[dfwguy81]

Hey all -

Having a strange issue. When we are watching tv sometimes it will just switch to the Directv Cinema commercial channel. The channel doesn't actually switch on the receive but we are just all of a sudden viewing the cinema channel. If you press info it still appears that you are watching the channel you are watching.

If you try and change the channel it just goes black and you have to power off and on to get back to the correct channel.

It happens maybe once day. There really seems to be no rhyme or reason. Sometimes it isn't the cinema channel but another channel that fades in - I just can't tell which channel it is.

We also get a 771a error once in a while. When that happens sometimes cycling power will work - most of the time it will require a reset.

A tech has been out twice but nothing has fixed it. When it happens all of our sattelite strength readings go to 0.

All of the connections are tight - just trying to see if I can troubleshoot myself and replace whatever is causing this to happen.

Thanks!

 

[Davenlr]

Power supply in the receiver, bad coax, or a bad LNB is causing your LNB to drift off frequency. A service call is in order.

 

[dfwguy81]

Thanks!

 

[Floyd]

To help narrow down the cause of your problem it would help if we knew your setup....multiswitch or SWM? Are there any other receivers that you can use to substitute for the "changing" receiver? If you have a multiswitch you can bypass it. If there are any outdoor connections you can examine them to check for internal corrosion.

In my experience an LNB doesn't drift, but if the voltage/current supplied to it is not correct it can malfunction. If an LNB did drift in frequency it would not likely stop at a working channel frequency.

 

[veryoldschool]

In my experience an LNB doesn't drift, but if the voltage/current supplied to it is not correct it can malfunction. If an LNB did drift in frequency it would not likely stop at a working channel frequency.

Actually they have been known to do this. The LO drifts enough for the next channel to be received and the receiver doesn't know it.

This does explain the OP's problem pretty close.

 

[TigersFanJJ]

I've seen improperly installed connectors cause this issue also. Usually when the dialectric isn't flush with the base of the connector.

 

[veryoldschool]

I've seen improperly installed connectors cause this issue also. Usually when the dialectric isn't flush with the base of the connector.

I used an AIM on two LNBs today and one had an LO offset of less than 1 MHz, while the other was greater than 3 MHz.

 

[dfwguy81]

I'm thinking it is a coax issue.

I have a swm system with an 8 port splitter.

The fade seems to happen only on some channels like tnt or history... although it could actually be happening on others. It never happens in locals. It almost always takes you to the cinema preview channel. Only resetting the receiver will bring it back. If you try and change channels it just goes black. If you press info it still thinks is in the real channel still.

In addition to the fading I also get a 771a error frequently.

It only happens on the den receiver. I switched receivers today and it still did it even on the switched receiver.

I'm thinking it has to be the cable... I'm going to run fresh cable t the box and see.

 

[Floyd]

If the cable doesn't fix it try a new SWM-LNB, which might be sending the wrong frequency bands in on the SWM channels.

 

[veryoldschool]

If the cable doesn't fix it try a new SWM-LNB, which might be sending the wrong frequency bands in on the SWM channels.

That's why the AIM measures the offset of the LNB oscillator.