Loop through connection problem between pvr andvTV

[Lucid]

Thanks again.

Do me a favour an use the THANKS buttons on all the posts you've found helpful. It's a very small price to pay - just a couple of seconds - no financial cost - to say a proper thank you for the time and professional advice you've received from a trade member.

 

[Longshanks]

Yes of course. I’m 62 now and increainly losing the plot.

 

[Lucid]

Yes of course. I’m 62 now and increainly losing the plot.

I'm 53 and have already lost the plot

 

[winston1]

[QUOTE="Longshanks, post: 4986001, member: 114296"

(Also strange that pvr still functions, but guess that’s got much better tuner, needs less signal?).[/QUOTE]
The front ends of TVs and PVRs are similar. One will certainly not be “much better”.

 

[Longshanks]

Hi again

Update. Coax connection was broken in the connection box in our lounge. Now repaired by aerial company. Have now tried attenuator to fix the tv pixelating issue. I rotate it until signal strength drops, but this makes no difference to signal quality. Probably due to older, budget tv not coping. (Signal not too strong for pvr and not exhibiting this problem when plugged directly into tv)

Thanks

 

[Lucid]

Glad you got to the bottom of the newer issue. The solution comes under the heading "Broken Coax Cable" as previously suggested (see post #12).

Your report of application of the attenuator is interesting and goes against the general trend with these things. I can think of a few situations that might cause this result, but honestly, this has probably reached the end of what can be diagnosed remotely working from the snippets of information you can provide. I would suggest it needs an experienced set of eyes and a TV signal meter on-site to look over the TV and what it is doing. Did you ask the aerial guys to check the signal level getting to the TV?

You could still try moving the TV to another point in the house where there's a known good signal being displayed on a TV. This would show you whether the issue is specific just to that set. I would also doublecheck the tuning by doing a manual tune of the mux channel for either of the SD muxes for PSB1-BBC A, the main BBC channels in SD or PSB2-D3&4 the main ITV channels in SD.

 

[Longshanks]

Thanks. I’ll try and move tv to another position, although the current position in the conservatory is clearly “too good” for the Panasonic. Yes, I did speak to guy. (Guy who did original job) This is where “snippets” of info can be a good thing. Ie- risk of being challenged about what/why he said x or y, struggling to recall technical detail etc.

Gist is, he said too much signal in his experience was an issue where 70db or more. (In our case his meter was showing 50-pretty good in view of loft splitter and long cable run) He advised me to try another filter before the attenuator. (Photos attached) This seemed to work for a few days, but issue reappeared yesterday.

Thanks

 

[Lucid]

Gist is, he said too much signal in his experience was an issue where 70db or more. (In our case his meter was showing 50 - pretty good in view of loft splitter and long cable run) He advised me to try another filter before the attenuator. (Photos attached) This seemed to work for a few days, but issue reappeared yesterday.

This is what I mean by snippets of information. At the beginning of the thread you said your signal strength and quality is very strong. Now it turns out you're running at 50dB or thereabouts, which is a decent signal, but it's not "very strong". This isn't the sort of signal level that oversaturates TV tuners, particularly not ones from a decent brand such as Panasonic.

For testing purposes I can run my unamplified low gain Log Periodic aerial's signal with a peak output of 72dBuV through a Humax PVR loop-thru and then through a legacy Sky box RF loop-through and get 82dB at the aerial socket. This is well above the upper limit of the tuner's recommended signal strength range. This signal goes in to my Panasonic GX800. The TV is perfectly happy with that.

I've just tested the same on a customer's Panasonic TX32LZD81 (c. 2008-2009, Freeview SD, Freesat HD) that I have here and with equally happy results. At 82dBuV the signal Quality reading never varies from 10 on the 0~10 scale reading on this set for the main services that should reach my location. Attenuating down to 38dBuV is the threshold point when signal Strength has dropped but Quality is still 10. At 54dBuV on this set I get 10 for both Q and S.

The main service muxes for my area all transmit at 100,000W. However, I can also pick up the low power transmissions down to 1000W for what should only be available to the Manchester metropolitan area. With this I get just 31dBuV signal strength direct off the aerial and my meter rates as a Poor/Fail for signal Quality. The LDZ81 TV though is happy to report about 7 on Q and 4 on S. There's no evidence of picture break-up. The situation changes if I run through the gain stages of the loop-thru connections on both the Humax and the Sky box; Q drops to 5 but S lifts to 7. This is crude proof of how amplification adds noise which in turn reduces signal quality.

50 dB as a signal level doesn't tell me much about what's going on with your signal other than what's happening with one of the muxes. Is 50dB the signal from one of the strongest muxes or the weakest? We don't know, and I'm guessing you don't know either because you didn't know to ask. The fact that the PVR is working fine would suggest that the aerial is at least reasonable match to the local transmitter otherwise you'd have problems with that too.

The point here is that 50dB isn't going to oversaturate a tuner, so your original comment about the signal being very strong was a bit of a red herring. That's always one of the pitfalls of trying to diagnose remotely; we have to deal with an OPs impression of what's going on, and that might not accurately reflect the reality.

The bottom line here is that your don't need to reduce the signal level for the TV. It's only going to make things worse, not better. You've eoither got a problem in the signal chain from the PVR to the TV ( and that includes the possibility of a broken RF input on the TV ), or the tuner in the TV is failing. I have to be honest and say I haven't yet encountered a failed tuner unless something catastrophic has happened such as a lightning strike. That doesn't mean to say it will never occur, but it's incredibly rare in my experience.

I would start by taking the TV to another aerial point in the house, one that isn't connected to this new aerial, and one that you know works fine with another TV. Whilst you're about it, check there's still a centre pin in the TV RF input. If the TV works fine in the new location then you know the issue is something in the conservatory. Where the TV still struggles in the new location then it has to be something in the TV itself. I take it you've checked the tuning?

 

[Longshanks]

This is what I mean by snippets of information. At the beginning of the thread you said your signal strength and quality is very strong. Now it turns out you're running at 50dB or thereabouts, which is a decent signal, but it's not "very strong". This isn't the sort of signal level that oversaturates TV tuners, particularly not ones from a decent brand such as Panasonic.

For testing purposes I can run my unamplified low gain Log Periodic aerial's signal with a peak output of 72dBuV through a Humax PVR loop-thru and then through a legacy Sky box RF loop-through and get 82dB at the aerial socket. This is well above the upper limit of the tuner's recommended signal strength range. This signal goes in to my Panasonic GX800. The TV is perfectly happy with that.

I've just tested the same on a customer's Panasonic TX32LZD81 (c. 2008-2009, Freeview SD, Freesat HD) that I have here and with equally happy results. At 82dBuV the signal Quality reading never varies from 10 on the 0~10 scale reading on this set for the main services that should reach my location. Attenuating down to 38dBuV is the threshold point when signal Strength has dropped but Quality is still 10. At 54dBuV on this set I get 10 for both Q and S.

The main service muxes for my area all transmit at 100,000W. However, I can also pick up the low power transmissions down to 1000W for what should only be available to the Manchester metropolitan area. With this I get just 31dBuV signal strength direct off the aerial and my meter rates as a Poor/Fail for signal Quality. The LDZ81 TV though is happy to report about 7 on Q and 4 on S. There's no evidence of picture break-up. The situation changes if I run through the gain stages of the loop-thru connections on both the Humax and the Sky box; Q drops to 5 but S lifts to 7. This is crude proof of how amplification adds noise which in turn reduces signal quality.

50 dB as a signal level doesn't tell me much about what's going on with your signal other than what's happening with one of the muxes. Is 50dB the signal from one of the strongest muxes or the weakest? We don't know, and I'm guessing you don't know either because you didn't know to ask. The fact that the PVR is working fine would suggest that the aerial is at least reasonable match to the local transmitter otherwise you'd have problems with that too.

The point here is that 50dB isn't going to oversaturate a tuner, so your original comment about the signal being very strong was a bit of a red herring. That's always one of the pitfalls of trying to diagnose remotely; we have to deal with an OPs impression of what's going on, and that might not accurately reflect the reality.

The bottom line here is that your don't need to reduce the signal level for the TV. It's only going to make things worse, not better. You've eoither got a problem in the signal chain from the PVR to the TV ( and that includes the possibility of a broken RF input on the TV ), or the tuner in the TV is failing. I have to be honest and say I haven't yet encountered a failed tuner unless something catastrophic has happened such as a lightning strike. That doesn't mean to say it will never occur, but it's incredibly rare in my experience.

I would start by taking the TV to another aerial point in the house, one that isn't connected to this new aerial, and one that you know works fine with another TV. Whilst you're about it, check there's still a centre pin in the TV RF input. If the TV works fine in the new location then you know the issue is something in the conservatory. Where the TV still struggles in the new location then it has to be something in the TV itself. I take it you've checked the tuning?

I rest my case M’lud.

Obrigado