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JBR
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24-02-2018, 12:01 PM
1

Panasonic DMR-BWT850 BD/DVD recorder problem

Hi,
I have noticed that, occasionally, a timer recording I have set on this unit fails to record for some reason. I would put this down to some external problem, such as the transmission being cancelled, but my old recorder - DMR-BWT720 - has recorded the same programme correctly.

On Monday, therefore when the same problem occurred, I made a note of exactly what had been set (on both units):
1830 – 1900 BBC2 Great British Railway Journeys
1900 – 2000 Horror Star Trek TNG
1930 – 2000 ITV Coronation Street FAILED TO RECORD
2030 – 2100 ITV Coronation Street
2030 – 2100 BBC2 University Challenge
2100 – 2200 BBC2 Collateral
2100 – 2200 Ch 4 24 Hours in Police Custody

Clearly, there has been no attempt to set more than two programmes at the same time and, more importantly, my old recorder did record all programmes correctly.

I wonder whether there may be some obscure setting that I have failed to notice. Is it possible, for example, that if I was watching a third channel at the time (1930 in this instance) the recording would not take place for that reason? My experience in the past has been that if this is the case a message would appear on the screen warning that a recording is about to begin, although I didn't see such a thing on this occasion. I haven't seen anything along these lines in the settings menu.

I'd be grateful if anyone could offer some advice about this. The unit is still under warranty, but if it is simply a matter of changing some sort of setting, that would be a better alternative to having it repaired and, possibly, finding all previous recordings deleted!
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24-02-2018, 07:08 PM
2

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

Ok some questions

Do both units have 2 tuners in them each?

Or does one have 3?

With 2 tuners, a device can record 2 different channels and POTENTIALLY allow you to watch a 3rd. The ability to watch that 3rd depends on the specific channel you want to watch.

TV channels all belong to groups of channels called multiplexes. The BBC channels for example are all in one group, the ITV channels are in another and so on.

The tuners in the device tune into a multiplex, not into a specific channel.

So one a tuner is directed to a specific multiplex, EVERY channel within that multiplex group is viewable, even if you are recording a different channel IN THAT SAME MULTIPLEX.

There are to my mind 2 things that could be causing your problem.

The first is that you decided to watch a 3rd channel before one of the programmed channels started and that 3rd channel WAS NOT in the same multiplex group as the programmed channel. That could/would have prevented a programme from recording, though on most devices there would have been a warning on-screen to tell you about it, and usually a device will automatically change stations to the programmed channel anyway.

The second likely cause of your problem are the settings you have set up for recording. It's normal to set up a length of padding time both at the start and end of the programme. This allows the entire programme to be recorded if say the programme is broadcast slightly early or late. My recording usually have a 3 min pad at the start and 5 mins at the end.
If you haven't specifically set this up yourself, the device might already have a default.

The net result of this is that the machine starts recording before the programme starts. So where your programmes overlap you may have issues.

For example:

2030 – 2100 BBC2 University Challenge
2100 – 2200 BBC2 Collateral
2100 – 2200 Ch 4 24 Hours in Police Custody

Here you have 3 programmes

Tuner 1 will be using the BBC multiplex for University Challenge
Tuner 2 will be using the BBC multiplex also to record Collateral

The third programme should struggle because at 2100 hours the first 2 programmes are already still recording (because of the start and end padding times)

These are the 2 most likely problems imo.
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24-02-2018, 07:53 PM
3

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

Originally Posted by Realist ->
Ok some questions

Do both units have 2 tuners in them each?

Or does one have 3?

With 2 tuners, a device can record 2 different channels and POTENTIALLY allow you to watch a 3rd. The ability to watch that 3rd depends on the specific channel you want to watch.

TV channels all belong to groups of channels called multiplexes. The BBC channels for example are all in one group, the ITV channels are in another and so on.

The tuners in the device tune into a multiplex, not into a specific channel.

So one a tuner is directed to a specific multiplex, EVERY channel within that multiplex group is viewable, even if you are recording a different channel IN THAT SAME MULTIPLEX.

There are to my mind 2 things that could be causing your problem.

The first is that you decided to watch a 3rd channel before one of the programmed channels started and that 3rd channel WAS NOT in the same multiplex group as the programmed channel. That could/would have prevented a programme from recording, though on most devices there would have been a warning on-screen to tell you about it, and usually a device will automatically change stations to the programmed channel anyway.

The second likely cause of your problem are the settings you have set up for recording. It's normal to set up a length of padding time both at the start and end of the programme. This allows the entire programme to be recorded if say the programme is broadcast slightly early or late. My recording usually have a 3 min pad at the start and 5 mins at the end.
If you haven't specifically set this up yourself, the device might already have a default.

The net result of this is that the machine starts recording before the programme starts. So where your programmes overlap you may have issues.

For example:

2030 – 2100 BBC2 University Challenge
2100 – 2200 BBC2 Collateral
2100 – 2200 Ch 4 24 Hours in Police Custody

Here you have 3 programmes

Tuner 1 will be using the BBC multiplex for University Challenge
Tuner 2 will be using the BBC multiplex also to record Collateral

The third programme should struggle because at 2100 hours the first 2 programmes are already still recording (because of the start and end padding times)

These are the 2 most likely problems imo.
Thanks for that, Realist.

Addressing each of your suggestions in order:

Each of the units has only two tuners, in fact both units are basically the same except that one is a more recent version. Incidentally, both are the only examples I could find that combine two Freeview tuners and the ability to record and copy to Blu Ray discs and DVDs.

Yes, I'd heard of multiplexes, and I may well have been watching a programme on a third channel at the time, although I don't remember what that might have been. I do remember that, on occasion, I have been watching a third channel whilst two others were being recorded, so I'm sure that it is possible to do that.

On the same basis, I do remember on a number of occasions seeing a message of the type you describe that a recording is about to start and, on those occasions, I have found that the programme I was watching is terminated in favour of the two I have set to record. I don't remember that happening on this particular occasion when one failed to record.

No, I definitely didn't set any padding on the timer programmes I listed above. That was the first thing that crossed my mind. I used to do that with an earlier Humax recorder I once owned: I'd set a couple of minutes of padding before and five or so at the end to be applied automatically to all timer recordings, as so many TV stations could not be relied upon to send the appropriate signals at the right time! However, these two Panasonic units don't feature that facility - as far as I know!

It had occurred to me that this unit that failed to record may have had some sort of setting to disable the automatic reverting to a multiplex in use by the timers but, having ploughed through the handbook yet again, I can see no such thing!

Anyway, thanks for all the helpful suggestions. I think the best thing I can do in future is not to set the unit to watch a third channel whilst two others are on timer record. As I don't really know which channels are on which multiplexes, I shall not even attempt to work that out. I must remember to watch a third channel on the second unit or directly from the TV tuner in future, and see if the problem happens again.

Thanks again.

Incidentally, you are the only person who has thought to offer help, including those on another forum that specialises in such technical matters!
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25-02-2018, 12:12 PM
4

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

There's likely some default padding so check for that.

Do the programmes you've successfully recorded always start bang on the start of the programme? Or are there a couple of adverts first? If the latter then the device is adding a couple minutes on.
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25-02-2018, 01:26 PM
5

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

It varies. Quite often the recording does start a little early, but occasionally a little late. Same with the ending.

I put this down to the broadcast company not sending the start/end signals precisely on time, especially on the amateur channels (everything except BBC, ITV, Ch4 and Ch5!

There is nothing in the book of lies that suggests any default padding.

Anyway, if you see my list above, the failed recording would have started well within one other recording and finished at the same time as that recording, so there would never have been more than two channels being recorded.
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28-02-2018, 09:48 AM
6

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

I'm impressed with the level of detail in these posts; makes me think that if I had a technology problem it could be addressed here.
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28-02-2018, 11:12 AM
7

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

Originally Posted by Ffosse ->
I'm impressed with the level of detail in these posts; makes me think that if I had a technology problem it could be addressed here.
I know that Realist is very expert in these matters.
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28-02-2018, 01:56 PM
8

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

Just a thought. Have you done a retune recently?

I noticed last week that the Horror Channel wasn't showing anything in the guide listings so either it moved channels or my local transmitter had a problem of some kind.
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28-02-2018, 02:50 PM
9

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

I’ve experienced the same problem as JBR although my recorder’s a Humax .
Most annoying but I’ve always put it down to a transmission problem.
Must say it hasn’t happened since I did a retune it that could simply be coincidence .

Realist I never realised that about padding .
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JBR
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28-02-2018, 03:01 PM
10

Re: Panasonic DMR-BWT850 BD/DVD recorder problem

Originally Posted by Realist ->
Just a thought. Have you done a retune recently?

I noticed last week that the Horror Channel wasn't showing anything in the guide listings so either it moved channels or my local transmitter had a problem of some kind.
Yes, I did a retune just the other day for the very reason that the Horror Channel's EPG was blank. It made no difference, and I have noticed that occasionally they don't seem to have populated their EPG listings. Amateurism, in my opinion.

I did, however, notice one or two extra channels, although not anything that I'd ever watch.

There are, of course, very many trash channels now on Freeview, that whenever I do a retune I have to manually go through the resulting list un-ticking the additional rubbish that appears.
 
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