modulator will be assigned to and keep any potential interference
out of the system. Model 3102, cleans up channel 80 and above.
7. Allow 1 to 2 channel spacing between modulated channels and
"active" channels.
8. Always compensate for insertion loss with splitters and taps.
There will always be a drop in antenna/cable signal strength when
combining a modulator to an existing system (because of insertion
loss with the combiner).
9. When combining an existing signal with a modulated signal, make
sure to have equal signal strength at the point of the combiner so
one signal does not degrade the other and cause beat frequencies.
10. When possible, use the lowest frequencies available for the
modulated channels. Lower channels (frequencies) have lower
signal loss on the cable runs.
11. When in doubt, run the signal a little high to the television and use
an attenuator to lower the signal strength going into the TV.
Attenuators may be combined (i.e. two -3dB attenuators. will
equal -6dB).
12. Make sure to use a well shielded coax of either RG6, RG6 Quad
or RG11 for long feeder drops.
13. Use RG59U Coax for composite/baseband video signals only.
14. Combine the modulator into the video distribution system as far
"up-stream" as possible.
15. If the system needs to be amplified use the amplifier as far "up-
stream" as possible.
Trouble Shooting
Trouble shooting any system can make or break the entire installation.
Here are the most common problems and solutions. After trying
these solutions, call 800/840-0288 for 24 hour technical
assistance. Calls before 8am and after 5pm pacific standard time
will be returned by the technician on call.
Stops Modulating : No Modulation
Modulator requires proper ventilation for long life reliability and
continued operation. Unplug unit, let it cool down, install in well
ventilated area to continue operation.
Snowy Picture : No Modulation
This is a problem of the TV and the modulator not "talking" to each
other.
1. Verify the modulator is set up for the proper TV channel band. If
cable TV or antenna? If the unit uses dip switches to set the
channel band, was the unit powered down during or after the
switches were reset to the proper band? If the unit uses a jumper
check for proper placement.
2. Verify the TV is set up on the proper TV channel band. Use
"Air" for UHF channels or Cable for Ultraband channels . The
TV will have an on screen set-up menu or a switch for this
function. Also make sure the modulated channel isn't blocked out
by auto-programming. To check for the TV being set to the
wrong band, go to the equivalent channel on the other band (i.e.
to check 65 cable try 14 UHF). Add 51 channels for antenna
connection to cable channels.
3. Check TV manual to make sure TV works on channel above 65.
4. Check all connections for a good connection.
5. Check splitters and amplifiers for 1GHz rating.
6. Try another TV, bypass all components and go directly into TV.
Black Picture : No Modulation
In this case, the TV and the modulator are "talking" to each other. The
video signal is not being passed through the system.
1. Verify good connections to the modulator from the video source.
i.e. VCR.
2. Check video source (VCR, Sat Receiver etc.) by running the
outputs directly into the video inputs on the TV. Verify video
source is working.
3. Check for power at video source.
4. Disconnect modulator from system:
A) Picture goes to snow, problem is between video source and
inputs on the modulator.
B) Picture stays black, hook up the modulator
directly to a TV eliminating all the components of the system and
check the picture.
Grainy Local Channels : Good Modulated Picture
1. Disconnect the modulator from the system and connect the local
channel feed directly to the distribution system and check TV picture
quality.
A) If the picture quality is good the insertion loss of the
combiner for the modulator is degrading the local channel
signal. Use a CVT-15PIA to compensate for the insertion loss.
B) The other alternative is to use a 6dB tap as the combiner, put
the local channel feed on the pass through port for a minimal
loss of signal connect the modulator to the tap off port.
C) If the picture is still bad, check for a bad connection where
leakage may occur or if the shielding braid is touching the
center conductor.
2. Install model CVT-15PIA amplifier on the incoming cable
before the combiner. See basic schematic.
Grainy Modulated Channel : Good Picture on the Cable Channels
1. Disconnect cable channels from the system and check the
modulated channels.
A) If the modulated channels are good, use a low pass filter to
"clean-up" the incoming frequencies to be modulated.
B) If the modulated channel does not improve after
disconnecting the local channels, evaluate signal loss of
modulator through the splitters and cable length of the
system. Amplify after the combiner if needed.
C) Also check the connections between modulator and the
combiner for leakage or the cable braid is touching the center
conductor.
2. Check output strength with field strength meter.
3. Connect modulator directly to TV and check picture quality.
4. Check bandwidth of all splitters and amplifiers for 1GHz
capability.
5. Place TV cable setting on standard, NOT HRC or IRC.
TV Won't Tune High Enough to get Modulated Channel
1. Use an external tuner i.e. VCR or a Cable Box converter tuner
(Channel Vision Model #1172) to allow the TV to view a
modulated channel on channel through the external tuner..
2. If the modulated channel is beyond the capabilities for that TV,
the TV will not work with the system.
Cable Company Box Won't Pass a Modulated Signal
1. Connect modulator directly to TV and verify the modulator is
sending a signal the TV can receive.
2. Use model 3101 Cable Box Combiner Kit to route the modulated
signal around the cable box. See schematic page..
Cable Company Uses All Available Channels
1. Use a low pass filter (3102) to block out channels 80 and above
for clean modulation (won't effect channels 95-99).
2. Call for pricing on a custom filter to block out a specific channel
or multiple channels.
Modulated Picture is Too Bright or Washed Out
1. Slide impedance switch to 75
Ω
position.
2. If modulator is a E Series set top style, adjust video level
adjustment potentiometer on the bottom of the chassis.
3. If using a camera, check positioning of the lens to be sure it's not
