LABGEAR ColourText Model 7026

I broke one of those up in late 1999.The only good thing about doing that was i used nearly all the parts for other things.
It would not receive transmissions and i was told by a tv engineer it was no longer compatible.

Stephen

Hi Chris, So it was you who bid on this then, actually it's a good job you did buy it, because if i had the money and it had no bids towards the end then i probably would have put a pity bid on it. trust me it's not the first time I've felt sorry for stuff as a look in my sheds will confirm

 cheers,Neil.

I found a reference to one other here I note Parabola invested in a couple of similar period Teletext decoders.

I have been reliably informed (Parabola ) that this decoder has at its core a Texas Instruments "TIFAX" decoder board. A little research finds that these were the first ones which used a Texas Instruments TIFAX (74S262) character generator and were easy to spot because of the curious designs of the 6 and 9 characters.

That is an interesting box Chris, I wonder what the history is on those and if the whole concept fell to bits quite early on. This is because I purchased a Tifax decoder board cheaply from one of the TV mags at a time when most people had still not even heard of Ceefax, maybe 76, or 77.

I wouldn't be surprised if it was Labgear who was selling them off, I don't remember now.However using this board, I made my own set top box with a 17 key keypad and a signal umbilical cord connected between box and TV. I seem to remember that the board needed a line flyback pulse which I borrowed from the line output stage. The wire I used was in the form of a Faraday shield but still had to be kept well away from the video signals or problems would result and therein was the flaw in my design.

Eddie

That certainly looks like a TIfax decoder in the middle ...

Attached is a snapshot of the brand new, boxed, TIFAX decoder board that is part of the Manor Supplies kit.
Courtesy of Parabola

Probably a nice piece of history but something I would be very unlikely to repair, unless you are really interested in reproducing and using teletext.

Certainly is a nice piece of history and I do intend to do my level best to get it going, I would love it to display a few test pages on my PYE. I suppose the only show stopper will be not being able to obtain or feed it teletext, or it not being able to decode due to the issues raised by Jeffrey here.

I've been sent a 23 page document detailing the TIFAX XM11 module that is employed in this ColourText 7026 decoder.

I've loaded it into a new section in the library called, wait for it..... Teletext.

I've not got around to powering the Labgear up yet or seeing if it needs any work as I did not have any way of producing teletext. Now I have a Philips PM5515T at least I have a device that can feed it 5 teletext pages, so I will have to get my finger out.

I made my own set top box with a 17 key keypad and a signal umbilical cord connected between box and TV.

I just downloaded it and that is the document I used to make my Teletext decoder.
I couldn't remember why I needed a 17 key keypad as most keypads were in a 4 X 4 matrix but it tells you what the 17th key was for in there.
I won't reveal the answer in case anyone wants to look it up themselves. 

Eddie

Dammit.. I think I recently junked all the circuits for the I2C PCBs in our Local ATV Repeater in the eighties and nineties..

This used a sync detector and then Teletext generator PCB to draw up several pages of images and text in rotation plus two 'programmable' pages over the air, I hung onto them for years, If I'm lucky I didn't actually strim the pages but the folders are now bare, and I think the software to drive it all is still around somewhere too..

I also wrote various routines and pages for the Two ATV Repeaters in North Wales, so there's a second chance of having the information, busy this weekend but I'll have a look when I get chance.

I hang onto this stuff for donkeys cos "it will be useful someday" I'm sure it will be..

... Now I have a Philips PM5515T at least I have a device that can feed it 5 teletext pages, so I will have to get my finger out ...

I used to have a Philips generator at work - can't remember the model number but very similar - which held a single Teletext page.

I reprogrammed the EPROM to produce a page similar to this (but with a different ident, obviously!) and added a twist of my own ...

There is a paragraph in the Teletext specification that is often over looked which states that rows within a page may be transmitted in any order.

As the generator only output a single row of Teletext data per field, it was rather slow, so I took advantage of this to arrange the rows so that the display started off with the middle row, then expanded alternately up and down to produce a display similar to the old Thames Television ident ...

Only just realised Chris. You obtained this from a facebook friend of mine Al Hine. He lives in Kirkwall, (Orkney Islands). They have a spectacular dump there! All sorts of vintage stuff turns up!

He tries to save as much as possible, But sadly most of it the weather has destroyed and he doesn't have much space..

Hello Chris
I have scanned a copy of “The Service Engineers Guide to Teletext” from Rank Radio International published in 1978 and placed it in the Teletext section of the Library. This book covers the interface of a Tifax decoder to a Rank TV set and how the Teletext system operates. It is quite a big file, about 2.6MB, so if it is too large to keeping the Library please delete it.
Regards Stan.

 

Thanks Stan, much appreciated.

File size is fine 

Another welcome contribution to the Teletext documentation from a fellow VRAT, now available in the library.

Mullard Teletext Decoder technical document.

There was one of these Labgear teletext decoders for sale at the NVCF this year. I also saw one at the McMichael Radio rally in 2010. I was tempted back then as I only had a black and white TV licence and no colour TV. I thought it would be interesting to have the only black and white TV in the world with teletext, but decided against buying it. I knew that analogue TV would be shut down in 2012 in my area, and in the longer term the device would become a large doorstop. In the end, someone gave me a satellite receiver with built-in teletext decoder. It picked up German TV and I experienced German RTL Text in black and white!

This gave me an idea. Teletext is still transmitted on some satellite channels. Apparently RTE in Ireland still broadcasts teletext - Perhaps Michael Watterson could confirm. RTE is broadcast on the Sky Digital satellite platform. You can't officially receive RTE in mainland UK on Sky Digital - it's encrypted and subscriptions are not sold to anyone with an address in England, Scotland or Wales. But apparently the teletext is not encrypted, so if you tune in to RTE on Sky Digital and feed the RF output from the Sky Digibox into the teletext decoder, you will get 'live' teletext, even though you can't see a TV picture!

This must be worth a try. It could give your ancient teletext decoder a new lease of life, at least as long as teletext transmissions continue from satellite.

Yes, the teletext is currently not encrypted. You don't need a Sky box, depending on if you use the Sat box decoder or the TV set decoder. If a generic box re-inserts Teletext then it will work. The Sky box ONLY inserts the Teletext. Almost all generic boxes have a teletext decoder (Sky box hasn't) and can output the pages as video on SCART (or RF if there is a modulator). Few generic boxes bother to re-insert the Teletext into the TV lines.

On Terrestrial (digital and MPEG4 only) they have ended Teletext on RTE1 and RTE2, but it's still on TG4 and TV3.

RTE1 & RTE2 still do have Teletext on Astra. If RTE ever launch Sky Interactive version (uses Open TV) of the Terrestrial MHEG5 based Interactive Text (same standard as Freeview/Freesat) then they will drop Teletext. Currently TG4 and TV3 have no Terrestrial MHEG5 Interactive like RTE.

Saorsat (needs Ka band LNBF and only available parts of IOM. Welsh coast, NI, Cornwall and most of Devon) has no RTE Teletext and currently no TV3 or 3E (as they are too mean to pay) but otherwise is a copy of Terrestrial Saorview.

All on my site here www.saortv.info Big updates on it when I get new hosting.

Yesterday I tried receiving teletext from Sky Digital satellite TV. It worked!

The ingredients:
1 Sky Digital satellite set top box and dish (I used a standard definition box which has a built in modulator)
1 Philips KT3 16" teletext portable TV , donated by ppppenguin (thanks Jeffrey!) see here: viewtopic.php?f=9&t=5341
NO subscription or Sky viewing card needed 😉

Connect the RF output from the Sky box to the TV or teletext decoder. Tune in to UHF channel 68.

Now you need to select RTE 1 or RTE TWO on the Sky box. Unless you have a Sky subscription and viewing card registered in Ireland, these channels do not appear in the TV guide. To add them manually without a subscription, go to the Services / System Setup menu and press Add Channels.
Search for channels on frequency 10744 MHz, Polarity H, symbol rate 22000, FEC 5/6
Store RTE ONE and RTE TWO. To view them, press Services then Other Channels. Again, unless you have a vaild subscription, you won't see a picture, just an on-screen message. This doesn't matter : press the Teletext button on your TV or teletext decoder and hey presto .... Teletext!

It's possible to see the subtitles for the programme being transmitted, even though you can't get any picture or sound. Select teletext page 888.

Further experimentation revealed that Eurosport carries teletext as well, presumably because it also broadcasts to other countries which don't have MHEG. You don't even need to manually add Eurosport to the Sky digibox, just select it from the Sports channels section of the Sky Guide. Again, no subscription is needed to see the teletext, just ignore the on-screen message.

I thought this old TV would never display teletext again, but it just has! Chris's Labgear Teletext decoder should work in exactly the same way. Just connect RF from Sky box to teletext decoder tuned into RF channel 68, then tune the Sky box to RTE One, RTE Two or Eurosport.

Good stuff Hamid. It had me wondering about some of my old Scotch VHS video tapes from the eighties. The old TV advert with the skeleton said they would go on and on for ever or they would give you a replacement tape. I wonder if they were good enough quality to record the text data?

Eddie