NORDMENDE SPECTRA SK2-COLOR UC7732 YEAR 1976.

The NORDMENDE SPECTRA SK2-COLOR UC7732 is a 22 inches color television.

Was featuring first time the PHILIPS 20AX CRT TUBE, The PHILIPS 20AX system was introduced in Europe in 1975 as the first self converging picture tube/deflection coil, combination for 110° degree deflection and screen sizes up to 26". The system is based on the automatic convergence principle discovered by Haantjes and Lubben of Philips Research Laboratory more than 20 years ago. It makes use of an in-line gun array in conjunction with a specially designed saddle type deflection coil. Residual small tolerance errors are compensated by a simple dynamic four-pole system. The tube is 2 cm shorter than conventional 110° Degree tubes and has a standard 36.5 mm neck in order to obtain good color selection. A slotted mask is used in combination with a stripe-structure screen. Picture sharpness is ensured by an astigmatic electron gun and the SK2-COLOR series, and Ultrasonic remote control with manual tuning search system with potentiometers.

The new tube, to be known as the 20AX, has been developed by PHILIPS in conjunction with the parent Philips / Mullard organisation and will be produced by several Philips subsidiary companies on the Continent as well as by PHILIPS in the UK. PHILIPS envisage quantity production of the tube by 1976, mainly for export at first, with large-scale production for UK set - makers starting in 1977. The tube has been developed as "probably the final phase in the design of the 110° shadowmask tube". Its main features are the use of three guns mounted horizontally in line, the use of a shadow - mask with slots instead of circular holes, and a screen with the phosphors deposited in vertical stripes instead of as a pattern of dot triads. It seems therefore that the days of the present delta gun shadowmask tube are now numbered, though considerable production will have to continue for many years to provide replacement tubes for the millions of colour sets already in use. So far as the viewer is concerned however it is important to appreciate the time scale involved (see above) and the reasons for the development of the new tube. There is nothing wrong with the type of shadow - mask tube we have known since the beginning of colour TV: it is able to provide superb pictures. But in its 110° form it does require rather a lot of scan/convergence correction circuitry. If this can be reduced by means of an alternative approach

as with the 20AX tube  considerable benefits in set production and servicing will be obtained. This has been the aim behind the development of the new tube, and the demonstration tube we have seen operating with its associated deflection yoke and circuitry gave a picture every bit as good as we have come to expect from the present "conventional" approach to colour tube design. There are now four colour tubes with in -line guns, the Sony Trinitron (the first to come along), the RCA /Mazda PIL tube, the Toshiba RIS tube and now the PHILIPS 20AX. It is interesting to compare them. The Trinitron is a 90° narrow neck (29mm) tube. It differs from the others in using an aperture grill (slits from top to bottom) instead of a mask behind the screen to shadow the beams and a tube face which is substantially flat in the vertical plane. On the domestic market it is used exclusively in Sony sets and certainly represented a break through in simplifying the convergence circuitry and setting up adjustments required. The Toshiba RIS (rectangular flare, in-line guns, slotted shadowmask) tube has now turned up in the UK in the recently introduced 18in. Sharp Model C1831H. Its most distinctive feature is the rectangu- lar instead of conical tube flare and the rectangular semi -toroidal scanning yoke which is used with this. It is a 110° thick neck (36mm) tube. The convergence arrangements are fairly simple. The most interesting comparisons however are between the PI tube and the 20AX. The first is a 90° tube of the narrow neck variety and features a toroidal yoke which is cemented to the tube- thus if either is faulty the entire tube/yoke assembly must be replaced. The great advantage is that no dynamic convergence adjustments or circuitry are required. It is at present limited to sizes up to 20in. and the designers say that it is not intended as a successor to the standard shadowmask tube above this size. Its depth compares with 110° tubes because of the simplified gun structure used. The PHILIPS 20AX tube differs from it in several respects. First it is basically a 110° tube which can be produced in a whole range of sizes production of 18, 22 and 26in. versions is proposed so that set  makers can use it with a single chassis for models of various sizes. Secondly it uses saddlewound deflection coils which are separate from though accurately aligned with the tube. And thirdly it is a thick neck tube. Unlike the PI tube in which all the gun electrodes except the cathodes are common to all guns the electrodes of each gun in the 20AX are separately available at the base. This means that in addition to RGB drive to the cathodes the grids are available for blanking and beam limiting and the first anodes for background control setting in the normal manner. In fact PHILIPS emphasised that the new tube is entirely compatible with existing colour set techniques  though the whole convergence system is greatly simplified. The basic idea behind these in line gun, slotted mask tubes is that by mounting the guns horizontally in line the convergence errors are confined to the horizontal plane and by applying an astigmatic deflection field these errors are cancelled. This means that a fair amount of cunning in the design of the deflection yoke is required. A saddlewound yoke is more efficient than a toroidal yoke since the deflection fields are totally enclosed.

 In comparison to current 110° PHILIPS tubes the 20AX requires much the same horizontal deflection power but about twice the vertical deflection power (which can be obtained without trouble from modern semiconductor devices). The use of a separate yoke with a tube of this type means that some dynamic convergence controls are still necessary, in order to match the assemblies. PHILIPS refer to these as "tolerance adjustments" rather than "dynamic convergence controls". About seven are required at present though further work is being done on this and by the time sets with the new tube appear we can expect some reduction. A single pincushion transductor is required instead of the two needed with 110° shadowmask tubes of the present variety. In comparison the PIL  tube requires no dynamic convergence adjustments, only some simple tube neck magnets for static setting up. It is a little less efficient however because of the type of yoke employed. Whatever else happens there is no doubt that the vast majority of colour tubes fitted to TVC sets come 1977 will be of the in line gun, slotted mask, vertical phosphor stripe variety. Two further points made by PHILIPS at their demonstration : first, this type of tube requires less degaussing so that there are worthwhile savings in the amount of copper required for the degaussing coils: secondly their new tube, and in fact all PHILIPS monochrome tubes and shortly their colour tubes as well, will incorporate "instant on" guns which come into operation about  five seconds after the set is switched on instead of the 30 seconds or more taken by present tubes. This instant on feature is based on a new heater/cathode assembly in which the use of mica insulators has been avoided. 

Meanwhile we understand that in addition to RCA and, in the UK, Mazda, ITT and Videocolor SA are to produce PIL tubes. Whilst congratulations all round was appropriate on the successful development of these  tubes it does seem a pity that was about to enter for the first time an era of non compatible colour c.r.t.s.

This model series was a luxus model and was introducing in 1976 the SK2 series which was standing for "System Kalt"
named as Cool system referring to low chassis temperature.
Was more related to the RGB OUTPUT amplifiers than the line / horizontal output wich is realized with THYRISTORS and for that it runs warm as any Thyristor line output stage.

- Horizontal Beam Deflection  and high voltage generating circuits realized with Thyristors circuits.

The massive demand for colour television receivers in Europe/Germany in the 70's  brought about an influx of sets from the continent. Many of these use the thin -neck (29mm) type of 110° shadowmask tube and the Philips 20AX CRT Tube, plus the already Delta Gun CRT . 

Scanning of these tubes is accomplished by means of a toroidally wound deflection yoke (conventional 90° and thick -neck 110° tubes operate with saddle -wound deflection coils). The inductance of a toroidal yoke is very much less than that of a saddle -wound yoke, thus higher scan currents are required. The deflection current necessary for the line scan is about 12A peak -to -peak. This could be provided by a transistor line output stage but a current step-up transformer, which is bulky and both difficult and costly to manufacture, would be required. 

An entirely different approach, pioneered by RCA in America and developed by them and by ITT (SEL) in Germany, is the thyristor line output stage. In this system the scanning current is provided via two thyristors and two switching diodes which due to their characteristics can supply the deflection yoke without a step-up transformer (a small transformer is still required to obtain the input voltage pulse for the e.h.t. tripler). The purpose of this article is to explain the basic operation of such circuits. The thyristor line output circuit offers high reliability since all switching occurs at zero current level. C.R.T. flashovers, which can produce high current surges (up to 60A), have no detrimental effects on the switching diodes or thyristors since the forward voltage drop across these devices is small and the duration of the current pulses short. If a surge limiting resistor is pro- vided in the tube's final anode circuit the peak voltages produced by flashovers seldom exceed the normal repetitive circuit voltages by more than 50-100V. This is well within the device ratings.  It's a very good system to use where the line scan coils require large peak currents with only a moderate flyback voltage  an intrinsic characteristic of toroidally wound deflection coils. The basic thyristor line output stage arrangement used in all these chassis is shown in Fig. 1
it was originally devised by RCA. Many sets fitted with 110°, narrow -neck delta -gun tubes used a thyristor line output stage - for example those in the Grundig and Saba ranges and the Finlux Peacock , Indesit, Siemens, Salora, Metz, Nordmende, Blaupunkt, ITT, Seleco, REX, Mivar, Emerson, Brionvega, Loewe, Galaxi, Stern, Zanussi, Wega, Philco. The circuit continued to find favour in earlier chassis designed for use with in -line gun tubes, examples being found in the Grundig and Korting ranges - also,  Indesit, Siemens, Salora, Metz, Nordmende, Blaupunkt, ITT, Seleco, REX, Mivar, Emerson, Brionvega, Loewe, Galaxi, Stern, Zanussi, Wega, Philco the Rediffusion Mk. III chassis. Deflection currents of up to 13A peak -to -peak are commonly encountered with 110° tubes, with a flyback voltage of only some 600V peak  to peak. The total energy requirement is of the order of 6mJ, which is 50 per cent higher than modern 110° tubes of the 30AX and S4 variety with their saddle -wound line scan coils.   The only problem with this type of circuit is the large amount of energy that shuttles back and forth at line frequency. This places a heavy stress on certain components. Circuit losses produce quite high temperatures, which are concentrated at certain points, in particular the commutating combi coil. This leads to deterioration of the soldered joints around the coil, a common cause of failure. This can have a cumulative effect, a high resistance joint increasing the local heating until the joint becomes well and truly dry -a classic symptom with some Grundig / Emerson sets. The wound components themselves can be a source of trouble, due to losses - particularly the combi coil and the regulating transductor. Later chassis are less prone to this sort of thing, partly because of the use of later generation, higher efficiency yokes but mainly due to more generous and better design of the wound components. The ideal dielectric for use in the tuning capacitors is polypropylene (either metalised or film). It's a truly won- derful dielectric - very stable, with very small losses, and capable of operation at high frequencies and elevated temperatures. It's also nowadays reasonably inexpensive. Unfortunately many earlier chassis of this type used polyester capacitors, and it's no surprise that they were inclined to give up. When replacing the tuning capacitors in a thyristor line output stage it's essential to use polypropylene types -a good range of axial components with values ranging from 0.001µF to 047µF is available from RS Components, enabling even non-standard values to be made up from an appropriate combination. Using polypropylene capacitors in place of polyester ones will not only ensure capacitor reliability but will also lower the stress on other components by reducing the circuit losses (and hence power consumption).
       Numerous circuit designs for completely transistorized television receivers either have been incorporated in commercially available receivers or have been described in detail in various technical publications. One of the most troublesome areas in such transistor receivers, from the point of View of reliability and economy, lies in the horizontal deflection circuits.
       As an attempt to avoid the voltage and current limitations of transistor deflection circuits, a number of circuits have been proposed utilizing the silicon controlled rectifier (SCR), a semiconductor device capable of handling substantially higher currents and voltages than transistors.
       The circuit utilizes two bi-directionally conductive switching means which serve respectively as trace and commutating switches. Particularly, each of the switching means comprises the parallel combination of a silicon controlled rectifier (SCR) and a diode. The commutating switch is triggered on shortly before the desired beginning of retrace and, in conjunction with a resonant commutating circuit having an inductor and two capacitors, serves to turn off the trace switch to initiate retrace. The commutating circuit is also arranged to turn oft the commutating SCR before the end of retrace. 

(Sa example the only THYRISTORS Horizontal Deflection stages running almost really cool was that in GRUNDIG GSC600 AND GRUNDIG GSC700 CHASSIS which you can see Here at Obsolete technology Tellye museum [ search for it here ] ).
The set is a first in featuring  a new set of PAL decoder chips which has been introduced by Siemens, the TDA2560/TDA2522/TDA2530. The first two of these second -source the latest Philips/Mullard decoder i.c.s, with the TDA2560 as luminance and chrominance signal amplifier and the TDA2522 as the reference oscillator/chrominance demodulator. Interesting features of this set up are the fact that the burst signal passes through the chrominance delay line and the fact that the reference oscillator operates at 8.86MHz, a digital divider providing exactly 90° phase displaced 4.43MHz outputs without the need for a phase shift coil. The first UK produced chassis to use these i.c.s is the Tandberg CTV3, the larger UK setmakers staying for the time being with the TBA560C/TBA540/TCA800 combination. The third i.c. from Siemens is the TDA2530 which supersedes the well known TBA530 luminance/colour-difference signal matrix- ing i.c. The TDA2530 contains a negative feedback driver amplifier and internal clamping in addition to the matrixing network.
The set is build with a Modular chassis design because as modern television receivers become more complex the problem of repairing the receiver becomes more difficult. As the number of components used in the television receiver increases the susceptibility to breakdown increases and it becomes more difficult to replace defective components as they are more closely spaced. The problem has become even more complicated with the increasing number of color television receivers in use. A color television receiver has a larger number of circuits of a higher degree of complexity than the black and white receiver and further a more highly trained serviceman is required to properly service the color television receiver.
Fortunately for the service problem to date, most failures occur in the vacuum tubes used in the television receivers. A faulty or inoperative vacuum tube is relatively easy to find and replace. However, where the television receiver malfunction is caused by the failure of other components, such as resistors, capacitors or inductors, it is harder to isolate the defective component and a higher degree of skill on the part of the serviceman is required.
Even with the great majority of the color television receiver malfunctions being of the "easy to find and repair" type proper servicing of color sets has been difficult to obtain due to the shortage of trained serviceman.
At the present time advances in the state of the semiconductor art have led to the increasing use of transistors in color television receivers. The receiver described in this application has only two tubes, the picture tube and the high voltage rectifier tube, all the other active components in the receiver being semiconductors.
One important characteristic of a semiconductor device is its extreme reliability in comparison with the vacuum tube. The number of transistor and integrated circuit failures in the television receiver will be very low in comparison with the failures of other components, the reverse of what is true in present day color television receivers. Thus most failures in future television receivers will be of the hard to service type and will require more highly qualified servicemen.
The primary symptoms of a television receiver malfunction are shown on the picture tube of the television receiver while the components causing the malfunction are located within the cabinet. Also many adjustments to the receiver require the serviceman to observe the screen. Thus the serviceman must use unsatisfactory mirror arrangements to remove the electronic chassis from the cabinet, usually a very difficult task. Further many components are "buried" in a maze of circuitry and other components so that they are difficult to remove and replace without damage to other components in the receiver.
Repairing a modern color television receiver often requires that the receiver be removed from the home and carried to a repair shop where it may remain for many weeks. This is an expensive undertaking since most receivers are bulky and heavy enough to require at least two persons to carry them. Further, two trips must be made to the home, one to pick up the receiver and one to deliver it. For these reasons, the cost of maintaining the color television receiver in operating condition often exceeds the initial cost of the receiver and is an important factor in determining whether a receiver will be purchased.
Therefore, the object of this invention is to provide a transistorized color television receiver in which the main electronic chassis is easily accessible for maintenance and adjustment. Another object of this invention is to provide a transistorized color television receiver in which the electronic circuits are divided into a plurality of modules with the modules easily removable for service and maintenance. The main electronic chassis is slidably mounted within the cabinet so that it may be withdrawn, in the same manner as a drawer, to expose the electronic circuitry therein for maintenance and adjustment from the rear closure panel after easy removal. Another aspect is the capability to be serviced at eventually the home of the owner.

It was even introducing the 20AX CRT TUBE (PHILIPS) in models from 26 to 22 Inches but in few it was replaced by the VIDEOCOLOR P.I.L.

The set has even front led lamps to show the remote controls during calling via US remote and a front display showing program numbers.

This here shown is a heavy used set for almost 26 Years by the original owner combined with all day permanent power on.



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




Nordmende was a manufacturer of entertainment electronics based in Bremen, Germany.
The original company, Radio H. Mende & Co, was founded in 1923 by Otto Hermann Mende (1885-1940) in Dresden. Following the destruction of the plant during the bombing raids in 1945, Martin Mende (the founder's son) created a new company in Bremen in 1947, in a former Focke-Wulf plant, under the name North German Mende Broadcast GmbH. The name was subsequently changed to Nordmende: subsequently the company became one of the prominent German manufacturers of radios, televisions, tape recorders and record players in the 1950s and 1960s.
In the 1970s, Nordmende televisions were renowned for their innovative chassis, and for the rigorous testing and quality control of their finished products. Both created high costs, however, which soon proved a competitive disadvantage when the price of colour televisions began to plunge.
In 1969, Mende's sons took over the company, and in 1977 a majority shareholding was sold to the French Thomson Brandt company and the chassis remains the original NordMende until CHASSIS F9. The following year, the family sold their remaining shares to Thomson. In the 1980s, the factories in Bremen were closed, Nordmende becoming purely a Thomson trademark (Starting from chassis F10 F11 they're all THOMSON).








In the 1990s, the name Nordmende was used with decreasing frequency, and it eventually disappeared in favour of the Thomson name. In 2005 Videocon Group acquired all cathode ray tube activities from Thomson. This led to the creation of VDC Technologies, which manufactures TV sets using the Nordmende brand under licence from Thomson.
The Nordmende brand name was relaunched in Ireland in September 2008 by the KAL Group. Although Nordmende was well known for its televisions throughout Ireland during the 1970s and 1980s, the company bought the rights to the name and launched a range of white goods including fridges, freezers, washing machines, and dishwashers, alongside a revamped range of flat-screen TVs and stereos.

Weblinks:

 Commons: Nordmende – Sammlung von Bildern, Videos und Audiodateien
Tote Marke NORDMENDE – Verblasster Stolz. Artikel im Manager-Magazin
Ein neues Programm. Artikel in der Zeit
Fernseher: Inder produzieren neue Nordmende. Artikel bei itespresso.de
Videocon produziert Plasmaschirme für Nordmende. Artikel im pressetext.de

Einzelnachweise

Spectra Color Studio und Spectra SK2 Color de Luxe Studio auf radiomuseum.org
Marke Nordmende mit Digital- und Internetradios zurück, teltarif.de, Artikel vom 2. September 2017.


Company profile. Phillar, archiviert vom Original am 6. März 2008; abgerufen am 26. April 2013 (englisch).


Broschüre – Sprachmanager24. Abgerufen am 5. Januar 2015.