Philips 819 line TV receiver.

[Geordie McBoyne]

A regular and valued customer has brought this interesting Philips 819 line TV receiver in for repair.  It doesn't need too much doing to it, at least I'm hoping it doesn't.  A fellow forum member has done most of the necessary work and the faults reported are relatively minor.  Sync problems for starters.  These 819 line receivers don't present any real servicing problems, just think of a 405 line receiver with twice the line count.   A special Aurora SCRF converter is used to supply high quality 819 line pictues from a 625 line source.   The test card generated by this converter is the famous "Chevaux de Marly" pattern.
The CRT is the excellent Philips Miniwatt AW43-80, a 90* electrostatic focus tube introduced in the UK and Europe in 1957.
I think these later 819 line receivers have a reduced video bandwidth, about 7Mhz. 11.5Mhz is the ideal figure to realise the full potential of this true high definition system.
The vision IF amplifier has only two stages and uses EF80 pentodes. Earlier 819 line receivers employed four stage vision amplifiers.

Geordie McBoyne.

[Geordie McBoyne]

Attachment shows the RTF test card as generated by the Aurora standards converter.
The frame hold locks the picture over a wide range. Same for the line although I have to establish if it is  direct sync or some kind flywheel synchronising system. Again, like the frame hold the line timebase remains locked over a wide range of the hold control.  Picture contrast is excellent thanks to the employment of a PL83 video amplifier valve.

Geordie McBoyne.

[Derren]

Hi David,  Nice to see you've started having a look at it.  Did it come up like that from switch on?  It sometimes does, but more often than not eventually starts to fail, or next time you switch on, suffers loss of line hold, lack of width, low brightness etc.  I've just been reading some of the forum threads, I hadn't realised how ill you had been and that you were supposed to be taking it easy!  I've been out of touch with the forums since my mother died at the end of last year and have only just joined this one.  Please don't feel you have to do anything you can't manage or are not supposed to be doing!!

[Murphyv310]

What CRT is in the set? Is it a miniwatt or Mullard?

[Terry]

Trevor, either branding could be applied to a tube manufactured in any Philips Group factory, so why does the brand matter?

If it's the original CRT it is extremely unlikely to be branded Mullard!

I've been trying to read the code group on the spigot. The first character of the 2nd row looks like '1', in which case it was manufactured at Philips, Eindhoven.

[Murphyv310]

Hi Terry.
I had one of these that I passed on a few years ago, just wondering if it was my old set as I fitted a Mullard AW 43-80. They came with a Miniwatt tube from the factory not a Mullard.

[Murphyv310]

In fact it isn't, as the one I had went to Marion on the VRAT, its line transformer had failed if I'm not mistaken.

[ppppenguin]

You said this set had reduced bandwidth, as did many 819 sets. Were there many sets with full BW? Did ORTF even originate with full BW on 819? By the time of Ampex 2" VTRs I don't think they had any response much above 5MHz, even theough some models would work at 819, notably the VR2000 which was 405/525/625/819.

[Derren]

It would be helpful if by chance anyone knows the model number of this set, we don't have a circuit as yet.  The card back/bottom is also missing and ideally we hope to make a replacement, it would perhaps be helpful to know what it should look like.

[Synchrodyne]

Here are a couple of datapoints on French TV receiver vision bandwidths.

The first is from Wireless World 1959 October, page 456:

“Quotation of the vision bandwidth is also very common in France.  9 Mc/s was the usual figure given but 10 Mc/s was also often quoted.”

The nominal transmitted vision bandwidth was 10.4 MHz.

   

The second is Carnt & Townsend, Volume 2, page 211:

“Cheaper receivers use the same narrow-band I.F. for both standards, but better models use a 9 MHz I.F, with a narrow-band filter after the U.H.F. tuner.”


   

That was referring to early French dual-standard colour receivers, but I imagine that it was derived from preceding dual-standard monochrome receiver practice.


Cheers,

Steve