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Discussion Starter · #1 ·
Last night my family was watching Madonna concert on HBO on DTC-100 receiver on FPTV. After watching this crap for 30 minutes I decided to go upstairs and watch some sports (RCA non-HDTV receiver). No such lack. As soon as I switched to ESPN (206), HBO (501) sound crapped out! When I switched receiver to HBO (or some other channels), the sound on DTC-100 reappeared! How channel on one receiver can affect performance of the another? Note that because they are on different floor, remote interference is out of the question.


I am apologise upfront if such question have already been answered on this forum, but it is quite hard to search for such item.


 

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I'm afraid that it may have just been incredibly bad timing. I'll bet you were using the digital audio out of the DTC.


I watched that great show last night and my audio cut out at about 30 min in too. I instantly switched over to analog (got 'em both hooked up to the amp) and got my sound back so as not to miss one bit of this exquisite concert. Sounded just as good too but it's more fun to see the Marantz lit up with it's own D/A converters.


Switched back about 10 mins later and noted that the digital feed was back. This totally does not surprise me with all the HBO 501/504 audio static going on. I just pop over to analog, problem solved (except for the 5.1 stuff).


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Ken B.
 

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Discussion Starter · #3 ·
Ken, thank you for an insight,

however it was not bad timing.

I repeated switching 10 times. It cannot be coincident,

one receiver definately affected the other!
 

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Discussion Starter · #5 ·
Kippjones, STBs are on different floors. I have regular infrared remotes, so penetration through floor is impossible.
 

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This sounds like a problem at the dish level - the dish does things involving the LNB based on which channels you tune to, so bad wiring or a bad LNB can cause two connections to interfere with each other in the way you described. I'm not an expert so I'm sure someone here can explain it better. The problem is more common when you have one of those 4-way splitter boxes on the dish, which is probably the case for HDTV. I'd doublecheck all your connections on the 4Xwhatever switch and cabling or maybe even try a replacement switch out there.
 

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Discussion Starter · #7 ·
Thank you, I tried and all connections looks fine.

This happened not all the time and with some channels only!

Should I replace 4-way splitter box?
 

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I have been having sound problems with DirectTV ever since they added Dolby Digital on 501/504. The sound breaks up on other channels sometimes also. I went into the setup on the DTV receiver and turned off Dolby Digital and the sound problems went away. Dolby Prologic really sounds great.

hehe!


I believe it is DTV, not my receiver.


Jerry
 

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Sounds to me like a LNB or multiswitch problem.


If you understand how LNB's work (at least the way I was told they work) it's very possible for a second reciever to screw with the other recievers.


Someone correct me if I'm wrong.

Let's start with the old single LNB dishes, there were two types of LNB's single and double, right. The one single LNB could only tune on station at a time. The way I understood it is that channels are grouped in pairs on a single frequency. They were out of sync or something. The job of the LNB was to tune that channel including the tune up/down required for the specific channel. For example 100 and 101 would share the same frequency with each out of phase either + or -. The LNB would have to tune up or down depending on the channel. The LNB can only tune either up or down to tune a specific channel.


This is why the Dual LNB was used, two or more boxes with one dual LNB. One LNB is tuned up, one is tuned down. No need to have the LNB switch. Therefore many recievers could work with this system.


With the Dual DualLNB's the setup is similar with LNB A and LNB B diplexed at either 18 or 22Khz (? going from memory).


So, one box should never mess with another box unless.... you have one box configured as a one single LNB setup. If this was the case you would have one box trying to tell the LNB to tune up/down as channels change. When the channels on both boxes tune the same direction (odd channels, or even as long as they match) I think things would work fine. (Not sure about that though)


I'd start at the boxes, check the settings. Then I'd replace the multiswitch, see if that fixes the problem. I'd be sure to check that the outputs from the LNBs are connected to the correct inputs on the multiswitch. The last resort would be to replace LNB A.
 

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Jeff D,


Someone told you an interesting but inaccurate story of LNBs: An LNB is a combination of a Low Noise Amplifier (LNA) with it's probe and broadband preamp and Block Down Converter which converts the C band (4 GHz) or Ku band (higher) or still higher frequency DSS satellite signals down into the area of 2 GHz L-band to be shipped down to your DSS receiver. The LNB had better not change anything it does in response to an attached receiver or the whole system will fail.


Regarding what is occurring in your system, in addition to suspecting a multi-switch problem it may be possible that the second receiver is generating an interfering signal that is propagating back up the coax and leaking through the signal splitter in the multi-switch box.


You might want to mention the make and model of the second receiver to see if anyone else has the same combination. At my place I left my old receiver on the single bird round dish and figured that I cut it over to the new dish sometime when I was bored - I haven't been that bored yet!
 

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I have seen this happen with a bad 4 way multiswitch. Swap it out and see what happen. In this customer's installation, it would pixellate the screen and cause sound drop outs every time he switched to a different channel on the multiswitch.


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STOP HDCP on DVI

Don O
 

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I've heard of this happening for the following reasons:


- Bad 4way switch

- Too long or lossy cable runs to switch

- Newly added box that misbehaves in some way (some have said there are weird incompatabilities with certain combinations of different box brands on the same 4-way).


If you didn't recently add (or damage?) any cable runs, swapping out the 4way seems like a good first step. Altho running new cables might be cheaper to start with?
 

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Akenyon thanks for the information!


If an LNB only moves high frequency singals lower, can you explain why if you have 2+ recievers you NEED a dual LNB and a single LNB only works on a single receiver setup?

What's the reason behind that?
 
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