A question about the circuitry of modern TVs

[basil lambri]

I am not a technician but I know that the old color TVs with vacuum tubes had something like 16 different circuits controlling the picture. That was reduced in later solid state TVs to 1 circuit controlling the 3 guns. Zenith for example had about 8 modules in their Chromacolor solid state TV sets. Then they reduced it to 3 modules in their System 3 sets and then to 2 modules.

My question is doesn't this big reduction in circuits affect the performance of the newer solid state sets compared to the good performance of the older TVs?

[maxhifi]

Newer tvs are more electronically complex and contain more components than old ones. They are just miniaturized due to advances in technology, and therefore all circuity can be placed on one or two boards, instead of a large full chassis. similar to how my blackberry probably is more powerful than a 1960s computer occupying a whole room.

[zenith2134]

Hi-
I don't equate overall reliability or quality with number of boards in a set.

Now, a lot of old tubed tv's were circuitboard-less, and used point-to-point wiring instead. That, IMO, is a substantial point since the p-t-p's have the potential to be much more reliable when used with vacuum tubes.

[basil lambri]

Originally Posted by maxhifi

Newer tvs are more electronically complex and contain more components than old ones. They are just miniaturized due to advances in technology, and therefore all circuity can be placed on one or two boards, instead of a large full chassis. similar to how my blackberry probably is more powerful than a 1960s computer occupying a whole room.

Yes, what I really had in mind when I was talking about newer solid state TVs were the first solid state TVs that came out in the 1970s and '80s. I am wondering if those were inferior to vacuum tube sets because they had drastically reduced circuitry when the tubed sets had so many circuits controlling the picture.
Of course the TVs that are made now have microchips which are very complex.

[maxhifi]

the first solid state tvs were similar in circuit complexity and features with the tube sets they replaced, or maybe even had more active elements, and designs became progressively more complex, adding better features and performance as technology progressed.

Even early solid state sets are more stable, require less adjustment,use less power, and offer better performance than most tube sets. One area you can really see this is color bars.. My tube sets have some overlap between them, my ss sets have crisp deliniation

[kx250rider]

Originally Posted by basil lambri

I am not a technician but I know that the old color TVs with vacuum tubes had something like 16 different circuits controlling the picture. That was reduced in later solid state TVs to 1 circuit controlling the 3 guns. Zenith for example had about 8 modules in their Chromacolor solid state TV sets. Then they reduced it to 3 modules in their System 3 sets and then to 2 modules.

My question is doesn't this big reduction in circuits affect the performance of the newer solid state sets compared to the good performance of the older TVs?

Actually, the circuitry increased in number of circuits, but the size of the parts got smaller. The same basic necessary circuits (as thought of in a block diagram), are the same from 1937 (and for color 1954) until the end of analog CRT TV sets. A Zenith Chromacolor II has the same basic parts as the Sys III, but for instance, the Chro II has the B+ power supply, horizontal output and flyback and tripler on the mainframe chassis, and on small modules were the horizontal oscillator (9-90), the vertical oscillator & outputs (9-147), whereas the later Sys III has it all on the 9-160 board. A 1990s Zenith TV has it all on one small board, with one chip containing basically the whole front end of the TV, and another containing chroma, video, horizontal & vertical oscillators, and a myriad of other stuff. But if you trace it all out, the circuit is basically on the same original principles as 50 years prior. It's still three color signals driving three cathodes in the CRT, and the tuner is still an RF amplifier, a detector, and frequency selection by swapping coils in old click-tuners, and by changing varactor voltage in electronic tuners. There is still a 3.58mc oscillator crystal for the chroma oscillator, and keyed burst, and either digital or analog circuitry for demodulation, bandpass, etc. Maybe an analogy would be that an elephant and a chihuahua are both basically the same biological machine; using the same support resources, mating, and producing live offspring.

Charles

[old_coot88]

Originally Posted by kx250rider

...Maybe an analogy would be that an elephant and a chihuahua are both basically the same biological machine; using the same support resources, mating, and producing live offspring.

Gadzooks!!What do their offspring look like? A chupacabra with a trunk?

[Jeffhs]

What amazes me about today's HDTVs is how they can be made so slim. I have an Insignia (rebadged Osram Sylvania) 19" flat-panel set that is probably only an inch thick (if that much) from front to back. (I was amazed how much smaller that set is than the RCA CTC185 it replaced.) I was reading somewhere that the use of LEDs, rather than cold-cathode fluorescent lamps (CCFLs), for backlighting the screen allows the manufacturers of these sets to make them much thinner than sets using the larger lamps, and certainly thinner than the first HDTVs with incandescent backlights. There is no need to worry, either, about replacing burned-out lamps in the newer sets, as LEDs can last a very long time before requiring replacement. I read on Zenith/LG's website recently that their flat panel TVs will last up to 60,000 hours before dimming to half brightness, which equates to over 20 years of life if the set is used eight hours a day. I wonder if any other FP available today can match that.

[old_coot88]

I dunno, but from what little i've seen of the flat panel stuff gone bad right off the bat, the primary failure mode is electrolytics, not the display panel itself.

[andy]

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