6
Things to watch for:
Nopicture
Weak ChannelPlus UHF channel
Audiovolume is low
… Verifythat 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
broadcastingon UHF channel 16, make sure the TV is on UHF 16 rather than CATV 16. UHF 16
andCATV16 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
audiolevel, both right and left inputs must be used. If you have a mono source, connect it to both
rightand left inputs using an RCA ‘Y’ connector.
Seethe section on programming.
lightIRDATA
IRDATA
LEDsblink
Herringbone interference on ChannelPlus channel (diagonal lines)
Herringbone interference on many channels, including ChannelPlus
channels (disappears when you remove the CATV/Antfeed)
Nocolor on ChannelPlus channels
...You need to have one unused channel space between channels. The display will
blinkif you have made an ‘illegal’ choice. Seethe section on programming.
...
Youmayhave 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
movingthe ChannelPlus channel to another number. Youmayhave to add a low pass filter to
removecable company noise. Ifa filter does not work, try adding a DC-block to remove common
modeinterference.
… 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
attenuatingall of the signals with a simple attenuator will cause the desired stations to be weak
(snowy). Inthis case you must reduce the strength of only the offending station. A common FM
trapwill help if the problem is a nearby FM tower. If the problem is a nearby TV station, often the
stationmanagement can provide suitable filters.
…Youmay have chosen the incorrect cable standard. Not
alltelevisions can accommodate the 1.25MHz frequency difference between the H and I cable
standards.
InfraredRemote Control Problems … Use the red lighton the side of the modulator
sectionas a trouble shootingaid. Thislight will blink as remote control signals are relayed.
Ifthe lightseemstoindicate proper operation, but the component is not being controlled,
theIR emitter may be mis-located. Be sure the emitters are in front of the IR sensor.
IRDATA
Ifthe light is on constantly, one or more IR targets is receiving electrical or optical noise. At the
modulatorsection unit, begin to disconnect the outputs to the TVs until the goesoff.
Thiswill tell you which IR target is the source of the noise.
Next cover the front of the offending IR target. Ifthe 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
repositioningthe IR target does not help, the TV may be conducting noise from its input. Place a
DCblock between the IR target and the TV.
IR DATA
SimpleDC-block for RF Inexpensive0-20dB attenuator
CHC CH D
VIDEO AUDIOL AUDIOR
CHA CH B
VIDEO AUDIOL AUDIOR
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
CCTVCamera
atfront door
CATV/Antenna
In this system, CATV or antenna
channels are available on all TVs. In
additionthe following channels have
beenadded:
Channel66 - Front door channel
Channel68 - VCR
Channel70 - Satellite receiver
Channel72 - DVD player
RG6coax
preferred
RFsection
(Distributesto as many as 8TVs)
3
Tomore TVs
Anyor all TVs may have
amodel 2133 IR Target
Controlthe DVD,
DSSor VCR from
anyroom.
Model2173 IR emitter repeats
whatthe IR target ‘sees’ in the
otherroom.
Useonly shielded 75 ohm coax
Attachthe IR emitter directly
overthe IR sensor.
RemovejumperforHi-Z
(Seemanual)
ABCD