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The most popular 70's colour set

 
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Re: The most popular 70's colour set

Post by TVJON74 » Tue Jan 05, 2016 6:28 pm

Hi Till,
That's an official mod from B&O on one of their service bulletin's.
I have just checked the PCB layouts in the manual and pin 6 is not used in the 3400.
It does however go in to details for the 3000, 3200 and 2600 series sets to disconnect pin 6 and change the heater wiring due to internal connections of pin 6&8 on PL802 as you correctly point out.
But I agree if the correct part is available use the correct part.

 
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Re: The most popular 70's colour set

Post by Till Eulenspiegel » Tue Jan 05, 2016 9:05 pm

Correction to my last post. I mentioned that the 12BH7 was the predecessor to the 12HG7, I should wrote 12BY7.
From the Radiomuseum: http://www.radiomuseum.org/tubes/tube_12by7a.html
The 12BH7 is a double-triode.
When did B&O introduce their first colour TV set?

Till Eulenspiegel.

 
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Re: The most popular 70's colour set

Post by ntscuser » Tue Jan 05, 2016 10:49 pm

Till Eulenspiegel wrote:When did B&O introduce their first colour TV set?


The single-standard 3000SJ was introduced in the UK some time in 1968. It may have been available on the continent the previous year.

 
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Re: The most popular 70's colour set

Post by Till Eulenspiegel » Tue Jan 05, 2016 11:11 pm

If the 1970/71 Radio and Television servicing book is to hand, the circuit diagram of the B&O 3000 can be found in the pages 16 to 31.
Strangely, although the set has a series heater chain for the timebase valves, the designer opted for ECL84 6.3 volt heater triode-pentodes for the colour difference amplifiers. Note the designation for the EB91, EAA91.

It's a thoroughly well engineered receiver. I'd imagine the pictures are excellent.

Till Eulenspiegel.

 
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Re: The most popular 70's colour set

Post by Cathovisor » Wed Jan 06, 2016 12:14 am

I was given one of those in about 1988 or so. Sadly, it sat unattended until one day, I decided that it was really rather too big and complicated to replace the Telefunken we then owned and I broke it up. I still remember the multi-band tuner, the proper tone controls, and dispatching the tube with the aid of the clothes prop.

Such a shame really - I remember discussing it with my colleagues at the time and they said the likeness to professional practice in all its engineering was astonishing. However, hindsight is the most beautiful sight in the world... :cch

Sad thing is, I doubt I'll ever see one again.

 
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Re: The most popular 70's colour set

Post by Studio263 » Wed Jan 06, 2016 8:51 am

Till Eulenspiegel wrote:
Strangely, although the set has a series heater chain for the timebase valves, the designer opted for ECL84 6.3 volt heater triode-pentodes for the colour difference amplifiers. Note the designation for the EB91, EAA91.


This was, I expect, because the designer was running out of volts for the heater chain. This set was expected to work properly on 220V and has 18 valves (although the specification says 14, they don't count the EAA 91s for some reason) including PL509, PL508, PL504, PY500A, PY88, PL84, PCC85, PCF802 and ECC82 on the series chain. The rest are GY501 (fed from the EHT transformer) and 8 more on the tiny CDA panel, 3 ECL84s (one triode not used and the two others connected in parallel for blanking), one 12HG7 and four EAA91s. It gets hot up there...

These sets were a clever design, in particular EW correction was added by modulating the drive to the line output valve (they had a seperate EHT generator so they could get away with that). The waveform comes from the frame timebase and is derrived by sitting the whole circuit on a low value resistor to obtain a ground referenced frame current waveform, a strange idea but it works. Also, EHT regulation was performed in a similar way in the relevant stage, using a PCC85 as the controlling element - no nasty PD500! The average level was monitored by resistors at the earthy end of the overwind whist fast changes were sensed by looking at the signals capacitively coupled into the braiding around the EHT cable. I can't remember how much EHT current these could produce but I think it was something like 12.5mA, far more than any other colour set of the era (or since, I hope!) with near instant regulation. Needless to say the picture is perfectly square and rock solid. The 2600 and 3200 used the same chassis, 3000s are scarce but there are still a decent number of 2600s around. The 3000 was a hard sell to begin with as it was the first single standard set you could buy in the UK, it had an integrated UHF / VHF tuner but was 625 line only. In 1968 this relegated them to BBC2 only but the situation soon improved. The picture quality sold them in any case. The 3000 was 25" with an A63-11X tube, a true "first generation" design. The 3200 was the same thing but with tidied up styling and an A66-120X. These were both cabinet sets with doors on the front, the 2600 was a table model with an A56-120X in it. The quirk here was that the convergence panel was underneath, so unless you had the (optional) stand you couldn't reach it! They had a 2800 model on the continent too, which was a 22" set in a fancier cabinet (the 2600 looks rather like a huge Sony KV-1320UB). They had a 22" version of the 3400 too called the 3100 but the trouble with all the 22" B&O hybrids was that they weren't that much smaller than the bigger ones as the cabinet sized was dictated by the dimensions of the chassis, not the tube.

The left hand side of things is much like the 3400, but they got rid of the EAA91s and put silly little green diodes in instead which played up in the tube ever flashed over. The decoder is the same, apart from a DL50 delay line which replaced the DL1 of the earliest sets. There were changes on the IF panel as well, partly in how the 12V line is derrived. In the 3400 it is obtained from the electronically stabilised 32V supply dropped by a zener diode and a potential divider, the top half of which includes the heater of the 12HG7.

I had a 2600 with originally came from an advertisment in 'Television'. There was quite a lot wrong with it when I got it but it worked superbly once it was fixed. It was recommended in an earlier issue that the EHT be reduced to 22.5 kV to extend the life of the overwind so I di that, along with their recommended method of setting up the width controls to reduce the heat output of one of the big coils. These sets tend to cook up the wiring at the top of the EHT box, true to form mine was burnt to a crisp! The worst offender is the small screened lead that carries the drive to one of the valves, this casues all sorts or strange problems if you don't know about it. Glyn in Wales has the set now, I needed to make some room so I kept the 3400 which is smaller, despite being a 26" set.

 
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Re: The most popular 70's colour set

Post by Till Eulenspiegel » Wed Jan 06, 2016 12:46 pm

The B&O line output stage employs a PL504, a valve with modest power compared with the PL509. I'd guess the deflection power requirement for a 90 degree colour CRT operating at 25KV is about the same as a 110 degree mono CRT operating at 20KV.
The choice of output valve for the EHT generator is dictated by the demands from the EHT, 25KV X 1mA = 25watts!

I note that the wound components were sourced from Philips. Were these standard off the shelf components or specifically made for B&O?

Till Eulenspiegel.

 
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Re: The most popular 70's colour set

Post by Studio263 » Thu Jan 07, 2016 8:29 am

The line output and EHT transformers were made by Philips but I don't know if any other sets used the same ones, I doubt it as there seem to be lots of extra windings on both to cater for the 3000's quirks. The monochrome Beovision 1400 range is the same; it uses a similar LOPT to the ITT VC100 (?, the 20" hybrid one with the little flip-down PCB in the bottom of the cabinet) but there are extra windings for the line gated AGC system, I had to add these to an unused part of the core when the transformer "went" in mine.

The 3000 series sets were considered complicated here but they are fairly typical of continental luxury set practice at the time, have a look at Marcel's TV Museum site to see some examples. B&O were unusual in being able to sell this type of set here, the rest didn't bother or produced cut-down budget models for the UK market. Philips did at least try with the K70, K80 and K12, much better sets all than their UK equivalents. Sets that would have been considered exotic here, like the Grundig 6010, were fairly restrained by the standards of their home market.

I've been looking again at the Sony KV-1800UB, which like the Beovision 3400 first appeared in 1972. Although a bit gawky in appearance this was a fine piece of engineering, featuring what I think was the largest in-line type tube then in production and a fascinating line output stage / EHT generator section. Seperate stages were used but to keep them in sync the line stage was driven from a winding on the EHT transformer. EHT regulation was achieved by sensing the current at the bottom end of the overwind with the regulator itself in series with the emitter circuit of the EHT generator output transistor. Width and EW control was acheived with a series voltage regualtor which fed the line output transformer / transistor, this modulated the supply to the stage wit the appropriate waveforms to acheive the desired correction. All this lot was fed from a stabilised 110V supply derrieved from an autotransformer and a simple linear regualtor, the distribution of the loading, the low operating temperature and the high quality of the components ensured supreme reliability (10uF 160V start up capacitor and indifferent tube life aside...). Why they put a rotary UHF tuner on it is anyone's guess though.

 
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Re: The most popular 70's colour set

Post by hamid_1 » Fri Jan 08, 2016 12:27 am

Studio263 wrote:I've been looking again at the Sony KV-1800UB, which like the Beovision 3400 first appeared in 1972 ... Why they put a rotary UHF tuner on it is anyone's guess though.

I reckon it's because Sony's first colour TV exports were aimed at the North American market, where rotary tuners were the norm. Over there, TV stations are issued with a 4-letter callsign (beginning with W or K in the USA and C in Canada) and a VHF or UHF channel number. They announce their callsign and channel number regularly, for example "This is WUTV Channel 29 Buffalo New York". Over the years, audiences became familiar with the channel numbers of their local stations and simply twirled their rotary tuners around to them without any difficulty.

Over here, TV stations were regional or national. Preset tuning became the norm after the move to UHF. It was not practical for Britain's colour TV stations to announce their UHF channel numbers since they differed, even in the same region. People generally didn't get familiar with the channel numbers in their area and therefore found rotary tuners awkward to use.

Sony's first colour TVs in the UK seemed to have something in common with their US models: the cabinet styling, the rotary tuner, the colour decoder having a tint control like NTSC sets. The Mk.1 KV-1320UB ran on 110 volts internally - same as the US - with a stepdown transformer added for the UK. I suppose this enabled them to bring products to market quickly, without major redesigning, and thus gain a foothold. But Sony soon learned what Britain wanted. Rotary tuners were replaced by presets and proper PAL decoders were used in subsequent models.

 
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Re: The most popular 70's colour set

Post by Terrykc » Fri Jan 08, 2016 12:42 pm

hamid_1 wrote: ... People generally didn't get familiar with the channel numbers in their area and therefore found rotary tuners awkward to use ...
Earlier dual standard set owners probably didn't know that BBC2 was, for example, on channel 33 but were probably accustomed to the dial indicating somewhere in the 30 - 35 range, so could easily restore the correct tuning if someone fiddled with it.

However, I doubt if anybody outside the TV trade (other than an enthusiast) knew what all the channel allocations were in their area when 3-channel 625-line transmissions appeared and there was no logic to which programme appeared where.

Possibly, if the programme sequence had been BBC1 - BBC2 - ITV, to be followed later by Channel 4 - I don't think that any transmitter followed this sequence! - the public in general might have accepted the rotary tuner for much longer.

However, after Bush introduced 'Bush button' tuning with the TV85 series, UK users had had around 11 years experience of instantaneous programme selection before 3-channel UHF transmissions started in late 1969 and, once you've given the public something that they like it is virtually impossible to take it away from them!

 
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Re: The most popular 70's colour set

Post by colly0410 » Fri Jan 08, 2016 1:44 pm

My Mother had an 18 inches Sony & she never really got used to the rotary tuner. I'd go to visit & there'd be a snowy picture on it, I'd look at the tuner & it'd be in the 40's so tuned to Sutton Coldfield. I explained to her loads of times it needs to be in the 20's for the Nottingham (Kimberley) transmitter that you could see in the distance, I even wrote in down for her but she'd lose the note. When she had a video she'd leave the TV on ch36 & use the video remote control to change channel..

 
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Re: The most popular 70's colour set

Post by Paul_RK » Fri Jan 08, 2016 5:06 pm

hamid_1 wrote: People generally didn't get familiar with the channel numbers in their area and therefore found rotary tuners awkward to use...

I'm not sure that would have helped. Most people were only regularly using one TV, and my memory of first having multiple UHF channels, on a 19" 1400-chassis HMV, is that we all, including my mother who was readily daunted by controls, learned pretty quickly which way to wind the tuning knob to get from whatever channel the set was tuned to, to the one we wanted. Yes, that would take a few seconds, so the simplicity and instant effect of pushbuttons were welcome when they came along, but especially in portable models where costs were at more of a premium rotary UHF tuners must have remained on the market for quite some years. Cheap 5" monochrome portables made when CRT production was winding down of course had rotary tuners to the last.

Incidentally the very small colony of colour sets here includes both a B&O 3200, which if it's fortunate will sooner or later receive the attentions of some brave soul who won't be me, and a KV-1800UB, working when last tried but with a moderately tired tube.

Paul

 
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Re: the most popular 70's colour set

Post by crustytv » Sun Apr 10, 2016 11:52 am

Hi Gary you asked this question back in December

405 fan wrote: just wondered what the best selling colour set was in the 70's .
Regards.
Gary.

I responded with the following
CrustyTV wrote:Its going to be difficult to say without having accurate records, then there's always going to be peoples recalled personal slant/preference. Leaving that aside and going on sheer chassis numbers produced and hence placement in peoples living rooms, I would have to plump for the BRC/Thorn 3000/3500. That chassis was to be found in so many popular models of that period.

Well I found a Trade publication today in my data library, one which I had not read, it was from August 1980. Looks like I was right. In this article they state the 3000/3500 had the greatest number of sales of any CTV with many still in use right into the 80's.

 
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Re: the most popular 70's colour set

Post by slidertogrid » Sun Apr 10, 2016 1:16 pm

CrustyTV wrote:Well I found a Trade publication today in my data library, one which I had not read, it was from August 1980. Looks like I was right. In this article they state the 3000/3500 had the greatest number of sales of any CTV with many still in use right into the 80's.


There certainly was a lot of 3000s and 3500 s in use in this neck of the woods well into the 1980's. The arrival of channel 4 limited the appeal of the earlier 4 button sets as we could get two ITV stations in Peterborough. so you needed 5 buttons!
I can remember selling 3500s and 8500s off as cheapies around 1984 as they were becoming a bit long in the tooth for rental.
It's strange how sets suddenly disappear, I remember thinking that of the Philips G8. It seemed one week we saw the usual few roll in and then the next thing you haven't seen one for a while.... I remember saying to one of my mates sometime in the late 80's or early 90's that we ought to hang on to an example of some of the popular "colour boom" models for future posterity, as the odd one still occasionally turned up as a Part ex or no go repair, but with the exception of a couple of family sets and a Thorn 2000 which we managed to stash it didn't happen.. :ccg

In retrospect the late 70s early 80s were the best years for the independent engineer, customers were pleased to see you, (mostly!) you could fix almost everything in the home, the sun shone and the Escort vans went on forever....
:cca
Rich.
Last edited by Cathovisor on Sun Apr 10, 2016 1:33 pm, edited 1 time in total.
Reason: Fixed quotation.

 
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Re: The most popular 70's colour set

Post by ianj » Mon Apr 11, 2016 11:55 pm

In the early 1970s my Nan and Grandad bought a Philips G8 and used it daily without fault or issue until 1990 when the picture cramped up at the top. It was replaced with a Pye 16" colour portable that was faultless until 2004.

I would say the most popular colour set in the 70s was the rental ones from Thorn, followed by the Philips g8.

 
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Re: The most popular 70's colour set

Post by Wolfie » Tue Apr 12, 2016 12:56 pm

rob t wrote:" B&O 3400 (26" 110 Deg. hybrid) cost just £50 more than a 26" G8; "
That was 2 weeks wages quite a bit more expensive!
Rob T


And you could always cook yer tea on it if the gas ran out...

My money would have to go on the G8 as being the most popular the 3 companies that had the pleasure of my presence in the 70s all had shed loads of them.

 
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Re: the most popular 70's colour set

Post by crustytv » Tue Apr 12, 2016 1:05 pm

Wolfie wrote:My money would have to go on the G8 as being the most popular

As posted above........
CrustyTV wrote:Well I found a Trade publication today in my data library, one which I had not read, it was from August 1980. Looks like I was right. In this article it states the 3000/3500 had the greatest number of sales of any CTV with many still in use right into the 80's.

 
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Re: The most popular 70's colour set

Post by Wolfie » Tue Apr 12, 2016 3:16 pm

Damn, wrong again... no wonder my hoss fell at the second fence on Sat.. :ccb

 
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Re: The most popular 70's colour set

Post by colourmaster » Tue Apr 12, 2016 5:11 pm

Hi everyone
So the BRC 3000/3500 was the most popular set , I bet it wasn't the most reliable.
Regards.
Gary.

 
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Re: The most popular 70's colour set

Post by malcscott » Tue Apr 12, 2016 5:18 pm

Around the Bishop Auckland/Wear valley area there was heavy population of Rediffusion sets due to the factory at St Helens. Staff had the chance to buy sets with a very good discount. The G8 ran rings around the 3000/3500 for reliability, Malc.

 
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Re: The most popular 70's colour set

Post by colourmaster » Tue Apr 12, 2016 6:01 pm

Hi Malc
I would agree with that , did rediffusion have a G8 version ?.
Regards.
Gary.

 
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Re: The most popular 70's colour set

Post by malcscott » Tue Apr 12, 2016 6:12 pm

Hi Gary, they had load of G8 sets out but never badged them as Rediffusion. They also had Decca Bradfords but they were badged as Rediffusion, Malc.

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