Channel Vision Frequently Asked Questions
- Channel Vision Catalog (Low Resolution) (3MB PDF)
- Channel Vision Catalog (High Resolution) (11MB PDF)
- 10 Common Problems
- Diagrams and Layouts
- RF System Upgrade
- IR Distribution (62KB PDF)
|10 Common Problems Associated with Modulation|
|Diagrams & Layouts|
Channel Vision Glossary of Terms: Page 1
Typical Residential RF System
Channel VisionTMRF System Upgrade
Diagram shows a typical residential audio/video system upgrade using a Channel Vision digital RF modulator. The modulator creates a distinct channel for each video source and is then combined with the antenna or cable signal for distribution throughout the home. Selecting any source from any television becomes as simple as changing the TV channel!
Channel Vision Trouble Shooting
Trouble shooting any system can make or break the entire installation. Here are the most common problems and solutions.
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 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 of 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).
3. Check TV manual to make sure TV works on channels above 65.
4. Check all connections for a good connection.
5. Check splitters and amplifiers for 1GHz rating.
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
Disconnect the modulator from the system and connect the local channel feed directly to the distribution system and check TV picture quality. 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. The other alternative is to use a 9dB 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. 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.
Grainy Modulated Channel : Good Picture on the Cable Channels
1. Disconnect cable channels from the system and check the modulated channels. If the modulated channels are good, use a low pass filter to "clean-up" the incoming frequencies to be modulated. 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. Also check the connections between modulator and the combiner for leakage or braid touching the center conductor.
2. Make sure the attenuator is turned to 0.
3. Check output strength with field strength meter.
4. Connect modulator directly to TV and check picture quality.
5. Check band width of all splitters and amplifiers for 1GHz capability.
6. 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 turner (#1172) to allow the TV to view modulated channel on channel 3 or 4.
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 pages 4 & 5.
Cable Company Uses All Available Channels
1. Use a low pass filter (3102) to blockout channels 80 and above for clean modulation (won't effect channels 95-99).
Modulated Picture is Too Bright or Washed Out
1. Slide impedance switch to 75 ohm position
2. If modulator is a CVT 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 aimed at the sun or a reflection.
4. Adjust camera lens - see lens manual.
Modulated Picture is Too Dark
1. If baseband video is being split with a Stereo Loop Kit or loop through quad, set impedance matching switch (termination switch) to 1KW.
2. If modulator is a set top style, adjust video level adjustment potentiometer on the bottom of the chassis
3. If the video source is not being split, check input source directly into a TV
4. Adjust the video level adjustment pot on the chassis of the set top units to the proper brightness.
5. Check all connectors for 75 ohm.
Unavailable/discontinued items are listed below for your reference.