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Saturday, January 29, 2011

VOXSON Mod. 1202 YEAR 1972.







An awesome B/W portable television from VOXSON.

It has 12 Inches and 4 programs preselections plus 2 incorporated antennas.
It can even power supplyed by a 12volt source.
Recently, it has become more popular than ever to watch TV in a car as the number of cars increases. In general, a storage battery of 12 volts is used in small cars while one of 24 volts is used in large cars so that there is a disadvantage that a separate power supply device is required for driving a TV set in compliance with the respective battery used in the car. The present invention relates to a power supply circuit of a television receiver used in an automobile, and in particular to a power supply circuit of a television receiver which enables two different voltages from two kinds of supply respectively mains at 220v and dc 12v.

Red Voxson 1202 Tv set design by Rodolfo Bonetto in 1972.
"the color of this unit is a Vintage red (brownish red)... almost terracota"
This TV has a very special shape ... totally symmetrical !!
" Rodolfo Bonetto has drawn many televisions for Voxson at this time, all as well drawn and also different... each others... "


Rodolfo Bonetto

(Milan 1929-1991) designer. Began his activity in 1958 operating in the durable consumer goods sector and industrial goods sector in various fields: from domestic appliances to bathroom fittings, automobiles, musical instruments, radios and airplane instrumentation panels. “A cultured factory worker”, as V. Gregotti described him, he successfully managed to combine a thorough understanding of production technologies and materials with ergonomic considerations and a very ethical attitude to formal research. He taught at the Hochschule für Gestaltung of Ulm (1961-1965), and has been awarded six Compasso d’Oro for objects such as the Sfericlock alarm clock (Veglia Borletti, 1963); the O.C.N. numerical control machine tool (Olivetti, 1967); the automatic microfilm apparatus (BCM, 1970); the interior for the 131 Supermiriafiori (Fiat, 1978). Between 1972 and 1975 with N. Matsunaga, he designed the tooling centre Horizon 2 (Olivetti) up to the Wiz multi-purpose generator. Creator of the Fire engine (1984) for Fiat, the Rotor, public telephone for Sip (1989) and the mechanism for automatic gate opening Cross 6 (Novotecnica), he has been a member of national and international juries and president of Ic sid from 1981 to 1983. Bonetto is the only Italian designer never to have put his name to architectural projects, as he was always solely interested in large-scale production. After his death, he was dedicated the Compasso d’Oro 1991 as a tribute to his overall activity, which now continues with the Bonetto Design Studio, run by his son Marco, who, in 1994, founded the Bonetto Design Centre in Montecarlo dedicated to his father’s memory, a centre for ideas and services for the new areas of design.
[from A. Pansera ( edited by), Italian Design Dictionary, Cantini, Milan 1995, in the updated volume (January 1998, edited by Tiziana Occleppo) from the CD Rom “Navigando nel design” (edited by A . Pansera, art direction Oderso Rubini for Studio Equatore) 1995]

Rodolfo Bonetto had his first meeting with Raimondo Guzzini in 1967, as is shown by an entry in the records in which Bonetto used to carefully note down all his working relationships. He designed for the Fratelli Guzzini until 1971 and up to 1986 for iGuzzini illuminazione.


In the end of the 60's  increasingly attention was focused on the varicap diode tuner as the latest, sophisticated means of television receiver frontend tuning in both colour and black and white sets.
 The main purpose of this article is to investigate the servicing problems associated with this comparatively new method of tuning.

First however let's briefly recap on the principles involved in this tuning system:

 The tuners use variable capacitance (or "varicap") diodes as the variable tuning elements: the effective capacitance of the diodes is controlled by the reverse bias applied across them, tuning being achieved by varying this voltage. As the reverse bias across a varicap diode is increased so its junction depletion region widens thus reducing its capacitance.
A VHF/ UHF television tuner is constructed in accordance with the present invention includes a preselector tuned circuit having a solid state voltage controlled capacitor as its tunable element, a radio frequency amplifier coupled to the preselector circuit and alsoother circuit to perfect the signal receiving capability and the application the like.

Considering the Mechanical Tuner Problems:

To get the servicing problems in perspective let us next consider the tuning arrangements previously used.
 The earliest of these, employed on v.h.f., was the switched tuner which was either of the turret or incremental type.
 The turret tuner substituted a coil bearing "biscuit" mounted on the rotating drum or turret when channels were changed. Twelve positions were normally provided, with a fine tuning knob to adjust the local oscillator frequency. As its name suggests the incremental tuner simply added more inductance to the tuned circuits at every downward channel movement: thus the highest inductance was present on channel one and the least on channel 12 (which normally covered 13 as well with manipulation of the fine tuner).
The movement towards u.h.f. TV working, initially with dual standard sets and later with single standard ones, brought about the need for u.h.f. tuners. In the earliest u.h.f. receivers valve tuners which were not particularly efficient were used.

The drive mechanism was usually a dual  speed rotary system calibrated from channels 21 to 68. Experience in the field indicated that 625 line television was in many cases considered by the viewer to be inferior to 405 -line reception, on account of the poor signal to noise ratio achieved by the valve tuners. Many viewers were not prepared to use external u.h.f. aerials of course, having achieved satisfactory reception on v.h.f. with an indoor aerial: this aggravated the situation even more.
Another aspect which caused difficulty was the care needed to tune in a u.h.f. channel using a rotary tuner covering the whole of Bands IV and V. Many viewers simply could not tune in BBC 2  or ZDF or ORF or any channel correctly with such a tuning mechanism, finding that they had passed right over the channel they wanted before realising what they had done.
The advent of transistor tuners rapidly improved the quality of u.h.f. reception but use of a rotary mechanism was continued by many manufacturers. Thus while potential reception was improved the same tuning difficulties remained and viewers continued to gravitate towards 405 line viewing using the "old faithful" switched tuner. The operational breakthrough came with the introduction of the push-button u.h.f. channel change. 

The mechanism is basically simple. Adjustable push buttons press down on a lever bar which in turn rotates the tuner's variable capacitors to the appropriate position. Each button is capable of tuning over the entire u.h.f. bands and this leads to customer confusion at times when after some adjustments which were too heavy handed they find themselves receiving ITV on a BBC button or a ORF and ZDF broadcasting or any channel possible !

Mechanical Faults:

 Mechanical tuning obviously has its snags. There are for example contact springs which earth the tuning capacitor and go intermittent. This gives rise to the most random tuning defects, capable of driving the. most patient viewer to a state of total exasperation. It is also possible for the rotation mechanism to hang up and jam intermittently, or just become sticky, so that the reset accuracy of the mechanism is impaired and the receiver has to be retuned every time the channel is changed.
The vanes in the tuning capacitor can also short out at different settings, thereby eliminating some channels. The  Varicap Tuner It will be seen then that mechanical defects can cause very irritating fault symptoms. If one thinks along the lines that anything mechanical is nasty, then the elimination of mechanical parts can only be to the good.

The logic of this is splendid provided the electronic replacement for the mechanical system is more reliable! Otherwise we are leaping out of the frying pan into the fire! In the light of experience gained with mechanical tuning devices it seems great that with the varicap tuner we have at last dispensed with the dreaded rotary tuning capacitor, replacing it instead with a variable voltage to the tuner. 
Let us think about this however since things are never quite as simple as they first appear. The tuning voltage has to be variable in order to tune the receiver. Obviously then a means of varying the voltage has to be provided to act as the tuning control.
As it is a voltage that has to be varied the tuning control takes the form of a potentiometer., Now we have returned to a mechanical system again, though in a less complex form.
A potentiometer is required for each channel, selected by pressing the appropriate channel button.

We have lost a tuning capacitor and its rotating mechanism and gained a set of pots and selector switches therefore. Provided the pots and switches are mechanically more reliable than the tuning capacitor we should be better off-or should we? 

Need for Voltage Stabilisation.
 The voltage selected by the pots cannot be allowed to drift otherwise the receiver will go off -tune. The voltage supply to the potentiometers has to be stabilised therefore and a stabilising zener diode or integrated circuit (TAA550) .is needed for this purpose.

Any failure in this part of the circuit will give rise to tuning drift or worse, a total loss of reception. A short-circuit TAA550 for example will completely remove the tuning voltage while if it is open circuit the tuning can vary with picture brightness. Likewise any intermittency in the potentiometers or associated switching and/or resistors can also cause problems.

Relative Reliability of Tuners:

 It  will be seen then that in order to lose our troublesome mechanical arrangement we have had to introduce considerably more electronics which we trust are going to be more reliable. In addition we have not so far considered the relative reliability of the varicap tuner itself compared with the mechanical type. Since two r.f. transistors are generally used to compensate for the reduced Q of the varicap tuned circuits we immediately have twice the likelihood of an r.f. stage breaking down! 
And being semiconductors the varicap diodes themselves are more likely to fail than the sections of a ganged tuning capacitor. It is reasonable then to conclude that if mechanical faults are the most prevalent the use of varicap tuners will make life easier. Mechanical faults are generally not too difficult to sort out however and the field engineer can often cope with them in the home. 
Can the same be said of the varicap tuner? It seems that this type of tuner does not need so much attention as its mechanical counterpart but is likely to throw up some much more difficult faults when it does, resulting in bench repairs being needed. So far my own experience has indicated that varicap tuning faults nearly always need servicing on the bench.
Generally speaking it seems true to say that varicap tuners themselves are adequately reliable: the snags result from the tuning system and stabilised power supply.

Tuning Drift with Varicap Tuners:

 If a varicap tuned receiver is constantly drifting off tune the +30V supply should be the number one suspect. It is best to connect an Avometer permanently to the supply so that it can be precisely monitored-if necessary write down the exact voltage measured.
 If the receiver drifts, check the voltage. If it has changed, even slightly, this may well be enough to be the cause of the fault. To pinpoint and confirm the diagnosis aerosol freezer should be applied to the stabiliser i.c. or zener. If the voltage returns to normal or changes wildly for the worse the stabiliser is almost certainly the cause of the trouble and should be replaced.
A prolonged soak test should then be carried out. Another point concerning varicap tuners arises with their use in colour receivers.


 There were  makers of the most expensive colour receiver on the market still didn't use a varicap tuner but instead use a mechanical one. The makers' claim is that the signal to-noise ratio of the varicap tuner is inadequate for their colour standards. Undoubtedly the results obtained on the receiver seem to confirm this. Interestingly, the same manufacturers use varicap tuners in their black -and -white receivers, and the tuning button system is often full of troublesome intermittent contacts. The varicap tuner has its advantages and disadvantages then. Probably the simplest comment would be to say that when it is good it is very very good but when it is bad it is horrid!



VOXSON was an Italian manufacturer site in Rome in Italy.

It was founded in 1952 by the engineer Arnaldo Piccinini with the name FARET, which stays for Fabbrica Apparecchi Radio e Televisione S.p.A..

The activity begun with radio and television fabrication factory.

It have had almost an immediate success on the market and at the end of the 1950's it have great penetration in the market with lot of sales even in extra market such as Germany.



With some unclear involvements in the 1980's VOXSON was sinking , and with classics Italian industry destroy style it was treatened like a tennis ball between that and this guy and mate; and all of this degraded rapidly the original identity of this industry.

Today VOXSON is selling LCD crap like many others with parts coming from there and there.

The destiny of such industry seems all around the same.


(To see the Internal Chassis Just click on Older Post Button on bottom page, that's simple !)

Further Notes and readings:

^ Produce autoradio da ventisei anni, in L'Unità, 28 ottobre 1977. ^ G. Dell'Aquila, Alla Voxson non bastano o e sovvenzioni, in L'Unità, 30 agosto 1977. ^ F. Ferrarotti, La città come fenomeno di classe, Editore Franco Angeli, 1975, p. 69 ^ A. Castagnoli, E. Scarpellini, Storia degli imprenditori italiani, Einaudi, 2003, p. 333 ^ (EN) "EMI buys 50 P.C. of Voxson, TV Maker", articolo della rivista Billboard del 24 aprile 1971. ^ "VOXSON / L'EMI VUOLE CEDERE IL POSTO ALLA GEPI", articolo del periodico L'Espresso vol. 21, numero 8 del febbraio 1975. ^ Atti Parlamentari - Camera dei Deputati, SEDUTA DI GIOVEDÌ 29 SETTEMBRE 1977 (PDF), su Legislature.Camera.it, 29 settembre 1977. URL consultato il 22 gennaio 2019.

 ^ Dal sito credfed.it ^ Informazione tratta dal sito europeanmemories.eu ^ "ITT E REL DANNO VITA ALLA VIDITAL ASSORBIRA' 750 LAVORATORI VOXSON", Repubblica, 8 febbraio 1985 ^ "VA A FONDO LA VOXSON COSTRETTA A LICENZIARE", Repubblica, 11 settembre 1987 ^ "QUESTO IL FALLIMENTO REL 377 MILIARDI SPESI NEL NULLA", Repubblica, 2 ottobre 1987 ^ "LA REL ENTRA NELLA VOXSON PER SALVARE 300 OCCUPATI", Repubblica, 9 ottobre 1987 ^ "BATTAGLIA DA' IL VIA AL RIFINANZIAMENTO DELLA VOXSON", Repubblica, 22 ottobre 1987 ^ "SOMMERSI E SALVATI CON I SOLDI REL", Repubblica, 19 ottobre 1990 ^ "REL LIQUIDATA LO STATO 'ESCE' DALL'ELETTRONICA", Repubblica, 21 dicembre 1990 ^ "la Maserati suona l' ultima sirena", Corriere della Sera, 30 marzo 1993 ^ "Aspettando Rete4 Di Stefano fa trading", Corriere della Sera, 25 febbraio 2008



5 comments:

  1. nice one! i kind of inherited this tv from my dad when it reappeared during or last move to another house.
    it still works, but i cant tune in any programms because theyre all digital now :-(

    ReplyDelete
  2. Not exactly !

    Get a DVB-T Decoder with RF MOD Output and a demixer unit (RF to VHF-UHF) problem solved !

    ReplyDelete
  3. To anyone who wants to watch any old timer CRT TV' to display todays programms sent out in digital just recover that VHS tape player from the attic connecting the aerial OUT to the TV and the digital decoder scart to the VHS player. Thats it!

    ReplyDelete
  4. @Giorgio Brufatto,

    ..............and guess what if they already scrapped away that "VHS player"..............

    ReplyDelete
  5. Any idea where I could get the cable that went with it? I have one of the triagle shaped TV's by Voxson but no power cable...

    ReplyDelete

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