MIVAR 20L1T YEAR 1990.

 

The MIVAR 20L1T  is A 20 inches comfortable color television with 39 programs PLL synthesized tuning and remote MIVAR TC3, the television tuning system employs a frequency synthesizer system for establishing the tuning of the receiver, featured with a Microcomputer driven synthesis system, coupled to a frequency lock controller chip such as a Philips TSA5511 / SIEMENS SDA3202. This tuner can tune television signals on VHF and UHF band. Recently, frequency synthesizers including a phase locked loop (PLL) have been suggested to accurately generate local oscillator signals at predetermined frequencies corresponding to the various channels which a viewer may select.
The system employed in the tv permits utilization of a frequency synthesizer tuning system which correctly tunes to a desired television station o channel even if the transmitted signals from that station are not precisely maintained at the proper frequencies even in combination of a fine tuning adjustable by the user.To enable operation of the receiver in a fringe area, where it may be desirable to intentionally mistune a channel slightly, manual fine tuning control logic circuitry is employed to disable the frequency offset logic circuit and to permit changing the count of the reversible counter by the viewer to manually fine tune the receiver as desired.
Accordingly, it is an object of this invention to provide an improved tuning system for a television receiver.
It is an additional object of this invention to provide an improved frequency synthesizer tuning system for a television receiver.

PLL SYNTHESIZED TUNING System Concepts:

INTRODUCTION Digital tuning systems are fast replacing the conventional mechanical systems in AM FM and television receivers The desirability of the digital approach is mainly due to the following features * Precise tuning of station frequencies
* Exact digital frequency display
* Keyboard entry of desired frequency
* Virtually unlimited station memory
* Up down scanning through the band
* Station ‘‘search’’ (stop on next active station)
* Power on to the last station
* Easy option for time-of-day clock In addition
" recent "developments in large scale integrated circuit technology and new varactor diodes for the AM band have made the cost-benefit picture for digital tuning very attractive System partitioning is extremely important in optimizing this cost-benefit picture as will be discussed.

SYSTEM DESCRIPTION
A simplified block diagram of a typical digitally tuned receiver is shown in Figure 1 Notice this receiver could be one for AM FM marine radio or television it makes no difference The frequency synthesizer block generates the local oscillator frequency for the receiver just as a conventional mechanical tuner would However the phase-locked-loop (PLL) acts as an integral frequency multiplier of an accurate crystal controlled reference frequency while the mechanical type provides a continuously variable frequency output with no reference Some method of controlling the value of the multiplier for channel tuning must be provided The other RF IF and audio video circuitry will be the same as in the mechanical tuning method There are many different ways to partition the frequency synthesizer system to perform the digital tuning function................


The set has an AV SCART SOCKET and headphones jack rear side located.

MIVAR 20L1T   Television receiver including a teletext decoder :
 
 PREMISE:
 
 In any normal television system, the transmission of the wide band video signals which are to produce the actual picture elements on the screen of the receiver is interrupted between the scannning periods for line and field synchronization purposes. Consequently, there are periods during which no video signals are being transmitted. It is now possible to use these periods for the transmission of data which is not necessarily concerned with the video transmission itself.

Basically, data representable by standard symbols such as alpha-numeric symbols can be transmitted via a restricted channel provided that the rate of transmission is restricted. It is now possible to use periods as aforesaid especially the line times of the field blanking intervals (i.e. the times of the individual lines occurring between fields which correspond with the times occupied by video signals on active picture lines), for the transmission of pages of data. Typically, using 8-bit digital signals representing alpha-numeric characters (7 bits of data plus 1 bit for protection) at a bit rate of 2.5M bit per second, 50 pages of data each consisting of 22 strips of 40 characters can be transmitted repeatedly in a total cycle time of 90 seconds using only a single line of the field blanking period per field of the 625 lines system as operated in the United Kingdom.

Data transmission as described above is already commercially available in the United Kingdom under the name "Teletext", and transmitters and receivers are described in more detail in our U.K. Pat. Nos. 1,486,771; 1,486,772; 1,486,773 and 1,486,774.

Existing teletext displays consist of 40 characters per row and 24 rows per page. The U.K. teletext transmission standard specifies a data rate of 6.9375 Mbits per second (which has proven to be at the upper reasonable limit of transmission rate for system I, B/G system) so as just to achieve transmission of a complete row of text on one video line of the field blanking time.

The advantage of conveying one row of text on one video line is to achieve maximum economy in requirements for transmission of addressing information needed to correctly position the text information on the displayed page. Since whole rows of text are transmitted on each line, only a row number need be transmitted with each data line of text. Row zero which acts as the page demarcation signal requires additional page numbering information and also incorporates various display and interpretation codes appropriate to the particular page. In order to facilitate parallel magazine working every row of text also incorporates a 3-bit magazine number, being the most significant digit of the page number.

The above structure incorporating as it does one text row on every data line thus results in a very efficient utilization of the transmission facility. However, the existing Teletext transmissions do have limitations in so far as they are less satisfactory when in a "graphics" mode as compared with an "alpha-numeric" mode.


 In a teletext decoder circuit the character generator supplies picture elements at a rate of nominally approximately 6 MHz under the control of display pulses occurring at the same rate. These display pulses are derived from reference clock pulses which occur at a rate which is not a rational multiple of 6 MHz. The character generator comprises a generator circuit which receives the reference clock pulses and selects, from each series of N reference clock pulses, as many pulses as correspond to the number of horizontal picture elements constituting a character, while the time interval of N reference clock pulses corresponds to the desired width of the characters to be displayed. The character generator supplies picture elements of distinct length, while the length of a picture element is dependent on the ordinal number of this picture element in the character.
 
 
 

Each Data-line carries data synchronizing and address information and the codes for a Row of 40 characters. The synchronizing information includes a clock run-in sequence followed by an 8-bit framing code sequence. Each Data-line contains a 3 bit code referred to as the Magazine number. A teletext Page includes 24 Rows of 40 characters, including a special top Row called the Page-Header. Each ROW is contained in a corresponding Data-line. A user selected Page is intended to be displayed in place of, or added to a corresponding television picture frame. A Magazine is defined to include Pages having Data-lines containing a corresponding Magazine number. The transmission of a selected Page begins with, and includes its Page Header and ends with and excludes the next Page Header of the selected Magazine number. All intermediate Data lines carrying the selected Magazine number relate to the selected Page.

A SCART Connector (which stands for Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) is a standard for connecting audio-visual equipment together. The official standard for SCART is CENELEC document number EN 50049-1. SCART is also known as Péritel (especially in France) and Euroconnector but the name SCART will be used exclusively herein. The standard defines a 21-pin connector (herein after a SCART connector) for carrying analog television signals. Various pieces of equipment may be connected by cables having a plug fitting the SCART connectors. Television apparatuses commonly include one or more SCART connectors.

Although a SCART connector is bidirectional, the present invention is concerned with the use of a SCART connector as an input connector for receiving signals into a television apparatus. A SCART connector can receive input television signals either in an RGB format in which the red, green and blue signals are received on Pins 15, 11 and 7, respectively, or alternatively in an S-Video format in which the luminance (Y) and chroma (C) signals are received on Pins 20 and 15. As a result of the common usage of Pin 15 in accordance with the SCART standard, a SCART connector cannot receive input television signals in an RGB format and in an S-Video format at the same time.

Consequently many commercially available television apparatuses include a separate SCART connectors each dedicated to receive input television signals in one of an RGB format and an S-Video format. This limits the functionality of the SCART connectors. In practical terms, the number of SCART connectors which can be provided on a television apparatus is limited by cost and space considerations. However, different users wish the input a wide range of different combinations of formats of television signals, depending on the equipment they personally own and use. However, the provision of SCART connectors dedicated to input television signals in one of an RGB format and an S-Video format limits the overall connectivity of the television apparatus. Furthermore, for many users the different RGB format and S-Video format are confusing. Some users may not understand or may mistake the format of a television signal being supplied on a given cable from a given piece of equipment. This can result in the supply of input television signals of an inappropriate format for the SCART connector concerned.

This kind of connector is todays obsoleted !

(The CHASSIS circuits are far better than majority of the sets of the same era of time even highly more expensive than this Mivar TV here, indeed this tv here is in mint condition.)

The set here shown like other Mivar tv's was introducing a novelty in power supply design;Switch-mode power supply with burst mode standby operation:
In a typical switch mode power supply (SMPS) of a television receiver the AC mains supply voltage is coupled to a bridge rectifier. An unregulated direct current (DC) input supply voltage is produced. A pulse width modulator controls the duty cycle of a chopper transistor switch that applies the unregulated supply voltage across a primary winding of a flyback transformer. A flyback voltage at a frequency that is determined by the modulator is developed at a secondary winding of the transformer and is rectified to produce DC output supply voltages such as a voltage B+ that energizes a horizontal deflection circuit of the television receiver and a voltage that energizes a remote control unit.
During normal operation, the DC output supply voltages are regulated by the pulse width modulator in a negative feedback manner. During standby operation, the SMPS is required to generate the DC output supply voltage that energizes the remote control unit. However, most other stages of the television receiver are inoperative and do not draw supply currents. Consequently, the average value of the duty cycle of the chopper transistor may have to be substantially lower during standby than during normal operation.
Because of, for example, storage time limitation in the chopper transistor, it may not be possible to reduce the length of the conduction interval in a given cycle below a minimum level. Thus, in order to maintain the average value of the duty cycle low, it may be desirable to operate the chopper transistor in an intermittent or burst mode, during standby. During standby, a long dead time interval occurs between consecutively occurring burst mode operation intervals. Only during the burst mode operation interval switching operation occurs in the chopper transistor. The result is that each of the conduction intervals is of a sufficient length.
In accordance with an aspect of the invention, burst mode operation intervals are initiated and occur at a rate that is determined by a repetitive signal at the frequency of the AC mains supply voltage. For example, when the mains supply voltage is at 50 Hz, each burst mode operation interval, when switching cycles occur, may last 5 milliseconds and the dead time interval when no switching cycles occur, may last during the remainder portion or 15 milliseconds. Such arrangement that is triggered by a signal at the frequency of the mains supply voltage simplifies the design of the SMPS.
The burst mode operation intervals that occur in standby operation are synchronized to the 50 Hz signal. During each such interval, pulses of current are produced in transformers and inductances of the SMPS. The pulses of current occur in clusters that are repetitive at 50 Hz. The pulses of current occur at a frequency that is equal to the switching frequency of the chopper transistor within each burst mode operation interval. Such qurrent pulses might produce an objectionable sound during power-off or standby operation. The objectionable sound might be produced due to possible parasitic mechanical vibrations as a result of the pulse currents in, for example, the inductances and transformers of the SMPS.
In accordance with another aspect of the invention, the change in the AC mains supply voltage during each period causes the length of the conduction interval in consecutively occurring switching cycle during the burst mode operation interval to increase progressively. Such operation that occurs during each burst mode operation interval may be referred to as soft start operation. The soft start operation causes, for example, gradual charging of capacitors in the SMPS. Consequently, the parasitic mechanical vibrations are substantially reduced. Also, the frequency of the switching cycles within each burst mode operation interval is maintained above the audible range for further reducing the level of such audible noise during standby operation.
A switch mode power supply, embodying an aspect of the invention, for generating an output supply voltage during both a standby-mode of operation and during a run-mode of operation includes a source of AC mains input supply voltage. A control signal at a given frequency is generated. A switching arrangement energized by the input supply voltage and responsive to the first control signal produces a switching current during both the standby-mode of operation and the run-mode operation. The output supply voltage is generated from the switching current. An arrangement coupled to the switching arrangement and responsive to a standby-mode/run-mode control signal and to a signal at a frequency that is determined by a frequency of the AC mains input supply voltage controls the switching arrangement in a burst mode manner during the standby-mode of operation. During a burst interval, a plurality of switching cycles are performed and during an alternating dead time interval no switching cycles are performed. The two intervals alternate at a frequency that is determined by the frequency of the AC mains input supply voltage.
The cabinet is made of a high quality plastic which doesn't know age or degradation at all.

The set here shown is featuring an Orion CRT tube with blackmatrix and performs nice excellent crisp bright colors and pictures. The Speaker  is a wideband type producing very good sound even if only mono.

This MIVAR model was replacing the MIVAR 20C6L YEAR 1989.

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The Story about the MIVAR 20L1T: I've seen this Mivar 20L1T Tv in 1996 submerged under 50cm or more in a violent water flow on a curbside during a very powerful heavy rain storm (which lasted uninterrupted more than 10 days causing several local houses and street heavy damages).

The set was abandoned half opened and completely parts dismounted but it wasn't missing parts (all anyway was washed very good). I brought, this poor thing, at home and fitted all parts under a warm air fan flow for 3/4 days or more, cleaned the parts and checked them. After that I have rebuild the tv and powered up and It was fully working with perfect crystal color pictures and sound thankfully eventually of a very low time of use. I did a couple of mandatory regulations accordingly to Chassis specifications........closed.....tested....runs perfect..................

........today in 2014 it's here on the web showing itself as his revenge to the rain storm and people stupidity.

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MIVAR was in tha era of time the main example of Italian industry capable to produce excellent tellyes with fair buy price combined with optimal quality and simplicity easy of use. The set MIVAR 20L1T here in collection is one example of these.

MIVAR tv Sets have had great features and extreme simplicity toghether with compactness and combined with reliability and durability.
(Basically all what today you won't see anymore !)
Furthermore they were very robust and easy to fix.

It's made by MIVAR an Italian Brand NO MORE ACTIVE In television manufacturing.

A brief note about on Television sets reliability and durability..........................

ANYONE with even the smallest experience of television engineering is bound to come up against that embarrassing question which is always so difficult to answer-"which TV shall I get?" The questioner is usually concerned about obtaining the cheapest and most reliable receiver that is available, and this same approach generally governs the choice between buying when new - restoring in this time. This is perfectly reasonable and often applies to other consumer products apart from TV. 

What does seem a little strange however is that no one ever seems to ask "which TV set gives the best picture?" Why not? Doesn't anyone care, or is the question too complicated to discuss? 

Yet the average person spends five and a half hours a day, every day, watching TV garbage:

The Propaganda TV Machine a.k.a. The Ministry of Truth delivers The Truth from The Government to the people.
At least, that's what they say. In fact, a Propaganda Machine is only employed by The Empire and used to brainwash people into Gullible Lemmings who believe that everything is all right when in fact, it isn't, and that the very people who could help them are their enemies..............

................... so the quality of the picture must be important........................ 

expecially for those football idiots so the they have the motivation to glue their assface on the screen all day long to discover better somewaht in their ignorance.

........Now................It is high time that people began to realise this simple fact, and to take an interest in the quality of the product that absorbs so much of their spare time. There are of course plenty of people who are genuinely interested in good picture quality. It is unlikely for example that so many readers of this Blog would be taking part in the magnificent TELEVISION colour receiver project, but more likely restoring  monochrome receivers or adapting old color ones, if they were indifferent to the quality of the picture obtained at the end of the day. But today times seems changing, the trend started by many readers of Obsolete Technology Tellye !  have had a significative rise up in recovering and restoring old CRT's TV's and started to build up collections by people in many lands worldwide.

 Good CRT  picture quality cannot however be achieved merely by connecting together the appropriate groups of circuits. Sometimes in fact even well established designs can present problems if they are assembled in a different way to the original or with non-standard components. 

So what constitutes good picture quality and what do you do when things go wrong? 

It is not much use delving into the textbooks because they are strangely unhelpful about this sort of thing.

  At least however we can here at Obsolete Technology Tellye !  establish some basic principles to use as a starting point. There is a difference between the kind of picture quality defects that you would expect to find in a manufactured receiver compared to one made by a home restorer / constructor. 

A CRT manufactured receiver usually has only minor faults and one wants to'assess how well it compares with the products of other set - makers.

Todays trade, threw a rather different light on matters however. Briefly, we found that during CRT boom periods for the setmakers reliability increased whilst during periods of diminishing sales a fall in the standard of reliability became evident, so you will find excellent sets from the 70s/80s. I had tended to think that a boom meant an attitude of anything goes to get as many sets out to meet the demand, with consequent corner cutting and use of whatever alternative components could be got hold of if necessary. The overriding point seems to be however that in boom conditions with a seller's market prices can be maintained and quality standards kept up whilst in flat market conditions there is overwhelming pressure on prices and reliability tends to fall. It is difficult to be too sure about this since the worst trading period coincided with the era of dual standard analog TV sets which may eventually but not certainly inevitably less reliable than the single -standard chassis which preceeded and succeeded them. It would however tie up  about the comparative reliability of colour and monochrome sets, since the era of colour boom coincides with a very flat period in monochrome set production and sales, that in talking about reliability means overall dependability rather than initial statistics for unboxed set condition. 

That all said is very applicable to todays times, with completely different technically means, reality were unfair market conditions focibly applied to European firms by an elite which has only the will and target to destroy European eritage atall levels with the starting point destroying local economy.

It includes:

- A number of areas of law involving acts by one competitor or group of competitors which harm another in the field, and which may give rise to criminal offenses and civil causes of action.

- Trade libel, the spreading of false information about the quality or characteristics of a competitor's products, is prohibited at common law but still high present and unstopped.

- Various unfair business practices such as fraud, misrepresentation, and unconscionable contracts may be considered unfair competition, if they give one competitor an advantage over others expecially all from the so called ASIATIC MARKET.

Therefore:

All of todays apparates are literally absolute GARBAGE when new and resulting often broken when out of the box after purchase. Poor engineering, manufacturing and materials in the main part, combined with unfair massive import to Europe of such DUMP goods, at cheap prices in closed hard tight market (so they can be the only 2 3 competitor in foreign lands and all locals firms brought to death by taxations, difficulties at all levels) and sold with medium to high prices respect to initial build costs !!

For that there is NO comparable reliability between a CRT TV SET and any one of todays sets, which often are resulting in a SCAM mainly under the technological part, emerging from the first repair attempt !

......  And  in the end you will NEVER SEE a restoring of ANY of the Actual todays electronic GARBAGE !

R.I.P.  EUROPE !




It's made by MIVAR an Italian Brand no more active since 20/12/2013.


MIVAR is a Factory site in the near of Milan (italy) in a Industrial city conglomerate called Abbiate Grasso.

Founded in 1945 by Mr. Carlo Vichi class of 1923, The activity started in 1945 - in Milano, Via Ugo Tommei 5 street with fabrication of little radio apparates.

HISTORY OF MIVAR.

1945 - Milan, Via Ugo Tommei 5: Begin the activity assembling small radios.

1950 - Via Curtatone 12: developed with the construction of more direct major radio components fabricants.

1956 - 13 Street Strigelli: industrial production is manily targeted to first radio devices with frequency modulation (FM).

1958 - Via P. 30 Jordanians: TV become a reality, the industries is doubling his ACTIVITY, always in Milan, we build the first "real" plant with 400 employees.

1963 - Abbiategrasso, Via Dante 45: in the wake of decentralization and the rampant success of the television, building a facility that will become important in place 800 employees occupying between 1968-70.

1990 - Abbiategrasso Canal towpath: aware of the physiological importance that television plays in society? Modern, rich expertise and resources, we began construction of a factory area of ​​120,000 m? which covered 30.00o , for the viabilit with parking spaces and 60,000 park trees.

In origin the factory was brand named as Radio Var and indeed the tellye here in collection is internally marked as Radio VAR. After 1985 they were marked rightly MIVAR.
Today's activity is oriented in virtual production of LCD crap but with very low market penetration due to "unfair" asian competitors presence and a local governement which don't care about.

(You call it global market, I call it WORLD DESTRUCTION combined toghether with mass Afro scum crap Immigration (EUROPEAN INVASION) to obtain destruction on a large scale in all places and to help more and better the loose of all OUR workplaces and firms , lives, people).

 “If our buildings, our highways, and our railroads should be wrecked, we could rebuild them.

If our cities should be destroyed, out of the very ruins we could erect newer and greater ones.

Even if our armed might should be crushed, we could rear sons who would redeem our power.

Anyway Obsolete Technology Tellye will show even this model as a Time machine which looses nothing of the good tellyes ! ! !

Further Notes:

^ "MIVAR: tutto iniziò in via Tommei", articolo tratto dal sito quattronet.it Archiviato il 14 novembre 2011 in Internet Archive.^ [Maker], Mivar ; Milano from Audiphon to Trader, 703 pictures, 124 sc, su www.radiomuseum.org. URL consultato il 13 giugno 2018.^ NUOVO ASSALTO AL CARROZZONE REL - la Repubblica.it, in Archivio - la Repubblica.it. URL consultato l'11 gennaio 2018.^ LA MIVAR FA UTILI SENZA SPENDERE PER LA PUBBLICITA' - la Repubblica.it, in Archivio - la Repubblica.it. URL consultato l'11 gennaio 2018.^ MIVAR, MIRACOLO AD ABBIATEGRASSO - la Repubblica.it, in Archivio - la Repubblica.it. URL consultato l'11 gennaio 2018.^ Archivio Corriere della Sera, su archiviostorico.corriere.it. URL consultato l'11 gennaio 2018.^ Archivio Corriere della Sera, su archiviostorico.corriere.it. URL consultato l'11 gennaio 2018.^ notizia del sito Adnkronos del 4 maggio 2005 Archiviato il 19 ottobre 2006 in Internet Archive.^ JOB MILANO, in archive.is, 10 dicembre 2012. URL consultato l'11 gennaio 2018 (archiviato dall'url originale il 10 dicembre 2012).^ Mivar rilancia in Full Hd - Il Sole 24 ORE, su www.ilsole24ore.com. URL consultato l'11 gennaio 2018.^ (IT) Mivar In Crisi Ma Il Riscatto Avverrà Con I Led, su www.paid2write.org. URL consultato l'11 gennaio 2018.
MonrifNet, Televisori Mivar: fine dei programmi il 30 novembre - Il Giorno - Legnano, su www.ilgiorno.it. URL consultato l'11 gennaio 2018.
^ “La mia Mivar chiude, l’affitto gratis a chi assume 1200 italiani”, in Fanpage. URL consultato l'11 gennaio 2018.