NetMedia MicroModulator MM70 Troubleshooting Tips

There are many variables involved in Video Distribution. Cable lengths, splitter/combiners, and pre-existing signals can all impact picture
quality. In general, good results are achieved when the field strengths (dB) of each signal are balanced throughout the system. Combinations of
amplifiers, attenuators, and tilt compensators may be necessary to ensure an equalized and sufficient delivery of signal to each television. You
may wish to consult your local A/V Professional whose tools and expertise can help provide you with optimal results.
Modulator
Channels 0-13 Not valid channel selection.
Channels 14-69 UHF Stations 14-69
Channels 70-94 CABLE Stations 70-94
Channels 95-99 Not valid channel selections.
Channels 100-125 CABLE Stations 100-125
Channels 80-116 Can conflict with DIGITAL CABLE, use 120-125
This table covers all NetMedia Modulators, MM70, RM70, and MM73. Also see their individual tables for more help.
Symptom
No picture on programmed 1. TV must be set to ANTENNA Tuning in order
UHF channel 14-69 to view UHF channels 14-69.
No picture on programmed 2. TV must be set to CABLE Tuning in order to
CABLE channel 70-94, view CABLE channels 70-94, 100-125.
100-125
No picture through Cable 3. Cable Boxes normally use CABLE Tuning.
Box.
4. Cable Boxes sometimes put the modulator
signal on a different channel or do not pass the
signal at all.
5. If you cannot get a signal through the Cable
Box then you must bypass it and switch the TV
between channel 3 and the modulator channel.
No picture on programmed 6. The modulator does not program channels
CABLE channel 95-99. 95-99.
Modulator has "forgotten" 7. The channel is stored in EEPROM and is not
programmed channel. forgotten, though a bad power glitch may
occasionally scramble the signal.
Bad signal on station next 8. Modulated channels will interfere with
to programmed channel. adjacent channels, esp. the one just below it.
"Noise" on programmed 9. Local UHF broadcast channels can interfere
CABLE channel 70-94, with CABLE channels.
100-125.
Weak, "snowy" signal on 10. Signals must be balanced before combining.
Cable, Antenna, or Cable and Antenna signals are generally not as
modulator channels after strong as the modulator's. Also, the additional
signals combined. cable and combiners disperse and weaken their
signal strength.
Horizontal, diagonal, or 11. Signal may be too strong for television.
herringbone lines on any Modulator output is at least +27dB.
distributed channel.
12. Combined signals are unbalanced.
Modulator Troubleshooting 103003.doc
Troubleshooting Tips
Modulator Channels
Channel range for MM70, RM70, and MM73 Modulator function.
Description
All Modulators
Description
NetMedia, Inc. 10940 N. Stallard Place, Tucson, Arizona 85737 (520) 544-4567 Fax: (520) 544-0800
mailto: sales@netmedia.com http://www.netmedia.com
Copyright © 2000 - 2003 NetMedia Inc. All Rights Reserved
No signal should appear on TV.
Set TV to ANTENNA Tuning for its UHF channels 14-69.
Set TV to CABLE Tuning for its CABLE channels 70-94.
No signal should appear on TV.
Set TV to CABLE Tuning for its CABLE channels 100-125.
Set TV to CABLE Tuning for its CABLE channels 120-125 and bypass the cable box.
Recommended Action
1. Tune TV to channel 80. If successful, your TV is probably in CABLE Tuning mode
Check the switches or menus on your television and change from CABLE Tuning to
ANTENNA Tuning.
Leave the TV in CABLE Tuning and program the modulator for a CABLE channel from
70-94, 100-125.
2. Tune TV to channel 80. If not successful, your TV is probably in ANTENNA Tuning mode
Check the switches or menus on your television and change from ANTENNA Tuning to
CABLE Tuning.
Leave the TV in ANTENNA Tuning and program the modulator for a UHF channel from
14-69.
3. Program the modulator for a CABLE channel from 70-94, 100-125.
4. Check for the modulator signal several channels above and below the programmed
channel.
5. Combine the modulator signal to the cable signal after the Cable Box.
Split the combined cable/modulator signal before the Cable Box and recombine again after
the Cable Box. Use a filter or trap to eliminate channel 3 on the bypassed side.
Use an A/B Switch to select between modulated and cable signal.
6. Program the modulator for a CABLE channel from 70-94, 100-125.
7. Disconnect modulator power supply and reconnect after waiting for several seconds.
Programmed channel should reappear.
8. Program channels with at least one blank channel above and below.
9. Program the modulator for a CABLE channel 70-94, 100-125 that is not close to a local
UHF broadcast channel frequency (UHF 14 to 43 add 51; UHF 44 to 69 add 56.
Examples: UHF 43 is close to CABLE 94; UHF 44 is close to CABLE 100).
10. Amplify weaker "snowy" signal before combining with others to boost strength and help
signal balance. Use other combinations of amplifiers, attenuators, and tilt compensators to
provide a balanced and sufficient signal to each television.
11. Weaken signal with gain controls, attenuators, splitter/combiners, or longer cable
lengths.
12. See Step 10.
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