Philips 819 line TV receiver.

[FERNSEH]

This Philips 819 line TV receiver needs attention again. Tuner problems.
The contact springs were not making contact with studs on the coil biscuits.

Readjusting the contact bar slightly has effected a cure. The receiver works best on channel F11. I was hoping that F8A would work but the coil formers have become deformed so it's not possible to adjust the oscillator coil cores. It's the same for all the other channel biscuits. Band 1 channels work in a fashion but I'd prefer to use a Band 3 channel.

The vision IF bandwidth is restricted to 6Mhz so the full potential of the 819 line system cannot be realised. The vision IF amplifier has only two stages using EF80 pentodes.
The set was made in 1958.
Line count apart this set is very similar to the 405 line Philips model 1768U although the French set employs a mains transformer which can be adjusted for 110 130 and 220 volt mains supplies.

Signals are supplied by the owner's Aurora converter.

DFWB.

[AJSmith625]

That looks a very well made set and an excellent picture as well. Shame its not the full IF bandwidth for the system E signal. I only ever saw an 819 line picture in the flesh once and that was on a continental Sony 9-90UM while on a trip to France in the early 1970s. Again this set having the restricted vision IF bandwidth. I was still amazed at hardly not being able to make out the line structure on the 9 inch screen.

Alan.

[Nuvistor]

Possibly if the full bandwidth had been used it would have required another IF stage to compensate for loss of gain.

[FERNSEH]

The full video IF bandwidth 819 line receivers had four stages of amplification but as usual when cost cutting became the norm two stages of IF narrow bandwidth amplification was considered adequate.
Nevertheless, as Alan noted the 1958 Philips receiver is constructed to a very high standard. Easy to service. To remove the chassis, disconnect the frame and line scan coil plugs, the loudspeaker plug, take off the CRT base socket and EHT connector. Remove the 6mm chassis securing screws and withdraw the chassis. Takes less than five minutes to do all this.

DFWB.

[Jac]

Hello David,

Do you know the type number of this set?
The accessibility for service looks excellent, which is always a great help!

Jac

[Peter.N.]

Never seen an 819 line set before although I often saw two 819 pictures side by side in the '50s. That sets looks modern for 819.

Peter

[FERNSEH]

PeterN wrote: "Never seen an 819 line set before although I often saw two 819 pictures side by side in the '50s."

There is still a few older 819 line sets upstairs if anyone wants one.

"That set looks modern for an 819"
I have a 24" slimline 819 line receiver. Might be a dual standard model 819 and 625 system L.

Hello Jac, the owner of the set brought the in for repair without the back, but it's most likely it doesn't have one anyway. So it's not possible to determine the model number.

DFWB.

[FERNSEH]

Attachments show the Philips valve position chart and the RF and IF amplifiers in an earlier 819 line receiver, a 17" HMV single channel model made about 1954.

DFWB.

[FERNSEH]

Attachments show the sync pulse waveforms generated by the Aurora standards converter. Note there is only two broad frame sync pulses. The frame pulses are 20microseconds wide, half the figure of the 405 broad frame pulses.
Scope set to 50 microseconds/division. X10 probe connected to the cathode of the CRT.

DFWB.

[Jac]

That's interesting David.

Kerkhof and Werner in the 1952 book "Television", give a somewhat different frame sync pulse. See attachment.
I found the same in a French book, but it may very well be that later on the standard has changed.

Jac

[peter_scott]

See also: https://www.vintage-radio.net/forum/...ad.php?p=23061

(I think the reference to my reception suggests it was actually 625 I was receiving and not 819.)

Peter

[FERNSEH]

It came as a surprise to see the frame sync with two broad pulses. The common consensus here was that the 819 line system sent only one broad frame sync pulse.
I've traced out the sync and timebase oscillator circuits and will in due course post up the circuit diagrams.

DFWB.

[Jac]

The signals must originate in the Aurora.
The converted video output of the Aurora should show the same waveform (which looks good).

Jac

[peter_scott]

I think Darryl must have confused one broad pulse with one line period.

441 line standard also has just one broad pulse. What does Aurora transmit for 441?

Peter

[Jac]

I agree with Peter that there could just be the wrong sync signals from the Aurora. Or the standard changed.

On the other hand, it seems to work fine?

Jac

[FERNSEH]

The 441 line system transmitted from the Eiffel Tower has like the 405 line system eight broad frame sync pulses. Like the 405 line system 385 lines carry the picture information. According to the service documentation for the Philips TF390A TV receiver the "d'effacement des signaux de vision" is 28 lines per picture field, approximately 25mS. (The 405 field blanking period is 1.4mS. =14 lines per picture field.)

DFWB.

[FERNSEH]

"On the other hand, it seems to work fine?"
Jac

Frame hold is excellent, except for a slight hooking effect at the top of the picture if the line hold control is incorrectly set.


DFWB.

[peter_scott]

The 441 standard I quoted was German. Perhaps the French changed it after the war.

Peter

[kan_turk]

France continued with 'German' 441 line system until 1956 when fire destroyed the Eiffel tower transmitter

J

[German Dalek]

Originally Posted by peter_scott

The 441 standard I quoted was German. Perhaps the French changed it after the war.

Thats a really complicated case!
I am collecting many books, literature about the french history of Television.
So all is old stuff!
In these years the French themselfs talked about the 441, 450 and 455 lines
standard!
Take your choice!

Best regards,
German Dalek