ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades A question for Paul

Guys,
Is it just me, or is TV manufacture down to a formula these days? (just like music)
It may have been this way for years going by the chassis' I've seen.
Power supply on the rear left (looking from the back), audio and video in the centre.
LOPT and EHT to the right?.
Just wondering.

Trumpy, I think you're absolutely correct, and it goes to show how 'conditioned' I am, the fact I never queried why.

Part of the reason for the power supply section being on the left when viewed from the back may be because people expect the controls (including switches) to be on the right, and things got fitted in round that.

Interesting observation...that chassis layout has been around since the 50's. In fact I'm trying hard to think of any set, valve or solid state that doesn't have the EHT bits on the right rear corner. I think we can say that the reason for EHT and power transformers being along the back is simply to allow less of a gap between the PCB or chassis and the bottom of the CRT. Being along the edge is obviously better from a weight distribution point of view, but why is the EHT always on the right? Interesting question. As far as a 'formula' for the electrical design there aren't any radical designs these days....like the Sony seperate EHT and line output stages of the 70's. Philips' combined switchmode PSU and line output stage they played around with in the 80's, and who remembers Sony with their unique PAL decoder to avoid paying royalties to Telefunken? Instead of reversing the R-Y every second line, it stored and released the R-Y from the previous non inverting line instead. It could be said that the colour definition was therefore effectively halved. Also, a manual phase or hue adjustment was required like NTSC sets. Nevertheless, it did work very well. And of course was RCA's thyristor line output which allowed the first fully solid state colour sets. Today's robot built sets coming from one or two Asian factories and supplying the world market are in comparison quite boring and predictable.

Ahh so it's not just me that has picked this up?.
I'm sort of thinking that maybe it has something to do with cooling.
As in, keeping the EHT gear and the power transformer away from the tube would help keep the radiated heat (and magnetic fields) away from the degaussing coils and the yoke coils?.

Hmmm..... You've got me thinking now. I'll have to dig out some old service sheets tonight see if I can come up with anything.

Murphy was a British manufacturer noted for often coming up with "odd" ways of doing things, so those sets might be worth a look.

The controls down the right-hand side convention may well have contributed to the layout. For example, once varicap tuning came along the channel selector could have been placed almost anywhere in relation to the actual tuner, but before then the tuner was normally fitted right behind the controls, for obvious reasons. With the tuner(s) on the left, as viewed from behind, it would then make sense for the I.F. stages to be close by, and so on, down the chain.


Again, I'm pretty sure some of the earlier Murphy sets (possibly others too) did this in the early 50s. The EHT in some of those could be quite lethal -- Literally.


I don't remember that one. What sort of time period was this?

By the time you add the delay line to store the non-inverted R-Y, it seems you might just as well have gone with a conventional PAL decoder, but I suppose it depended how much they would have been saving in fees.

I don't know about Australian models as color didn't arrive there until later, but some of the earlier color receivers in Britain were the PAL-S type. They had the R-Y inversion synched to the swinging color burst as usual, but no delay line, so they just relied on a visual averaging between lines to cancel out any phase errors.