Pye T26 (monochrome) TV schematic wanted.
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Location: Melbourne, VIC
Member since 26 February 2014
Member #: 1517
Postcount: 29
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Hi All,
Just wondering if anyone might have a nice copy or scan of a Pye T26 TV ???
This particular b+w TV was used at Box Hill Tafe to train upcoming techs in the TV/Radio services course, which is what I did.
The instructors would create different faults in each TV, and we'd have to locate the problem and fill in fault-sheets indicating what we found and how to fix, then move onto the next set...
Simply for nostalgia's sake, i'd like a copy to print/frame and hang in my workshop.
Thanx in advance,
Marty.
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Location: Wauchope, NSW
Member since 1 January 2013
Member #: 1269
Postcount: 576
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My local TAFE campus used small 12" B&Ws and 14" colour sets for that! They used awesome little 12" Tempest portables from the 1980s (I'm a proud owner of one now) and NEC N-3410s and 3480s from the 1990s/2000s.
Chris
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Location: Melbourne, VIC
Member since 26 February 2014
Member #: 1517
Postcount: 29
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Haha you're lucky, our colour sets were all Phillips K9, K11, K12's etc....
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Location: Ballarat, VIC
Member since 4 January 2011
Member #: 803
Postcount: 456
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The Pye T26 was a proud moment for the Pye chassis designers. I've sent a copy of the circuit to be attached to this post.
The Philips Australian colour TV chassis series (K9 - KL9) are amongst my favourite designs. They were all locally adapted versions of an European design but were well built and fairly reliable.
The only exception was the K12A chassis. A bit too well designed (i.e. too complicated) and had some teething troubles! The K12A chassis are rare series of models to find these days compared to the others.
Click image to see higher resolution.
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Location: Melbourne, VIC
Member since 26 February 2014
Member #: 1517
Postcount: 29
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Thanx TV Collector for my Nostagia fix...
The T26 was a great little set to work on....probably why we had them at tafe
Yep, I preferred working on K9's instead of K11/K12's and variants.
Thanx again, so much
Marty.
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Location: Silver City WI, US
Member since 10 May 2013
Member #: 1340
Postcount: 977
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There was a young bright Pye engineer giving a presentation on this design c.1970 and I caught his visit to Brisbane at the Institute of Engineers, Upper Edward St, Spring Hill.
This indicated that it was a ground-up Australian design.
TV Techs were invited as the theme of his presentation was, you could say:
"Transistors are Easy to Understand, Diagnose, Fix"
He then went through a full circuit description/explanation.
Here's some points I remember him making:
* "We have a jumpable resistor in primary as voltage in W.A. can be 260v"
* "We now seek to eliminate pots (such as Vert Lin) as transistors can be cheaper than pots"
* He called voltage sources "Rails"
* In his didactic style, he introduced the 'bootstrap' circuit explaining the term was an (archaic) "Americanism" meaning magically elevating oneself by pulling up on boots, thus circuit would "lift" input impedance.
Can anyone see the bootstrap circuit to which he referred? I think I remember where it is!
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Location: Silver City WI, US
Member since 10 May 2013
Member #: 1340
Postcount: 977
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At the lecture, the TV on display was a 12" portable but I'm sure it was the same design as the 17/25" posted schematic?
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Location: Ballarat, VIC
Member since 4 January 2011
Member #: 803
Postcount: 456
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The 12" portables used a different chassis to the large screen sets. The T26 chassis was physically to big!
The early portables used the T25 chassis. I believe the bootstrapped circuit you're referring to was in the vertical deflection amplifier.
It seems to be an increasingly overlooked fact that Australians had the ability to design as well as build our own electronics! While many companies did "borrow" designs from overseas affiliates, many companies also did completely in house work. In the case of Pye, all TV chassis designs from the T18 to the T34 are local. This includes the colour TV's as well, quite an achievement for a relatively small company.
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Location: Silver City WI, US
Member since 10 May 2013
Member #: 1340
Postcount: 977
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T-25, that would make sense.
It was a smart looking little set they had on display and they were justly proud of it. Would be good to find one, a real classic!
Anyone got a picture of this portable or schematic?
I too was thinking it must have been the Vertical where he described the bootstrap as it has normal DC feedback and heavy AC feedback (C512) the bootstrap cap? "lifting" the emitter resistance? helping the hi-Z sawtooth generator on the base? The engineer explained that night " wherever you see a sawtooth generated, look for a charge and a discharge circuit path"
I see it used Aussie "AX"Fairchild transistors showing the level of local design/manufacture that wasn't to last unfortunately
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Location: Ballarat, VIC
Member since 4 January 2011
Member #: 803
Postcount: 456
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The portable your thinking of might have been the model 12F-1 which uses the T25 chassis.
Your memory is excellent! I was reading the circuit description for the T25 and your memory of it matches the manual quite well. C81 is the bootstrap capacitor on the circuit diagram.
Click on circuit diagram for larger resolution
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Location: Wauchope, NSW
Member since 1 January 2013
Member #: 1269
Postcount: 576
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Administrator
Location: Naremburn, NSW
Member since 15 November 2005
Member #: 1
Postcount: 7290
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That telly would have gone well in a loungeroom full of Parker or Chiswell furniture.
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A valve a day keeps the transistor away...
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Location: Daylesford, VIC
Member since 13 January 2011
Member #: 809
Postcount: 326
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But where's the loudspeaker?!
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Location: Wauchope, NSW
Member since 1 January 2013
Member #: 1269
Postcount: 576
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The speaker is behind the perforated metal grille below the tuner I believe, similar to Astor R11P-7 portables.
Chris
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Location: Silver City WI, US
Member since 10 May 2013
Member #: 1340
Postcount: 977
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I hadn't checked back to this thread for a while, wow what a surprise seeing the stylish little Pye again! What a gem - and more a gem for its no-compromise engineering!
And thanks for posting T25 schematic as well - I'm enjoying analysing its elegant innovations, ahead of its time!
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