive 0-20dB attenuator
CH
C
CH
D
VIDEO AUDIO L AUDIO R
CH
A
CH
B
VIDEO AUDIO L AUDIO R
OUTPUT
600mA 15VDC POWER
Model 3445
Sample System Diagram
SATELLITE
RECEIVER
VCR
DVD
VCR
12:00
Video/audio
outputs
Video/audio
outputs
Video/audio
outputs
CCTV Camera
at front door
CATV/Antenna
In this system, CATV or antenna
channels are available on all TVs. In
addition the following channels have
been added:
Channel 66 - Front door channel
Channel 68 - VCR
Channel 70 - Satellite receiver
Channel 72 - DVD player
RG6 coax
preferred
RF section
(Distributes to as many as 8 TVs)
3
To more TVs
Any or all TVs may have
a model 2133 IR Target
Control the DVD,
DSS or VCR from
any room.
Model 2173 IR emitter repeats
what the IR target ‘sees’ in the
other room.
Use
only
shielded
75
ohm
coax
Attach the IR emitter directly
over the IR sensor.
Remove jumper for Hi-Z (See manual)
A B C D