Monday 30 July 2012

Pye T25Y 19" Slimline TV

Here is another version of the Pye T25Y. This one has a 19" picture tube and is a later production model made in 1971.
It does have legs but were removed when it was transported as this was part of the haul of old TV's that I got back in early January.
Quite a smart looking set with clean lines, Formica cabinet and I love the "Transistorised" slogan on the front. I guess Pye would have been moving the 'Solid State' slogan back then as it was 1970's and this chassis still uses mostly valves. Mind you valves were coming to end by this time and with colour being around the corner.
According the previous owner, this thing did work but not very well.
So just some pictures for now, will update when I get to working on this.

Friday 27 July 2012

Homebrew 1960's Black & White TV ** This set no longer exists **

I should have really posted this set up on here ages ago, but kind of forgot about it until recently while going through some old photos on my backup hard drive.

Back in October of  2010 I got a phone call from a friend who was contacted by an old lady to say that she had her deceased husbands 'home made' TV set in her garage that she wanted to give away. Naturally I was the first person he called!

So I made the trip to her place and she told me the story about how her husband who was a TV technician and worked for Broadcasting would make a trip every few months or so to the UK for training/courses/seminars to keep things in line with television broadcasting here in NZ at the time.

Not sure how/why or when he decided to make a TV of his own, guess he had the knowledge and the fact that TV sets were rather expensive back in the 1960's so it more than likely prompted him to do it.
Apparently so the story goes that when he went to the UK, he would bring bits of it back in his luggage. He once got interrogated by Customs as to what these parts were and when he told the Customs Officer that it was television parts, the officer laughed and said "Television Parts? We've only just got Television so these cannot be!....Bugger Off!"

So the set was made up of what seems to be very much an English Thorn chassis and from what other information I've gathered the yoke and picture tube are Pye. The cabinet is custom made and the speaker and grille are Philips. Interesting also how the chassis is split rail, one up top and the other down below, makes for easier servicing and the top panel hinges up.

This would definitely be a 'one off' television set and I highly doubt there would be any others, unless he built another for some reason. I have to admit thought it is quite nicely made although some of the wiring and the wires going to the yoke/crt base etc are quite short which does make working on it a bit tedious.

I did fire this up using the variac not long after I got it, confirmed that it had EHT and an image of some sort - frame collapse and looking at all those horrible little hunts caps all over the place I didn't run it for too long and having no vertical drive didn't help either. Started poking around in the vertical section and found the vertical oscillator blocking transformer to be open circuit one side. Discovering that transformer was faulty kind of stopped me for going any further with it and I just put it back together and left it.

Fast forward to one year later when in 2011 another radio friend who knows I collect TV's was offered some old pictures tubes and TV chassis/parts from someones attic which he took and put aside for me. Little did I know that one of these chassis's would end up being almost exactly the same as the one in the home brew TV and even better it came with a service manual and circuit and the best part was is that it had the transformer I needed! I couldn't believe it out of all the odd ball things you come across what are the chances that another complete donor chassis would be in amongst it all!
This is also how I identified the chassis as being  a Thorn variant thanks to the guys on the UK Vintage TV & Radio forum.

But this is as far as I've gotten with this home brew TV...I might make this my next project as I feel it does deserve some attention.

Plenty of photos thats all on this one for now..... Watch this space! :-)

Updates coming very soon...I have doing work to this beast...7/6/2013


Right hand side
Left hand side
Chassis view

Line output section

Control Panel/Tuner
Underneath top chassis

Another view
Underneath bottom chassis

First attempt at powering up..good signs apart from no vertical.

Donor chassis

Wednesday 25 July 2012

Pye T25Y 16" Portable TV - Updated 24/5/2019

Here is a smaller set from my collection, it has a 16 inch CRT and of a hybrid construction so has valves and transistors combined together. Has a total of nine valves.
This one was manufactured around 1969 which was getting towards the end of the monochrome era. I believe that black & whites sets stopped being made here in 1973 with the advent of colour just around the corner.
These were popular sets in their day and were pretty reliable, this one I've owned for many years and recall getting it for free. I did work on it briefly back in 2003 and from memory had some problems with the vertical and didn't go any further with it.
Nice and easy to work and nothing in these are too difficult to get at. The flyback sections uses a compactron valve 38HE7. This valve has the boost diode and line output pentode all in one. A lot of American sets used valves like this in their portables and larger sets as well.
More below...



Chassis hinged down

Close up of line output/EHT section

Valve/Transistor locations.
I decided that for my first project for the resuming hobby and the new workshop being all setup and ready to go was to resume repairing this and to get it working properly this time around.

Upon applying some mains after its long slumber the set came to life displaying a crappy raster crackling audio and some arcing noise accompanied by hissing EHT which turned out to be the lead from the line output transformer to the top cap of the DY87 was about to fall apart. Once that was repaired and sorted I moved on to looking into the vertical to see what was up there.

Discovered pretty quickly with the aid of the circuit that some twat (not me) had attempted to repair it by putting wrong value components in place not to mention a cap tacked across pins on ECL85 on the print side to try and compensate for whacked out frame operation which wasn't even meant to be there! So the putting the correct parts back in place and removing the bodged capacitor, the vertical was starting to look more normal again and height/linearity controls now worked properly!

Now moving onto the horizontal, it worked but the sync was poor and lock was very touchy etc and it didn't take long to discover that the phantom bodger had been there as well changing component values and linking things out again around the ECF802. I wonder what the logic behind doing this and obviously there was some fault that kept this person experimenting around with the circuit and the reasons why - who knows? Putting the right value components back in this area made things a bit happier and more stable and I could now obtain good horizontal sync and lock.

With these two areas sorted I then focused on the resistors that were used in this model and several others. These mustard bodied types are notorious for going high ie 47k reading 70k, 100k reading 180K etc so I make a point of checking all of them and replacing and this was no exception as I ended up changing nearly all of them, I probably didn't have to due to tolerances within the circuit but as I have a 'ton' of NOS resistors and paranoid about old crappy resistors! Its more a piece of mind thing knowing that they've been done. I did leave one or two in there that weren't in any crucial positions and did notice slight improvement as I methodically put new ones in and tested the set in between.

Once I'd done the resistor-rectomy, then removed the leaky/aged old can multi section filter capacitor and fitted replacements using three separate ones. Went through and replaced other old capacitors that looked a bit tired or were not reading right on the cap tester.

Things were now starting to look quite good by this stage so I set about cleaning the case and the front panel/glass etc when the picture vanished...Hmm ok what did I do?? A bit of probing and it returned. Swing the chassis up - no picture, swing it down - picture! Turned out to be a poor solder joint on tag strip in the fly back area probably done by me as I did work on that bit in the past. Then the picture began to fade away at will now - what the heck! Glancing at the filament on the CRT it was dimming up and down. This was an intermittent break in one of the filament wires so fixed that and then the other filament pin terminal decided to break off on tube neck socket!

A few other things went wrong as they do put a wrong value resistor in and was greeted with magic smoke from it the moment I applied power, slipped with the meter probe and blew up the 2nd vision IF Bf137 transistor, burnt the side of my hand a little on the baking 38HE7 during a moment of being careless- man those things get super toasty hot! But not too many hiccups really.

Once I had the set running stable, went to set the picture up using the test pattern and got it reasonably well adjusted there's a slight geometry error horizontally but not going worry about that after all its a 50 year old TV. The yoke correction rings have been adjusted to best as possible.

So after all that and taking 15 years to finally fix this thing,we now have working usable TV! The photos don't do the image justice its bright, sharp with good contrast so the CRT is showing no signs of any issues.

I'll run it over the next weeks to see if any further teething issues crop if but overall am happy with the outcome and feel a sense of achievement on this since it was probably one of the very first valve sets I decided to restore back in the 2000's.

Final Result - The photo doesn't do the picture quality justice.

The pile of worn out/dead parts

Birds Eye view - Most resistors/capacitors replaced.


Monday 9 July 2012

Pye Marketing News August 1974

I was given some very rare New Zealand Pye Factory News Bulletins from the mid 1970's to early 1980's so naturally I thought the best place to scan and post them up was here!

This one is about the release of the Pye Vidmatic CT102 Colour Television.

Many thanks to Graham Street who kindly donated these to me.