Snowy Picture : No Modulation
This is a problem of the TV and the modulator not “talking” to
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.
hitam tapi bukan Modulasi
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.
2. Check video source (VCR, Sat Receiver etc.) by running the outputs
directly into the video inputs on the TV. Verify video source is
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.
gambar yang berasal dari local TV
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 an amplifier 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.
bintik-bintik seperti percikan air
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
6. Place TV cable setting on standard, NOT HRC or IRC.
Won’t Tune High Enough to get Modulated Channel
1. Use an external tuner i.e. VCR or a Cable Box converter with high
enough range toreach the modulated channel, 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.
Gambar putih remang
1. Slide impedance switch to 75 ohm position
2. If modulator is a CTDM 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.
1. If baseband video is being split, you may require a video
2. If modulator is a CTBM 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.
1. Insert grounding block in line and ground coax cable before it
enters the TV.
2. Use professional grade audio/video interconnect between the
components and the modulator.
Suara sangat lemah:
Use a Y-Connector to combine the left and right audio before entering
Muncul gambar bergaris
Disconnect modulator from local channels an check modulated
channel. If there is programming move the modulated channel. If the
picture is snowy, use a low pass filter to block noise or data coming
in from cable
Horizontal bayangan melebar
1. Check for a component of the system that is introducing DC power
into the system. Disconnect that component and check TV. If the hum
bars stop, use a DC blocker down stream from that component to block
the power from getting to the TVs
2. If the rolling is only on the modulated channels, check for
impedance mismatch by adjusting the video level adjustment pot.
Vertical bayangan melebar
Check for AC power getting on the line. Use a ground breaker in line.
hitam putih berjalan
Move modulated channel up to a new channel. If problem persists and
all of the inputs of a multiple input modulator are not being used,
check default channels on modulator to see if default channel is set
to the same channel that the problem channel is.
Flashing at the Top or Middle of TV Picture
1. If flashing is on modulated channels, turn up attenuator/down gain
2. If flashing is on local channels turn down gain or attenuate output
Picture is Tearing
Possible impedance problem. Check that impedance switch is set to 75
Bayangan dalam gambar
1. Check for low quality combiner in system. Replace with high
isolation combiner, HS model combiner.
2. Check the type of coax used in system. Inadequate shielding in coax
will cause ghosting. Pull new coax (RG6 quad).
3. It could be Halloween
Low Channel Pictures are
Good, High Channel Picture is Grainy
1. Place a tilt compensator in line after the amplifier and
increase amplifier gain until the higher channels look good.
2. Check frequency specs on all splitters and amplifiers in system.
Replace any that are not broadband 5MHz to 1GHz.
Channels Have Vertical Lines, High Channels are Good
1. Cabut kabel modulator dari tegangan AC
a) Lihat Channels jika hasilnya clear: problem is beat frequencies or
unbalanced cable vs. modulator
1. Decrease modulator power by adjusting attenuator (red knob on back)
or use external attenuators before it is combined with the cable TV
2. Use a 9 or 12dBmV tap in reverse instead of the supplied combiner.
3. Install a 5 or 10dBmV tilt compensator to reduce low channel power
4. Amplify cable TV before you combine modulated signal to balance.
5. Use a high pass filter on the output of the modulator.
b) Low Channels are still bad : bad component in system.
1. Check signal at source without splitters, amplifiers etc. in the
2. Read system installation checklist.
3. Trace picture from beginning to end. Use process of elimination.
c) Picture still has wavy lines at the source Call for cable company
service. They have a bad component in their system. Garbage in equals
not Receiving all Channels Being Distributed
1. Cek kabel coaxial jika RG59 ganti dengan RG6
2. Cek semua splitters dan amplifiers for broadband specifications
3. Check TV specifications for available channels.