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B&W TV I found the same model TV I grew up with!

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irob2345
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A fellow collector found this in Albury NSW. in amazing condition:

Hjmn0755

Despite working for over 10 years as a TV service tech I have never seen another example of the TV we had when I was a kid in the 60s. My sister and I watched the Beatles get off the plane in Sydney in 1964 on this TV.

Only ours was walnut, this one is Qld. Maple. Another difference is this one has the earlier T18 chassis, ours had the somewhat rare first flip-down chassis, the T20 that preceded the very long running T21 that was used in the Pye Pedigree. Apart from the timber colour then, it looks identical.

Got it home, pulled the back off (it was nailed on!!) and found it had a newish CRT (that tested 75%)

Img 0426
CRT Label

and it had been partially re-capped. Just as well, T18s were full of wax paper caps. The (absolutely necessary) vertical mod looked like it had been done at the factory.

Still had a couple of papers around the line transformer so I replaced them to give the tranny a better chance of working. This is it with the covers removed to get at the caps which are behind the transformer.

Img 0431

This Line transformer was the early type. I have never seen one of these actually working! The same transformer in our T20 failed inside the 3 months warranty period.

Back in the day they were one of the few line transformers we'd carry as van stock and it wasn't unusual to replace a couple a week. The new ones were much better, they simply did not fail.

So, after replacing a couple of high resistors in the G2, vertical and beam limiter circuits, we have a raster!

Img 0424

So I measured the line transformer winding temperature and let it run for a while.

Temp 19

After 15 minutes, uh-oh:

Img 0434
temp 40

 So where to from here?

Some preliminary checks indicate that a Philips NT3101A (from an HMV PM series chassis) can be adapted.

I worked out a neat way of measuring tap ratios (and hence compatibility) on line transformers using a function generator and a scope. If anyone's interested I'll describe it.

 
Posted : 16/07/2023 12:01 pm
WayneD, ntscuser, Lloyd and 2 people reacted
crustytv
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Nice and interesting to see a TV from Australia, a rare treat for us in the UK.

However, there's no mention in the title or the post content who actually made this TV, other than your reference to a T18 & T20 chassis which means absolutely nothing, well to me, I don't know about others. I take it from the CRT code it's 23" is that correct or not? Again not come across Thomas brand were they your countries CRT manufacturer, a re-gunner or just a rebadge of a UK or USA tube?

Nice looking TV, reminds me of our 600 series Baird console sets, though the side controls make it more like a KB.

Look forward to following your progress, and thanks for posting.

p.s

might be nice to post some circuit snippets as you go, so we can see how it was designed.

p.p.s

Posted by: @irob2345

I worked out a neat way of measuring tap ratios (and hence compatibility) on line transformers using a function generator and a scope. If anyone's interested I'll describe it.

That does sound interesting, feel free to enlighten us. 👍 

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Posted : 16/07/2023 12:15 pm
Cathovisor
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Posted by: @crustytv

However, there's no mention in the title or the post content who actually made this TV, other than your reference to a T18 & T20 chassis which means absolutely nothing, well to me, I don't know about others.

If you look closely at one of the pictures you can see a Pye badge, but it would be nice not to have to play detective.

 
Posted : 16/07/2023 12:25 pm
crustytv
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Hi Mike, I wasn't sure when looking at the badge, now you point it out I see it. That also ties in with Ian stating T18 T20 T21 were PYE chassis'. I should have put all the pieces together and realised it was a PYE TV.

Guess that's why I have this FAQ advice, makes life easier for old duffers like me 😉 but equally helps search engines find TV's. Evidenced by doing a Google search for any popular CTV from the 70s 80s brings up a VRAT thread every time.

CrustyTV Television Shop: Take a virtual tour
Crusty's TV/VCR Collection: View my collection
Crustys Youtube Channel: My stuff
Crusty's 70s Lounge: Take a peek

 
Posted : 16/07/2023 12:35 pm
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Cathovisor
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Posted by: @crustytv

I wasn't sure when looking at the badge, now you point it out I see it.

I remember that style of Pye badge from similar-vintage Pye TVs here in the UK; from memory, the Pye V530 TV with FM radio that we were given by our neighbours, which I think was described as a "consolette" by Pye, had that badge.

 
Posted : 16/07/2023 12:50 pm
irob2345
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S'pose I thought you might recognise it as a Pye!

Yeah I was a little disappointed that it wasn't a T20. Still....

Thomas were one of 5 or 6 CRT manufacturers in Oz in the 50s and 60s.

AWV

Anodeon

Philips

Mullard

Thomas

Mazda (short lived)

Plus about half a dozen tube re-gunners.

AWV, Philips and Mullard also made valves.

Pye barely survived the credit squeeze of 1960 and the T18 and T19 were both low tooling cost "poverty" chassis - you can see the same chassis metalwork in the W101 and W201 from 1956/7. But then in 1965 they released a very brave new design (the Pedigree) that became the number one TV seller in Australia for many years and saved the company.

The other thing that helped was "4 years free service" - in the days when you only got a 3 month warranty from any other set maker. It did force them to make reliable TVs!

A few years back I came across a 24" Pye T26 B&W from 1971 (all solid state) that had never had the back off. An 820k resistor in the CRT G2 circuit was the only fault.

 
Posted : 17/07/2023 8:08 am
irob2345
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Here's the circuit!

Img 0440

Phone camera followed by cleanup

 
Posted : 17/07/2023 9:17 am
crustytv reacted
crustytv
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Posted by: @irob2345

S'pose I thought you might recognise it as a Pye!

Not at all, it's not like any B&W PYE I've ever seen, as evidenced here PYE from 1936 - 1960 which why I asked. As I mentioned above, except for the controls, it looks more like our 600 series Baird.

CrustyTV Television Shop: Take a virtual tour
Crusty's TV/VCR Collection: View my collection
Crustys Youtube Channel: My stuff
Crusty's 70s Lounge: Take a peek

 
Posted : 17/07/2023 9:28 am
Nuvistor
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@irob2345 
The circuit is drawn very similar to the ones produced by the UK.

Frank

 
Posted : 17/07/2023 10:34 am
irob2345
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The drafting style changed suddenly from the T20 to the T21. I believe it corresponded with a change in chief engineers.

T21 was the first chassis to use a PCB. It was reliable and remained in production for many years. to be replaced by the (even more reliable) T23 hybrid. Pye Oz managed to avoid using the Philips Decal valves entirely.

 
Posted : 18/07/2023 9:25 am
irob2345
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That circuit has a bad "feature" that I've seen in other TVs.

Have a look at the heater circuit.

What would happen if one heater was shorted (accidentally, say.)

Answer - the heater fuse would blow and 12.6 volts would be applied to the heaters on the other half of the circuit!

Stupid, eh? But very common.

I encountered a similar situation in a '58 vintage HMV F series chassis.

The heater 12.6 volt centre tap was dry jointed to a chassis lug. It had always been that way.

That was one hell of a long term intermittent fault! It took 60 years to be discovered!

 
Posted : 18/07/2023 9:52 am
Nuvistor
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@irob2345 

Not a problem the UK sets had with the live chassis series heater chains, but we had other problems. A decoupling capacitor in the heater chain going S/C could light up the upper part of the chain among others faults.

 

Frank

 
Posted : 20/07/2023 11:00 am
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