4dtv sound dropouts

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waylew

SatelliteGuys Pro
Aug 23, 2010
2,703
1,064
northern WEST new york
thanks sergei,
I have used the 6778 to originally set the thing up. I do now know if i have a 6d or not, I do believe the poloroter is working properly now. I have unhook the polorotor after putting on the TCM channel and it still pops off at 40 seconds. My other stations seem to work normally except occasionally the picture will freeze and sound continues. I just change stations and return and picture will be normal. I have removed the vcII.
It's time to figure out whether you have a 920 or 922.
Press OPTIONS 6 5 ,on line H what is the Current Version?This is the firmware on your receiver,depending on what you see there,that will tell us if you have a 920 or 922.
*
Now press OPTIONS 6 0 5 ,right arrow to Diagnostics C,what is the first number on the second line down,this is your lnb frequency offset (mine,for example,is 0.000,which is perfect).Also what the last number on line 3?Mine is +13.0.I'm using a 922 by the way.
 

sergei

SatelliteGuys Pro
Aug 29, 2007
1,266
5
iowa
thanks sergei,
I have used the 6778 to originally set the thing up. I do now know if i have a 6d or not, I do believe the poloroter is working properly now. I have unhook the polorotor after putting on the TCM channel and it still pops off at 40 seconds. My other stations seem to work normally except occasionally the picture will freeze and sound continues. I just change stations and return and picture will be normal. I have removed the vcII.

I still thing you either have a bad servo motor or it could even be the LNB itself also attached to the feedhorn is having the problems. Every time you change channel the servo motor will try an adjust to the new position. If you don't have a cover on it something might have even made a nest in it. You haven't said whether its a single C-Band or also has the KU with it. If all your using it for is the H2H ( Comcast ) programming then I'd just buy a LNBF for around 26 dollars and eliminate that as being the problem.
Trying to repair what you have just isn't worth the money, you'd spend 15 dollars on a servo and if that didn't fix it another 12 dollars plus for the LNB and you still have a moving part that has a history of going bad at the worse time. Plus the time to do it.
If you want to keep your 920 alive, don't turn it off, I've got 4 of them and they stay on 24/7 for my programming, and there attach to a Backup UPS.
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Line h is 6d, diag C is +1.125 and last number on 3 is +10.9.
I attached images in case i am looking wrong
Thanks
 

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sergei

SatelliteGuys Pro
Aug 29, 2007
1,266
5
iowa
In your second picture did you mess up the top two lines with ID and serial number so we couldn't read them?????

Sent from my Galaxy Nexus using SatelliteGuys
 

waylew

SatelliteGuys Pro
Aug 23, 2010
2,703
1,064
northern WEST new york
Line h is 6d, diag C is +1.125 and last number on 3 is +10.9.
I attached images in case i am looking wrong
Thanks
Okay,so you do have a 920.The pic shows +2.125,so the receiver is having to tune quite a bit off frequency,so that may be part of your problem.Usually like to see around 1.5 or less (the closer to zero the better) for that number.The +10.9 is good.
So you might want to consider replacing the LNB or even do away with the polarotor and go with one of the new pll LNBF's.Being a 920,ie old,it's also a good possibility one or more of the small electrolytic capacitors is starting to go.
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
yes i messed up the id, not for you guys but you never know who is looking at stuff and what they can do. Do you need to know them? i can send in private message.

can the tuning be changed or is that internal to the lnb. I do have a new lnbf and can put that in when the weather breaks. I have never put in a lnbf, anything different to watch out for? so when i put in the new lnbf that tuning number should go near zero?

Thanks all
 

waylew

SatelliteGuys Pro
Aug 23, 2010
2,703
1,064
northern WEST new york
Basically the oscillator in the lnb has drifted off (age?) so there's not a whole lot you can do other than replace it.
To install an LNBF on a 4DTV,press Options 6 4 2,line 2,LNB Type, set for C or C and Ku lnbf,line 4,Feedhorn Polarization, set for Rotated 90'.You should be able to just remove the polarotor from the scalar ring and slide the lnbf in it's place,you may have to do some minor filing or sanding to get the lnbf into the old scalar.Then it's just getting your skew set and a little peaking and your good to go.
The closer it gets to 0.0 the better,but 1.5 or less is acceptable .
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Thanks waylew, The scalar ring on my old lnb is larger then the new one. That was my first idea to just loosen the 3 set screws and slip the new on in. There is about half inch difference so i will have to change the ring also.
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Hi Waylew,
I just checked my diag C again after adjusting the position and now it is down to 1.25. Still have the drop outs. Would changing the position change the freq? or is this just a coincident. Also the day is a bit warmer today so that might have some barring on it. Will the freq change depending on what channel is on?
Thanks
 

waylew

SatelliteGuys Pro
Aug 23, 2010
2,703
1,064
northern WEST new york
Channel,satellite,polarity,really shouldn't much effect on it,but temperature certainly can.
And here's another thought,are you near an airport,ship port,weather radar or any thing else that might have a radar transmitter ?As I think about it your description of every 40 seconds and a horizontal transponder just screams radar interference.
I live less than a mile from the main shipping channel of the St Lawrence Seaway,and when a ship is passing by it will just swamp out any horizontal transponder and affect the vertical if it's close/strong enough.
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Hi Waylew, Thanks for the reply

I do not believe there is anything like that here unless it is top secret. Check out where i live. Go to map and look up happy camp, ca....lol you will see what i mean. But no telling what is going on here, i often hear humming in my ears that no one else hears and there may be some secret sub communication located here. We do have a small unmanned airport but no radar
 

sergei

SatelliteGuys Pro
Aug 29, 2007
1,266
5
iowa
yes i messed up the id, not for you guys but you never know who is looking at stuff and what they can do. Do you need to know them? i can send in private message.

I was concerned that maybe someone had messed with the unit like the guy in Chicago. You live in the middle of no where when looking at the map and I can't see any manufacturing that would cause problems and even radar I would thing would cause problem on mores than channel. And you are correct on the airport, it's VFR , no radar. But since it looks like your in a valley you may also have some type of relay system, radio or wireless which is sharing either the same frequency or nearby it. Have you checked with anyone else that has a dish in your area?
It'll be interesting to see if changing to the LNBF helps, at least it's warmer there than here in Iowa.
 
Last edited:

sergei

SatelliteGuys Pro
Aug 29, 2007
1,266
5
iowa
I have GI 4dtv receiver and have 10 channels from skylink.

Who is skylink, I can't find anyone under that name that offers 4DTV programming. Did you mean SkyVision?
 

waylew

SatelliteGuys Pro
Aug 23, 2010
2,703
1,064
northern WEST new york
Hi Waylew, Thanks for the reply

I do not believe there is anything like that here unless it is top secret. Check out where i live. Go to map and look up happy camp, ca....lol you will see what i mean. But no telling what is going on here, i often hear humming in my ears that no one else hears and there may be some secret sub communication located here. We do have a small unmanned airport but no radar
Oh well just a thought,you are in the middle of nowhere :D.Increasingly wishing I was in a lot less somewhere than where I am now.;)
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Thanks guys,

Yes I am in the middle of no where. But it is really quite beautiful here. I moved here 38 years ago and opened a tv repair shop. Closed it after divorce and been working for my ex mother in law in publishing company since. Now it is raining here, but it has been a pretty mild winter for us. Trouble is no snow pack so may have ruff summer with fires and all. If any of you are traveling west you are welcome to visit. Check out our publishing company. naturegraph.com We use to do all the production here including printing, binding, darkroom work etc.

Back to the subject. There are 3 tv translator that do not work well here, and the phone and police have repeaters on the mountain. As far as checking with other users, as far as I know I am the only one using the big dish now let alone 4dtv. This town is about 1000 at the post office and this is the biggest town for an hour and half drive.

It looks like it will be a while before I can put in the new lnbf, debating if I will change the one I have or put in another dish that is just sitting there. I am paranoid and like to have backups….lol
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Oh Yeah,
Sorry it was not skylink, it was Sky Vision, senility setting in. And oh yes i have read some stuff about the guy in chicago. I think that is who claims to do remapping and such. I saw some negative stuff and would be cautious about that.
 

Titanium

AI6US
Lifetime Supporter
May 23, 2013
7,344
8,433
Meadow Vista, Northern California
Would be easy to diagnose terrestrial RF interference with a spectrum analyzer connected to your LNB. It is just very unlikely that this is related to the downlink signal integrity or the LNB/feedhorn. If the signal was being interrupted by terrestrial interference or LNB/skew, the entire TS would be affected, not just the audio.

Remember that the entire mux from the transponder comes down as one fat stream of data. The receiver is instructed by the table (index) to separate and assign the data streams to compose the audio, video and other services that makes the individual channels. Any RF interference or momentary skew change would interrupt the data stream and not discreetly affect the audio on one channel in the mux.
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Thanks titanium, I do have a spectrum analyzer. I am not sure what to look for here. Here is a image. What do you think
spec-anlz.jpg
 

Titanium

AI6US
Lifetime Supporter
May 23, 2013
7,344
8,433
Meadow Vista, Northern California
Excellent! Nothing obvious when this capture was made...

Decrease the gain slightly to see the peaks 100% and wait for the dropout to occur. Did you see any spike or raised noise floor preceding the audio loss?
 

amvan123

Well-Known SatelliteGuys Member
Jan 24, 2014
26
0
CA
Update,
Several days ago I put in the new lnbf. Because of my paranoia I actually put in a second 10 foot dish. I installed the titanium c1-ppl. Now, so far my sound on tcm seems to be solved and also my picture freezing problem.
Thanks to all for all the help here, and I hope this may help someone else.
 
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