PYE V4

One of Pye's more striking sets, the front of which went on to get the knickname of the washboard set, though whether that was a knickname given to it in the 50's or whether it was given by us collectors I'm not too sure.

The glass screen at the front of this set is deliberately sloped, the idea being to reduce the effect of reflections from objects in the room, though to be honest this was has been the worst set I've photographed so far ... because of reflections !

Fig. 1 : TV Vision Signal

Pye continued their lead in television with this set by introducing "Automatic Picture Control". With radio, the average amplitude of the trasmitted signal is constant regardless of whether the tranmitted sound is loud music or total silence ; the average signal of the received signal could therefor be used to adjust the radio's gain so as to keep the volume constant regardless of fading of the received dignal. However the amplitude of the transmitted vision signal (fig.1) varied depending upon the picture content, having a low average value with a dark scene (A) and much higher value with a very light scene (B). Thus using the average signal to adjust the gain of the set (as some manufactures did indeed use) would result in lightening of dark scenes and darkening of light scenes. However there is one small section of the signal that is a true indication of received signal strength. There is a short (few microseconds) part of the waveform which is a reflection of signal strength (point 'C') which is at ~1/3rd of the peak white signal. The Pye V4 samples the voltage at this point and uses it to automatically adjust the gain of the receievr so as to maintain 'C' at a constant level.

Another feature of the set is the use of flywheel syncronisation. OK, so other manufacturers had used this method previously but in the majority of cases it was only added to their fringe area models. The Pye V4 has it fitted as standard.

Cabinet is good. However there appears to have been a fair bit of work around the chassis where some wiring has clearly been replaced and there is a mixture of dusty old valves and shiney new ones. The hole in the back cover for the focus control has been significantly enlarged yet there is no focus lever - not sussed whats going on here. Also, whilst it's not unusual to find an old telly with its mains lead chopped of (for safety), why on earth was this set's aerial lead chopped ?