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Old 3rd Dec 2023, 12:52 am   #21
Maarten
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Default Re: Large screen solid state monochrome sets.

In 1970, continental Philips wasn't even producing their last generation hybrid colour chassis K8 yet, or maybe just barely by the end of 1970. The demand for 110 degrees sets must have been high while the transistor design wasn't ready yet. So high that The Netherlands, Germany and Austria/Sweden each produced their own quite different versions of this hybrid chassis. The swedish version K80 was even produced well into 1973. The earliest fully transistorised K9 colour sets were introduced around the spring/summer of 1972 in 22" version. The 26" version probably came a few months later and later 22" sets were fitted with the 26" version of the chassis. The 22" version had been kind of a prototype so it can be argued that real mass production only started in late 1972/early 1973.

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Old 4th Dec 2023, 11:01 am   #22
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Default Re: Large screen solid state monochrome sets.

Tim - about the Philips 320 being like a G8 without the colour bits. I always thought it had more in common (glow switch, single transistor output stage) with the infamous Pye CT200.

I think you might have hit the nail on the head by saying you couldn't fix a 320 with a neon and polo mints. Many time served repairers of the time were understandably daunted by colour but found hybrid mono sets easy to repair. Given that most of their customers were loyal elderly people who preferred mono, it enabled them to carry on for more years, and these small shops were the main dealers for Decca, Bush and so on, leaving Thorn to the big boys.

Regarding the large screen Philips being badged Pye, independent dealers in the Eighties were sold Pyes to compete with the big sheds and ther Philips TVs. I bought CP90/110s and so on badged Pye as well as the large screen monos which the big retailers had no interest in.
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Old 7th Dec 2023, 11:02 pm   #23
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Default Re: Large screen solid state monochrome sets.

From a 1971/72 HMV sales catalogue. Three 24" models, the 2815 de luxe model with vari-cap tuning. Another teak cabinet model, the 2804.
The budget model 2808 is apart from the badge identical to the Marconi 4808. Also available in is the dual standard version, model 2668.

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Old 8th Dec 2023, 10:08 am   #24
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Default Re: Large screen solid state monochrome sets.

Correct me if I'm wrong, but I don't think the Thorn 1615 series was sold in a guise other than Ferguson for retail sales. Also was there ever a 24" version?

These were clearly budget models with their flimsy cabinets and controls - sliders that broke off and became noisy and poor quality channel selectors, together with the poor quality CRT. A miilon miles from the 'hewn from a tree' look of the HMVs above!
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Old 8th Dec 2023, 10:46 am   #25
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Default Re: Large screen solid state monochrome sets.

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Correct me if I'm wrong, but I don't think the Thorn 1615 series was sold in a guise other than Ferguson for retail sales. Also was there a 24” model?
Yes, model 3852.
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Old 8th Dec 2023, 11:11 am   #26
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Default Re: Large screen solid state monochrome sets.

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From a 1971/72 HMV sales catalogue. Three 24" models, the 2815 de luxe model with vari-cap tuning. Another teak cabinet model, the 2804.
They are all still (hybrid) 1500s aren't they? I've not heard of the 1525 chassis, presumably the difference is the varicap tuner. A big resistor and a TAA550 tacked on somewhere then?
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Old 8th Dec 2023, 11:17 am   #27
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Default Re: Large screen solid state monochrome sets.

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About the Philips 320 being like a G8 without the colour bits. I always thought it had more in common (glow switch, single transistor output stage) with the infamous Pye CT200
Well, sort of, except that the 320 had the same tuner and the nice IF gain and selectivity modules from the G8. The Pye CT200 had that dreadful IF PCB where the coils were never quite soldered in properly and caused endless problems - didn't LedCo make a SWAF version to get around this?
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Old 8th Dec 2023, 11:25 am   #28
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Default Re: Large screen solid state monochrome sets.

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The Pye CT200 had that dreadful IF PCB where the coils were never quite soldered in properly and caused endless problems - didn't LedCo make a SWAF version to get around this?
Yes, they did. I have one somewhere.
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Old 8th Dec 2023, 11:29 am   #29
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Default Re: Large screen solid state monochrome sets.

Yes, we fitted quite a few LEDCo boards but to be honest the results were disappointing, probably showing up the set's other shortcomings!

I quite liked the 320, especially the 17" version. The rotary channel selector did need cleaning but was a vast improvement on the G8's tip switches, though I was particularly adept at replacing the channel knob upside down...

The large screen versions gave the impression of being a real slimline TV and, as you pointed out, thanks to the G8's vision/selectivity modules, gave a good crisp picture.
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Old 8th Dec 2023, 12:20 pm   #30
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Default Re: Large screen solid state monochrome sets.

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Correct me if I'm wrong, but I don't think the Thorn 1615 series was sold in a guise other than Ferguson for retail sales. Also was there ever a 24" version?
I believe there was an Ultra branded version made for sale from wholesalers.
Model type 6852?

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Old 8th Dec 2023, 3:11 pm   #31
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Default Re: Large screen solid state monochrome sets.

The Pye CT200 had a low voltage focus, the pictures were always soft. the CT218 had a high voltage focus tube, the pictures were much better. The I.F can was always full of dry joints. Like Glyn we updated them to the SWAF type. Bob
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Old 8th Dec 2023, 7:27 pm   #32
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Default Re: Large screen solid state monochrome sets.

Another important piece of G8 technology in the Philips 320 was the TBA550 'jungle' IC that looked after video processing, AGC, black level control, frame sync and part of the line sync circuit. This gave immaculate black level stability (along with the carefully designed high level contrast control) and rock solid line and frame lock, even under poor signal conditions. This was one of four ICs in the set, the others being TBA720 (line timebase), TBA750 (intercarrier sound) and TAA550 (tuning voltage stabilisation).

Its odd that apart from RBM no-one else responded to this statement of technical leadership. BRC were still turning out 1500s, which gives very basic performance indeed by comparison. They may have been easy to fix, but that was about it.

On the subject of other big solid state mono sets, has anyone seen the 'Chassis C' version of the Indesit T24? The 'Chassis B' was the common one, it was a hybrid and looked a lot like an ITT VC200 inside. The 'C' had a similar layout but was all-transistor, it had a simple power supply with all the stabilisation done in the line output stage.
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Old 8th Dec 2023, 9:25 pm   #33
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Default Re: Large screen solid state monochrome sets.

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and TAA550 (tuning voltage stabilisation).
This one had a poor temperature performance which resulted in frequency drifts problematic witout an AFC.
It was later on replaced by the ZTK33 from ITT Intermetall which was much more stable.
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Old 8th Dec 2023, 10:56 pm   #34
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Default Re: Large screen solid state monochrome sets.

The BRC 1500 became a little more solid state when an all-transistor frame output stage was introduced into certain late production sets. Why the circuit designers did this is unclear. The original frame timebase using a PCL85 was reasonably trouble free.
The transistor frame time base was a complex circuit and it's doubtful if there was any production cost benefits.

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Old 8th Dec 2023, 11:16 pm   #35
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Default Re: Large screen solid state monochrome sets.

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Quote:
Originally Posted by Welsh Anorak View Post
About the Philips 320 being like a G8 without the colour bits. I always thought it had more in common (glow switch, single transistor output stage) with the infamous Pye CT200
Well, sort of, except that the 320 had the same tuner and the nice IF gain and selectivity modules from the G8. The Pye CT200 had that dreadful IF PCB where the coils were never quite soldered in properly and caused endless problems - didn't LedCo make a SWAF version to get around this?
The main problem with the original IF module was that the ceramic type capacitors. The ceramic (?) dip extended down the legs so it caused a bad connection on the lead through. If you heated the joint and eased the capacitor back a bit you could then get a good sound joint. This cured the problem every time. The only time I couldn't cure the problem was when the module had been got at by someone with a Weller soldering gun!
We did have the LEDCO panel but found it caused poor definition and AGC problems. True to say though that the sets were past their best by then especially the first gen 110 degree 731 series.
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Old 8th Dec 2023, 11:21 pm   #36
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Default Re: Large screen solid state monochrome sets.

As I mentioned in a previous thread I can remember seeing a large screen B&W TV in the Cash Converters in Stockport in the late 1990s, only realising it wasn't a colour after noticing the low price & details on the label. I think it was a later Pye, as I remember it had a woodgrain case & rounded corners like many early 1980s colour sets.

From what I remember Grundig were making monochrome sets well into the 1980s, I presume solid state.

The Far Eastern sets like the Cap-10 & Plustron were made even later, & some Eastern European ones even later, but rarely imported.
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Old 9th Dec 2023, 10:43 am   #37
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Default Re: Large screen solid state monochrome sets.

I did mention the Indesit T24 C version earlier on, though I only saw a couple. ISTR an array of dropper resitors that ran very hot.

Like many others on here I never saw a 1500 with a solid state frame stage - was it solely for rental? You did post the circuit diagram that seemed quite complex compared with the good old PCL805 - I don't see it being more reliable, but who knows?

Obviously Philips (320) and RBM (A816) decided they could make a first-class solid state large-screen mono TV. Thorn didn't see the point, it seems.

Never saw a Grundig solid sate mono - was there one? The odd Eatern Europe (Unitra) sets were hybrid which came as a bit of a surprise in the Eighties! Picture was dire thanks to the blotting-paper tube.
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Old 10th Dec 2023, 1:40 am   #38
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Default Re: Large screen solid state monochrome sets.

Grundig certainly made 24" solid state mono sets, though maybe only for the continental market? Later sets used Tesla tubes, I think.
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Old 10th Dec 2023, 6:44 pm   #39
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Default Re: Large screen solid state monochrome sets.

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Grundig certainly made 24" solid state mono sets, though maybe only for the continental market? Later sets used Tesla tubes, I think.
https://www.radiomuseum.org/ lists some when I had a look a while back.

From what I remember from another thread they sold some under the Minerva brand.
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Old 11th Dec 2023, 9:56 pm   #40
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Default Re: Large screen solid state monochrome sets.

Going back to the Bang & Olufsen monochrome TV that Tim mentioned, was it designed and made in the UK or was it from Denmark, where B&O originates from? Some countries started colour TV broadcasts later than the UK. Not sure when Denmark started but perhaps they had a few years longer to wait, during which time black and white TV designs were worked on and improved.

I imagine the B&O was quite an expensive luxury set. Probably black and white TV buyers cared more about price than quality, and that explains why there were many more Thorn 1500s sold than B&O sets (in the UK, at least.) Thorn seemed to pursue the lowest cost. They didn't include a black-level clamp circuit, even though the extra components would have only cost pennies.

Philips was certainly committed to large-screen monochrome TV, though the later ones (E2, L7) that I've come across seem to have been made in other European countries, presumably wherever Philips had some spare manufacturing capacity. Designing a set that could be sold in a number of different countries with minor modifications, even using a cabinet design similar to their contemporary colour sets, must have helped Philips get maximum return on their R&D investment. One feature of the L7 monochrome TV is an on-screen tuning indicator, also included in some of their colour TVs. Possibly using the same integrated circuit?

There were some cheap large(ish)-screen solid-state monochrome TVs, typically 17" size, produced in eastern Europe and some Asian countries, sold in the UK. But I never saw any such sets from Japan. Did the Japanese, rather like the British, think it wasn't worthwhile developing them?
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