This issue has been previously discussed in the following thread: All channels except StarzHD 261 and 262. That thread has grown too big. I decided to start a new one and provide a quick summary of the problem. Hope, this will be helpful.
Symptoms
Some people are getting BravoHD+ (edit: now UHD) instead of StarzHD on channel 261, or have some other channels mixed up (e.g., 204, 206, 226, 229, 261, 262, 301, and 305). The problem may be limited to a single STB, or it may be present on all STBs in the house.
What's going on?
Most channels on VOOM use "Right_Ve" polarity. StarzHD and other channels listed above are exceptions. They use "Left_Horiz" polarity. The polarity is switched within the LNB. To change the polarity from "Right_Ve" to "Left_Horiz", the STB sends a signal to the LNB: it increases the voltage from 13 Volts to 18 Volts. VOOM uses dual-LNB with two separate coax connectors, allowing two STBs switch polarity independently from each other. If you have more than two STBs, the polarity switching is done within a special multi-switch. In any case, the correct voltage must be passed from the STB to the LNB (or to the multi-switch). If the proper voltage is not passed (due to voltage loss in cables, connectors, diplexers, etc., or due to incorrect wiring) the wrong channel might be displayed. Here are some possible causes of the problem:
Voltage loss
To switch polarity, the STB sends 18 Volts to the LNB. Long cable run, old wiring, poor connections, improper or defective diplexers - all cause excessive voltage loss. If the voltage loss through cable run is more than 2.5-3 Volts, the polarity switch may not occur. (Example: a good 300' RG-6U cable looses more than 3.5 Volts!)
Bad or improper diplexer
Diplexers must pass voltage not only to the LNB, but also to the power-amplified OTA antenna. If you have multiple STBs, each of them should pass voltage to the LNB (or to the multi-switch), but only one of them should pass voltage to the antenna. If the voltage is not passed correctly, or if the diplexers allow voltage to be passes from one STB to another, the polarity switching will not work properly.
Incorrect wiring
A typical mistake would be using a 2- or 3-way splitter for OTA antenna that passes voltage in all directions. This cannot be used with diplexers that pass voltage too. This may result in voltage being passed from one STB to another via the splitter. Another mistake is using a splitter for a satellite cable. If the satellite cable is split, your STBs will not be able to switch polarity independently from each other.
Power inserters
Power inserters should not be used with diplexers! A power inserter provides fixed voltage to both the antenna and the LNB, effectively preventing any polarity switching. However, you can use power inserters for OTA if you have a separate cable run to your antenna.
Bad multi-switch
A defective multi-switch may get "stuck" on one polarity regardless of the voltage supplied.
Bad or improperly installed LNB
A defective LNB may get "stuck" on one polarity regardless of the voltage supplied. Also an improperly installed (incorrectly oriented) LNB may be causing this problem too.
Case study
Here is the list of some posts and comments about what was done to resolve the "Channel Mix-up" problem:
So, what should you do if you have this problem?
Call VOOM and request a service. Tell them that you suspect a problem with wiring or with your LNB. (Do not request a new STB - this won't help!) Talk to the installer and tell him that you are having a problem with polarity switching in the LNB. Most installers know what polarity problems are and how to troubleshoot them, but if you only tell them that you are getting wrong channels, they may not realize that this is a polarity issue.
If you are experienced enough and feel like troubleshooting it yourself, you can switch the STB to channel 261 and check voltage with a voltmeter at the LNB, or at any other connection point. It should be above 15.5-16 Volts for channels with "Left_Horiz" polarity.
Good luck!
Symptoms
Some people are getting BravoHD+ (edit: now UHD) instead of StarzHD on channel 261, or have some other channels mixed up (e.g., 204, 206, 226, 229, 261, 262, 301, and 305). The problem may be limited to a single STB, or it may be present on all STBs in the house.
What's going on?
Most channels on VOOM use "Right_Ve" polarity. StarzHD and other channels listed above are exceptions. They use "Left_Horiz" polarity. The polarity is switched within the LNB. To change the polarity from "Right_Ve" to "Left_Horiz", the STB sends a signal to the LNB: it increases the voltage from 13 Volts to 18 Volts. VOOM uses dual-LNB with two separate coax connectors, allowing two STBs switch polarity independently from each other. If you have more than two STBs, the polarity switching is done within a special multi-switch. In any case, the correct voltage must be passed from the STB to the LNB (or to the multi-switch). If the proper voltage is not passed (due to voltage loss in cables, connectors, diplexers, etc., or due to incorrect wiring) the wrong channel might be displayed. Here are some possible causes of the problem:
Voltage loss
To switch polarity, the STB sends 18 Volts to the LNB. Long cable run, old wiring, poor connections, improper or defective diplexers - all cause excessive voltage loss. If the voltage loss through cable run is more than 2.5-3 Volts, the polarity switch may not occur. (Example: a good 300' RG-6U cable looses more than 3.5 Volts!)
Bad or improper diplexer
Diplexers must pass voltage not only to the LNB, but also to the power-amplified OTA antenna. If you have multiple STBs, each of them should pass voltage to the LNB (or to the multi-switch), but only one of them should pass voltage to the antenna. If the voltage is not passed correctly, or if the diplexers allow voltage to be passes from one STB to another, the polarity switching will not work properly.
Incorrect wiring
A typical mistake would be using a 2- or 3-way splitter for OTA antenna that passes voltage in all directions. This cannot be used with diplexers that pass voltage too. This may result in voltage being passed from one STB to another via the splitter. Another mistake is using a splitter for a satellite cable. If the satellite cable is split, your STBs will not be able to switch polarity independently from each other.
Power inserters
Power inserters should not be used with diplexers! A power inserter provides fixed voltage to both the antenna and the LNB, effectively preventing any polarity switching. However, you can use power inserters for OTA if you have a separate cable run to your antenna.
Bad multi-switch
A defective multi-switch may get "stuck" on one polarity regardless of the voltage supplied.
Bad or improperly installed LNB
A defective LNB may get "stuck" on one polarity regardless of the voltage supplied. Also an improperly installed (incorrectly oriented) LNB may be causing this problem too.
Case study
Here is the list of some posts and comments about what was done to resolve the "Channel Mix-up" problem:
wbuffetta - replaced flat cable with a standard coax cable
Videofx - replaced the diplexer (wrong diplexer type)
StewartFan - repointed the dish
Dawson9 - reinstalled the antenna to a separate pole (???)
mkwillia - replaced (removed?) the diplexer
andrzej - replaced the LNB
pederb - removed a splitter dividing the signal to MyHD card
vurbano - reproduced the problem using Channel Master diplexers
jimmykce1 - replaced old (powered) diplexer with the correct one
telekol - removed power injector (Do not use power injectors if you have a 1 wire install with diplexers)
txdude - Winegard diplexer allowed voltage from the STB to travel back to the other STBs that are connected to diplexer. The simple fix was the installation of a 35-DTV34MINI Digital Multi-Switch.
mike528 - Replaced 18" dish with a 24" dish
Videofx - replaced the diplexer (wrong diplexer type)
StewartFan - repointed the dish
Dawson9 - reinstalled the antenna to a separate pole (???)
mkwillia - replaced (removed?) the diplexer
andrzej - replaced the LNB
pederb - removed a splitter dividing the signal to MyHD card
vurbano - reproduced the problem using Channel Master diplexers
jimmykce1 - replaced old (powered) diplexer with the correct one
telekol - removed power injector (Do not use power injectors if you have a 1 wire install with diplexers)
txdude - Winegard diplexer allowed voltage from the STB to travel back to the other STBs that are connected to diplexer. The simple fix was the installation of a 35-DTV34MINI Digital Multi-Switch.
mike528 - Replaced 18" dish with a 24" dish
So, what should you do if you have this problem?
Call VOOM and request a service. Tell them that you suspect a problem with wiring or with your LNB. (Do not request a new STB - this won't help!) Talk to the installer and tell him that you are having a problem with polarity switching in the LNB. Most installers know what polarity problems are and how to troubleshoot them, but if you only tell them that you are getting wrong channels, they may not realize that this is a polarity issue.
If you are experienced enough and feel like troubleshooting it yourself, you can switch the STB to channel 261 and check voltage with a voltmeter at the LNB, or at any other connection point. It should be above 15.5-16 Volts for channels with "Left_Horiz" polarity.
Good luck!
