NetMedia MM70, MM73, RM70 Troubleshooting Manual

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

Channel range for MM70, RM70, and MM73 Modulator function.

Modulator Description Television

Channels 0-13 Not valid channel selection. No signal should appear on TV.
Channels 14-69 UHF Stations 14-69 Set TV to ANTENNA Tuning for its UHF channels 14-69.
Channels 70-94 CABLE Stations 70-94 Set TV to CABLE Tuning for its CABLE channels 70-94.
Channels 95-99 Not valid channel selections. No signal should appear on TV.
Channels 100-125 CABLE Stations 100-125 Set TV to CABLE Tuning for its CABLE channels 100-125.
Channels 80-116 Can conflict with DIGITAL CABLE, use 120-125 Set TV to CABLE Tuning for its CABLE channels 120-125 and bypass the cable box.

All Modulators

This table covers all NetMedia Modulators, MM70, RM70, and MM73. Also see their individual tables for more help.

Symptom Description Recommended Action

No picture on programmed
UHF channel 14-69

No picture on programmed
CABLE channel 70-94,
100-125

No picture through Cable
Box.

No picture on programmed
CABLE channel 95-99.

Modulator has “forgotten”
programmed channel.

Bad signal on station next
to programmed channel.

“Noise” on programmed
CABLE channel 70-94,
100-125.
Weak, “snowy” signal on
Cable, Antenna, or
modulator channels after
signals combined.

Horizontal, diagonal, or
herringbone lines on any
distributed channel.

1. TV must be set to ANTENNA Tuning in order
to view UHF channels 14-69.

2. TV must be set to CABLE Tuning in order to
view CABLE channels 70-94, 100-125.

3. Cable Boxes normally use CABLE Tuning.

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.

6. The modulator does not program channels
95-99.

7. The channel is stored in EEPROM and is not
forgotten, though a bad power glitch may
occasionally scramble the signal.

8. Modulated channels will interfere with
adjacent channels, esp. the one just below it.

9. Local UHF broadcast channels can interfere
with CABLE channels.

10. Signals must be balanced before combining.
Cable and Antenna signals are generally not as
strong as the modulator’s. Also, the additional
cable and combiners disperse and weaken their
signal strength.

11. Signal may be too strong for television.
Modulator output is at least +27dB.

12. Combined signals are unbalanced.

NetMedia, Inc. 10940 N. Stallard Place, Tucson, Arizona 85737 [phone] Fax: [phone]

mailto: [e-mail] http://www.netmedia.com

Copyright © 2000 - 2003 NetMedia Inc. All Rights Reserved

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

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.

successful, your TV is probably in ANTENNA Tuning mode

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Modulator Troubleshooting 103003.doc Page 1 of 2 Rev 0310A

Troubleshooting Tips

This table covers the NetMedia MM70 MicroModulator. Also see the All Modulators table for more help.

Symptom Description Recommended Action

Modulator does not work. 1. The modulator requires 12V DC 100mA power

and good signal connections.

2. Rule out external factors such as cable,
amplifiers, splitters, and other devices.

3. The modulator must be repowered for channel
changes to take effect.

Modulator does not work. 1. The modulator requires 12V DC 100mA power

Problems with other
devices connected to
coax.
Problem with device
connected to RM70.

Modulator does not work. 1. The modulator requires 12V DC 300mA power

This table covers the NetMedia RM70 Remote Powered Single Modulator. Also see the All Modulators table for more help.

Symptom Description Recommended Action

and good signal connections.

2. Power Injector is directional; power cannot pass
through TV side.

3. Coax shielding may short circuit power by
touching center conductor.

4. Sufficient power must reach modulator location.
Each RM70 requires 12V DC, 100mA in addition to
power requirement of attached device.

5. Rule out external factors such as cable,
amplifiers, splitters, and other devices.

6. The modulator starts from zero each time you
enter programming mode.

7. Power Injector introduces 12V DC power to coax
cable.

8. The RM70 can supply 12V DC power to an
external device. There must be sufficient power for
both units.

This table covers the NetMedia MM73 TriplePlay™ Modulator. Also see the All Modulators table for more help.

Symptom Description Recommended Action

and good signal connections.

2. Rule out interference from TriplePlay’s other
channels by setting them to 0.

3. Rule out external factors such as cable,
amplifiers, splitters, and other devices.

4. The modulator starts from zero each time you
enter programming mode.

NetMedia, Inc. 10940 N. Stallard Place, Tucson, Arizona 85737 [phone] Fax: [phone]

MM70 MicroModulator

1. Disconnect and reconnect power supply. Make sure all other connections are secure.
Check for correct power supply.

2. Connect modulator to coax and coax directly to one TV. Set TV to channel 80, then
program modulator to channel 80 and look for the momentary test bars. If TV will not tune
to channel 80, see Step 2 of the All Modulators table.

3. Review programming steps. Program modulator for a simple channel such as
20 or 80. Disconnect and reconnect power supply.

RM70 Single Modulator

1. Disconnect and reconnect power supply. Modulator LED should then glow brightly
before returning to normal dim state. Make sure all other connections are secure. Check
for correct power supply.

2. Check Power Injector direction so that MOD Arrow goes toward modulator and TV
Arrow goes toward television.

3. Check all coax F-connectors and replace if necessary.

4. Long cable runs will diminish power, place Power Injector closer to modulator. Amplifiers
and some splitter/combiners do not pass DC power, replace them or move Power Injector
so that those devices are not between it and modulator. Multiple devices require more
power, use a larger power supply that gives each modulator and device enough power.

5. Connect modulator to coax, coax to Power Injector, and Power Injector directly to one
TV. Set TV to channel 70, then program modulator to channel 70 and look for the
momentary test bars. If TV will not tune to channel 70, see Step 2 of the All Modulators
table.

6. Review programming steps. Program modulator for a simple channel such as
20 (2 presses) or 70 (7 presses).

7. Place Power Injector so that no splitter/combiners are between it and the modulator.
or

Use DC Blockers to prevent power from entering other devices.

8. Make sure external device uses 12V DC power.

Use a power supply that delivers 12V DC, 100mA + DEVICEmA.

MM73 TriplePlay™ Modulator

1. Disconnect and reconnect power supply. All three modulator LED’s should turn on

momentarily before returning to normal single LED on state. Make sure all other
connections are secure. Check for correct power supply.

2. Select each of the other two modulator LED’s. Enter programming mode but do not

select any channels. Wait for LED to Quit flashing.

3. Connect modulator to coax and coax directly to one TV. Set TV to channel 80, then

program modulator to channel 80 and look for the momentary test bars. If TV will not tune
to channel 80, see Step 2 of the All Modulators table.

4. Review programming steps. Program modulator for a simple channel such as

20 (2 presses) or 80 (8 presses).

mailto:[e-mail] http://www.netmedia.com

Copyright 2000 - 2003 NetMedia Inc. All Rights Reserved

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Modulator Troubleshooting 103003.doc Page 2 of 2 Rev 0310A