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CTV Spanish Thorn 3500 : Inter TVC366

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Had a very interesting contact on YouTube to my Thorn 3000 PSU video. Apparently 10,000 3.5K's were manufactured in 1974 for the Spanish market by Inter, later Inter Grundig. I had no idea about this and was very curious to see what it looked like. Internally not a lot of difference, Jose details what these changes were. Outside it looked like nothing I've seen from the Thorn stable.

I thought some ex Thorn engineers, like John and Jim, might find this fascinating, but unlike me, you might have already been aware of all this.

Posted on Radios-TV Vrat YouTube Channel
Jose Ramon Ramos Reina
Good afternoon, at home I have two "Inter TVC-366" (Spanish version of the BRC 3500 from 1974) working perfectly, one of them for daily use with a DVB HD tuner coupled through a VCR, I learned the trade with them, I rebuilt them in 1985 in my father's workshop when I was 15 years old, my father had already scrapped them, great headaches to make the damn power supply work, when I took the air they were already repaired in 10 minutes because they were still working in my area and we were the technical service of the brand, my father hated them ha ha, in 2008 the power supply that is used daily died, it broke every 10 - 15 days, I decided to put all the Possible new components and since then it has not had any failure, if it broke tomorrow surely you will not remember how it was fixed hehe.
Apart from the power supply, only one video output transistor has failed, the vertical circuit capacitors, the EHT tripler, and when it was restored I made the reform to eliminate the lines that came out above the teletext.
In 2005 I got a new CRT.
I responded saying, "can you provide some internal photos as I'm curious to see inside, I had no idea 3500 sets were used in Spain".
Posted On Radios-TV Vrat YouTube Channel
Jose Ramon Ramos Reina

@Radios-TV  Good afternoon, Few were manufactured (around 10,000 units), in my area there were 13 units, they were assembled by the INTER brand (later INTER GRUNDIG Spain) in 1974, from 1975 to 1978 they assembled Blaupunkt chassis, in 1978 it was absorbed by GRUNDIG taking advantage of the large infrastructure and existing technical services (one of ours) There I give you a flickr link of three photographs, the power supply and the chassis. The Spanish power supply has one less transformer because it is installed separately for 125/220 V operation (Very large), the upper plate of the rectifiers is Spanish, the lower chopper plate is exactly the same as yours. The video, convergence, beam limiter and line output cards are exactly the same as yours. The vertical output plate and the sound amplifier is different, Spanish too (the sound is very very good, a woffer for bass of 8 "and a twetter for treble of 3") The intermediate frequency plate is similar adapted to the Spanish broadcasting system with some modules welded on it. The chroma plate is also the same as yours, it only has the bridges activated for 625 lines.

TVC366 1
TVC366 2
TVC366 3
TVC366 4
TVC366 5

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Topic starter Posted : 11/06/2021 10:58 am
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@crustytv I don’t know Interbrand but I did see the export versions of the 3000 chassis which was known as the TX 500. Main difference was that the sets had vhf/uhf tuners and the I.F. board incorporated a couple of chips. I know a number of them were exported and maybe they were re-badged as well.

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Posted : 11/06/2021 11:52 am
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Another picture of the export version of the Thorn 3000 chassis.

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Posted : 11/06/2021 3:04 pm
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I’d heard of TX577 which I think may have been the Antipodean version of the 3500 but totally unaware of the Spanish version. The look of the Inter set has no Thorn styling cues at all to me and I would never have guessed from the front.

Jose mentions the use of a different frame and sound module, wonder if this was just a bit more attention to audio as I see the set has in/out audio facilities. Shame they didn’t improve the annoying Teletext lines problem. When twelve lines fir data was eventually used these could no longer be removed by careful set up and we’re very obtrusive.

Thanks for the additional circuit details JC.


Posted : 11/06/2021 6:20 pm
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A fascinating post. I wonder how many other export versions of the 3000/3500 chassis there were?

Posted : 14/06/2021 10:19 am
Till Eulenspiegel
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Some or all export 3000 series receivers were fitted valve rotary VHF tuners for system BG countries.  The mains transformer has a winding to supply the valve heaters.

Till Eulenspiegel.

Posted : 14/06/2021 11:45 am
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The 3504s that came to Australia in 1974 (in the mad scramble to source enough CTVs to meet the demand) had full mains transformers (live chassis is a sales killer in Oz) and a Matsushita VHF only turret tuner. Not a valve one.That was prior to Band 2 clearance - yes, we used to have TV channels in Band 2 - and before the introduction of UHF.

They were branded AWA and Thorn and there were 53cm and 63cm examples in basic cabinet styles. The company I worked for at the time had some in their rental fleet - not the most reliable TV on the market by a long shot and the Mazda CRTs fitted to the early examples were a long way from competing with what else was around at the time. I grew to like them, I was the only tech where I worked who did. Well set up and when fitted with the later Sylvania CRTs, they were nearly as good as the NECs and Pyes they tried to compete with.

The reason AWA-Thorn imported these sets was because they were having so much trouble making the Thorn 4000 series chassis (called the 4KA here) run for 3 months without breaking down. Eventually all the thick film modules were replaced by little PCBs. Then they changed over to Mitsubishi designs, stuffing boards and assembling from kits.

Oh, 1974 Aussie Pyes were a totally different animal to UK Pyes. They had the then very new Toshiba RIS CRTs and a simple, no-nonsense design. Very little Philips influence save for the two swing-out PCBs in the style of the K9, the E-W modulator and a couple of 1st-gen. Philips ICs (TBA510, TAA630) in the chroma.

Posted : 14/06/2021 12:25 pm
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That reminds me that Thorn also sold a colour TV receiver in New Zealand in the early days of colour – I am not sure what model. It was not highly regarded. Anyway, at the Auckland Easter Show of 1973, ahead of the colour TV start in October that year, there were quite a few colour receivers on display. One of them was the Thorn model. As I recall, as compared with the others, it looked somewhat “agricultural”, both inside and out, as did the displayed picture. During a conversation with the chap on the Thorn stand, I asked the question as to why the receiver was not fitted, at least optionally, with an audio output suitable for feeding the sound to a hi-fi system. I didn’t get a satisfactory answer, some mutterings about difficulties and the cost increment. So it was interesting to see that the Spanish Thorn from the same era did have exactly that facility; the Thorn NZ guy was evidently unaware of that and how easily it was done. To be fair, none of the early NZ colour TV receivers had that facility. Philips NZ at least were able to offer advice as to the best way to install an audio out facility. It also noted that in Europe, an audio transformer was available for that purpose – I gather that the European K9 had a cheapskate non-isolated power supply, whereas the NZ version was fully isolated. That was anyway long-established normal and modal practice for radio and TV receivers in NZ, and I have a recollection that it was by then mandatory, covered by a then-recently revised NZ standard. (As well as safety, potentially corrosive DC earth currents were a concern. Going back to about 1920 (we not only electrified early, but also standardized early), NZ had a MEN (multiple earthed neutral) supply system, with neutral solidly bonded to a local earth at each consumer switchbox, so the earth path was readily available, not a problem with AC, but corrosive to water pipes with the DC element from non-isolated receiver power supplies.)

Re Pye in NZ, its initial colour receiver range was basically rebadged Philips, but in 1974 (or maybe it was 1975) it introduced its Vidmatic model with an in-line gun tube. It also had a fet-based rotary VHF tuner, which made a big difference. I am not sure wherefrom the tuner came, as the European makers were very slow to adopt fets. The bipolar VHF tuner used in the Philips K9 was awful in respect of cross-modulation, even with just one Band I and one Band III channel. It required 18 dB of aerial input attenuation to handle without cross-modulation a signal that a bog-standard monochrome receiver handled with no problems at all.



Posted : 16/06/2021 12:30 am