Tried to connect Coax to PC, now no signal at TV

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NoelMac

16 posts

Geek

#52944 7-Dec-2009 21:04

Hi - hope someone can help this newbie...

I ran a new length of coax from a splitter box to a new tv at the other end of the living room, and felt pretty good when it worked first time. Then I upgraded to Win7 and finally got media centre talking to my Linksys extender, and felt pretty good about that too, With the benefit of that burst of confidence, I took the other coax cable out of the bedroom and into the study and changed the plug on it to connect it to the TV card in the PC - so as to access Freeview through the media centre. That was when it all started going wrong - as at now, I have;
- been unable to get any sort of sense from TV option in media centre (am guessing I probably need a different card, or to connect the STB to the card, but will leave that for another day)
- disconnected coax from the PC and reinstated in the bedroom
- Freeview STB menus on the living room and bedroom TVs, but no picture or sound, and menu for checking signal shows no signal
- Media centre music and photos etc still works fine

I'm wondering whether I have inadvertently introduced some sort of short and knocked something out between the dish and STBs, or whether I made a mistake in leaving the unterminated end of the coax out overnight - may have gotten wet :-(

I haven't tampered with the cable at the splitter, or at the dish, since everything was last working.

Hoping someone can point me in the right direction...

Thanks in advance.

Cheers,
Noel.

DravidDavid

1907 posts

Uber Geek

#281261 10-Dec-2009 18:00

Hi Noel!

I Have recently gone thought the Freeview motions, but still have limited knowledge in the area. I would like to throw some ideas into the wind anyway, maybe some will catch.

When you took the other coax cable out of the bedroom, into the study and changed the plug on it to connect it to the TV card in the PC, did you change any cables around on the splitter or switch off any STBs? I ask this because some splitters have all ports "Power-pass" and some have only 1 port "power-pass". If you switched off the other STBs and the TV card wasn't plugged into a power pass port, (or configured to allow power) there would be no power getting to the LNB at all. The fact that all of a sudden you are getting No signal suggests that the LNB is not getting any power.

If your splitter has all ports power-pass, the splitter should say on the front: "All ports powerpass". If you have re-enstated the bedroom STB, make sure it is set to power the LNB and try again.

If your splitter is a "signle port power-pass" splitter, switch all STB's off except for the STB near the splitter, ensure it is set to power the LNB and experiment in order to find the power-pass port and see if you get your signal back. (I marked mine with a vivid, just incase I had to change anything around.)

The advice I was given is to make sure that the STB likley to be on 24/7 is set as the STB to power the LNB. I've also herd that if you have all the STB's and TV-cards in the house powering the LNB, you can damage it, but I could never get a solid answer and I could be very wrong!

PS: When changing cables around looking for the power-pass port, make sure you switch the STB off before disconnecting the RG6 cable from the splitter. I think you can damage the LNB if you leave the power on and randomly connect and disconnect it from the power all the time.

I hope I've made sense! With this wall of text!

Cheers,
David

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NoelMac

16 posts

Geek

#281281 10-Dec-2009 19:58

Thanks David - that's very helpful.

The splitter is labelled 'all ports powerpass', so I suspect that I've inadvertently damaged the LNB. The power transform for the bedroom STB has stopped working, so I guess maybe there was some sort of surge that took out both ends...

I'll pick up a new LNB from somewhere in town and see how I go - looks like they are priced reasonably cheap....

Thanks for the asist - much appreciated...

Cheers,
Noel.

DravidDavid

1907 posts

Uber Geek

#281302 10-Dec-2009 21:09

It is unlikely that the LNB is getting no power at all. It is possible that the LNB has been damaged due to 2 or more STBs providing power to it, although some here may be more knowledgeable in that department. It could be that I am completely wrong.

Like you said, LNBs are reasonably cheap so its not a big deal to get a new one and try it. However, I suggest playing around with the current setup as you may have a perfectly good LNB on the dish.

Have you tried removing the splitter all together? You could have a bad splitter. Connect the dish straight to the STB and try and get the channels back that way. If you can't, maybe default the settings on the STB and re-tune each channel. Switch the STB out for the next and do the same.

If you can get more channels, introduce the splitter again and test each port.

I don't want to influence you to purchase stuff you don't need, Haha!

Good luck!
David

NoelMac

16 posts

Geek

#281398 11-Dec-2009 07:44

Hi David,

The splitter has worked reliably for a couple of years with two STBs, and it looks to be a relatively simple device so I'm picking that it's not the problem - but your suggestion makes sense; I'll take it out of the loop and see what happens. Previous tests using the STB signal strength meter have shown that it's not getting a signal at all, so I'm reasonably confident that the issue lies somewhere south of the STB...

The more I think about it, the more I think that the failure of the power pack is likely to be a related event - coincidence is a rarer beast than it seems, often...

I'll post and let you know the results after the weekend...

Cheers,
Noel.

Jaxson

7678 posts

Uber Geek

Trusted

#281419 11-Dec-2009 09:58

Yeah in all these situations the process is to remove everything, get it going with the bare minimum and then re-introduce elements one by one.

Cyril is the resident guru on all things signal and wiring related and he tells me that multiple units powering the lnb is usually ok because the splitter uses diode steering to only allow the highest voltage power supply to reach the lnb. The others are providing power but only one of them gets through the splitter to the lnb at any one time, despite all ports being power pass.

NoelMac

16 posts

Geek

#282457 14-Dec-2009 20:12

Well, that was a learning curve...

After 1 new splitter and 1 new LNB I finally pinned the problem down to...a faulty termination on the cable itself. I forgot that I changed the plug at some point... a bit embarassing, but at least it's all working now.

Actually - it was useful in that I finally found out how to terminate these things properly - I didn't understand that the wire braid connection was as important as it is. There's a couple of giood videos on WikiHow if anyone is interested.

Cheers,