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CrustyTV, you want a Thorn 4000? Really?

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irob2345
(@irob2345)
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Are you some kind of masochist?

AWA's introduction to colour in Australia was with the Thorn 4000, known here as the 4KA.

I used to do warranty service at the time and about 50% of the time it was on 4KAs.

The version we saw had a VHF rotary tuner and a mains isolation transformer.

There were so many service bulletins on this chassis it got well out of hand.

AWA eventually made little PCBs to replace all the thick film circuits in production, these were available as spare parts. That, and the replacement of all UK sourced parts with local equivalents, eventually established some semblance of reliability. The Mazda CRTs were replaced with RCAs (brighter, but with terrible colourimetry).

But it was all too late, the damage had been done to AWA's reputation for making a reliable product. A Mitsubishi G chassis (locally produced) was grafted in. Performance not great but at least it was reliable.

If you want one (I suspect they all went to landfill a long time ago) it might be worth posting something on the Australian Vintage Radio and TV forum.

 
Posted : 24/07/2020 11:26 am
Nuvistor
(@nuvistor)
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@irob2345

That was a post with feeling, appears you had a few fun and games with this chassis. I never saw many Thorn sets and definitely not a 4000.

Chris can answer for himself but I know he would like to complete the range of Thorn sets he has.

 

Frank

 
Posted : 24/07/2020 1:00 pm
crustytv
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Nothing I didn't already know and was pretty much covered back in March here. Still want one though.

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Posted : 24/07/2020 5:03 pm
jcdaze
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@irob2345 I also worked on a lot of 4000's both in the UK and in Germany(Essen and Dortmund) and I want to stand up for that chassis. Thorn had a rental set up in Germany at the time and during the build up for the world cup in 1974 they were flying out of the door. I thought they were very well engineered, granted maybe over engineered, and they were let down by two main things; A, the thick films circuits and B, customers expectations were rising and they started expecting the set to work straight out of the box and that was just a crazy idea. That is my case for the defence. 

 
Posted : 24/07/2020 9:05 pm
Nuvistor
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@jcdaze

One problem was that Hitachi and Toshiba sets did work out of the box and carried on working, they had been shipped all the way from Japan. Pye/Ekco sets from that time the 697 chassis very often required repair and setting up before sales. They were fitted in my opinion with some poor quality components, can’t understand how they got through QA.
The middle 70’s were not a good time for some UK TV set makers.
I have no experience of the Thorn 4000

 

Frank

 
Posted : 24/07/2020 9:52 pm
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irob2345
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Well when you compared it to contemporary local designs (well maybe with the exception of HMV) it didn't stack up well.

People DID expect them to work straight out of the box! But in the early days it was the practice for the retailer to deliver the TV and we'd be sent to set it up.

Colour took off in Oz big time when it was introduced and we were very busy fixing mainly dead or sick AWA 4KAs.

The Krieslers (a local design loosely based on the Philips K9) we also handled DID work straight out of the box and they were a joy to work on, with consistently beautiful pictures and pretty good reliability.

I hate to say it, but much of it came down to the reliability (or lack thereof) of UK sourced components. Our local components industry was still largely intact in those early days of colour and there is no doubt that the reliability of local parts was much better. Japanese parts were better still!

 
Posted : 25/07/2020 12:34 am
irob2345
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Come to think of it, other designs that used the thin neck delta CRTs weren't much better. The Blaupunkt KC chassis comes to mind.

AWA seemed to have imported the 3504s in two waves. The later ones were better, with some more reliable components. There were no spares imported for these, a large number of TVs were scavenged for parts.

Some years later I fitted a much newer CRT (self converging inline gun) complete with glued-on yoke to a 53cm 3504. It worked surprisingly well. The entire convergence "flap" was discarded. I needed to turn the HT down to about 48 volts to get manageable EHT. Set ran cool in this mode and lasted for many years at my sister-in-law's place, probably still working when it was discarded.

 
Posted : 25/07/2020 3:18 am
crustytv
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The 4000 circuit description - including student course notation, has been kindly donated by Jim (jcdaze) and placed in the sites Technical data library.

CrustyTV Television Shop: Take a virtual tour
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Posted : 25/07/2020 9:39 am
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Red_to_Black
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Thanks to both yourself and Jim for this, I will have a read, time permitting,

We never had access to this stuff back in the day.

 
Posted : 26/07/2020 5:57 pm
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irob2345
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Well I must say AWA were very good with training materials and we had vinyl folders for both the 4KA and the 3504. They were very well thumbed!

Actually all the manufacturers were good with training and service documentation. Based on overseas experience everyone in the industry pitched in and did their best to make it work. And it did, with factories running 3 shifts trying to keep up with the demand.

A new startup, Rank Arena, built NEC TVs here under their badge. They became the top selling brand. The manuals were compiled in Japan and had the occasional comical Jinglish phrasing. Their slogan on the front of the manual read:

Better Service

Better Reputation

Better Profit

Rank would import some TVs of the same model as those built here to keep up with demand. Interestingly, the Japanese built sets were not as well put together as the local ones. You always had to do a full purity and convergence job on the Japanese sets, not so for the locals.

 

 
Posted : 27/07/2020 1:47 am
Nuvistor
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@irob2345

Was the convergence/ purity problem possibly anything to do with the change in Hemisphere?

 

Frank

 
Posted : 27/07/2020 3:48 am
irob2345
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No doubt, but other Japanese makers used calibrated magnetic fields to compensate for this.

Also the way the statics and convergence yokes were set up caused keystoning, it was just sloppy, surprisingly.

CRT was 1st gen Toshiba RIS. There was an art in getting them to work up to their capabilities but they did work well when you did.

 
Posted : 27/07/2020 4:17 am
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