Teletext Adapter Service Manual

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maniacminer
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Teletext Adapter Service Manual

Post by maniacminer » Sun Oct 06, 2019 12:34 am

Hi guys,

Does anyone by any chance have a copy of the Teletext Adapter Service Manual?

I have found Service Manuals for every other Acorn product except this one and this is the most complicated wedge!

The back story:

I got a 1st generation cheese wedge adapter in the pile of stuff I got.

A quick look through it with the 'scope shows that it does tune, but the auto-tuning is fluttering around, perhaps the IF needs alignment (hidden in the huge metal box) Using the tuning mode of the TFS 1.0 ROM I get a strong signal that comes and goes about every two seconds. If I ignore the tuning meter and just watch the Teletext on the screen, I am able to get a reasonable signal and I get some Teletext pages from good old TEEFAX (I have been using that on my old Sony TV for about a year now with a Pi)

To drive the wedge, I took the UHF modulator from one of the dead Electrons and put that on a piece of Veroboard with some bypass capacitors, I then checked the signal on the TV and the Teletext is perfect - the actual video display from the Pi is horrid, but it always has been on composite #-o

I have attached a screenshot of the BBC Micro with the TFS ROM installed displaying the home page of TEEFAX, that's the best I've managed to get so far.

Any help would be greatly appreciated :D
Attachments
teletext.jpg
Last edited by maniacminer on Thu Oct 10, 2019 10:21 am, edited 1 time in total.

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Re: Teletext Adapter Service Manual

Post by guesser » Sun Oct 06, 2019 9:58 am

I assume you've got the schematic? I would also like a copy of the service manual for future reference if someone has it.

I had a similar issue with my TTX2000S for the Speccy where the tuning wouldn't stay locked on. That turned out to be a bad ceramic cap near the tuner. I only found it by probing around all over the circuit with the scope to find where the tuning voltage was going wrong.
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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Re: Teletext Adapter Service Manual

Post by maniacminer » Mon Oct 07, 2019 4:43 pm

guesser wrote:
Sun Oct 06, 2019 9:58 am
I assume you've got the schematic? I would also like a copy of the service manual for future reference if someone has it.

I had a similar issue with my TTX2000S for the Speccy where the tuning wouldn't stay locked on. That turned out to be a bad ceramic cap near the tuner. I only found it by probing around all over the circuit with the scope to find where the tuning voltage was going wrong.
Yes, thanks, I have the schematic and that helps a little bit. I could see the AFC moving the signal around trying to track the input. I am going to look at another modulator, I have a feeling the Astec UHF modulator from one of the dead Electrons is crap anyway, especially as it is drifting around in frequency, something the TV is very forgiving of, but the wedge is very, very slow at adjusting to change. The tuning pots needed cleaning as well, some contact cleaner and then a pin-head sized blob of carbon contact grease and the pots are behaving themselves now :)

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Re: Teletext Adapter Service Manual

Post by IanS » Mon Oct 07, 2019 6:27 pm

maniacminer wrote:
Mon Oct 07, 2019 4:43 pm
Yes, thanks, I have the schematic and that helps a little bit.
Can you not bypass the tuner and feed the video in directly to LK3?

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Re: Teletext Adapter Service Manual

Post by guesser » Mon Oct 07, 2019 7:48 pm

I bought some New Old Stock modulators from Germany to build my "Teletext Insertomatic 4000". They're ALPS MDLP3W104A which are "modern" electronically tuned units which I hooked up to the Raspberry Pi I²C pins via a mosfet level shifter. They need a 30 volt tuning supply which I generate with a slightly modified biglive.com "joule thief" and a KA33VTA voltage stabilizer. I have a write-up of the whole Insertomatic here: https://zxnet.co.uk/teletext/insertomatic/

Alternatively you could just bypass the tuner as Ian suggests :lol:

Edit to add:
More practically, you can buy basically the same thing in a ready made mains powered unit from all the usual places. I just wanted to integrate four instances into one box so it made sense to build it up from scratch. The ability to tune them from the Pi was a bonus but not really necessary :)
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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Re: Teletext Adapter Service Manual

Post by 1024MAK » Mon Oct 07, 2019 8:14 pm

The ASTEC UM1233 UHF Modulators are well known to me for their ability to drift as their temperature changes. I have a TV set up so that six channels are all tuned to about channel 36, so when using or testing a computer that uses a ASTEC UM1233 UHF Modulator, I can channel hop as the modulator output frequency drips...

Mark

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Re: Teletext Adapter Service Manual

Post by maniacminer » Mon Oct 07, 2019 8:55 pm

IanS wrote:
Mon Oct 07, 2019 6:27 pm
maniacminer wrote:
Mon Oct 07, 2019 4:43 pm
Yes, thanks, I have the schematic and that helps a little bit.
Can you not bypass the tuner and feed the video in directly to LK3?
Thanks for the info, I had a go today, worked my way through the schematic today and put the video out straight into the SAA5030 via a small capacitor, but I still get "Bad data" at the bottom of every page, despite there being no visible error. #-o I tried another modulator from another dead Electron and the signal doesn't wander anywhere near as much, but the signal is still very noisy.

I am now thinking I've been caught out by the crap modulator and the out of date TFS1.0 ROM that doesn't understand modern Teletext, for example, I don't have the Fastext links at the bottom.

Time to dump this ROM and move onto ATS! 8) It is amazing to see my middle-aged Sony TV able to read the entire magazine, so every page is immediately available :)

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Re: Teletext Adapter Service Manual

Post by maniacminer » Mon Oct 07, 2019 9:08 pm

guesser wrote:
Mon Oct 07, 2019 7:48 pm
I bought some New Old Stock modulators from Germany to build my "Teletext Insertomatic 4000". They're ALPS MDLP3W104A which are "modern" electronically tuned units which I hooked up to the Raspberry Pi I²C pins via a mosfet level shifter. They need a 30 volt tuning supply which I generate with a slightly modified biglive.com "joule thief" and a KA33VTA voltage stabilizer. I have a write-up of the whole Insertomatic here: https://zxnet.co.uk/teletext/insertomatic/

Alternatively you could just bypass the tuner as Ian suggests :lol:

Edit to add:
More practically, you can buy basically the same thing in a ready made mains powered unit from all the usual places. I just wanted to integrate four instances into one box so it made sense to build it up from scratch. The ability to tune them from the Pi was a bonus but not really necessary :)
Yup, I did just that :) The Block Party sounds fun! Interesting build, I'm surprised you didn't need a fan in that box :)

I've managed to find a couple of mains powered modulators for £5 each, "Mercury ILS102" they use 12V and use a digital tuning control. Hopefully, I'll have more luck! Just for laughs, I'll try one on a Beeb, as the Beeb UHF is horrible, even by 80s computer standards.

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Re: Teletext Adapter Service Manual

Post by maniacminer » Mon Oct 07, 2019 9:12 pm

1024MAK wrote:
Mon Oct 07, 2019 8:14 pm
The ASTEC UM1233 UHF Modulators are well known to me for their ability to drift as their temperature changes. I have a TV set up so that six channels are all tuned to about channel 36, so when using or testing a computer that uses a ASTEC UM1233 UHF Modulator, I can channel hop as the modulator output frequency drips...

Mark
Yikes! I never realised that these Astec modulators were so poor. I guess I've been lucky to never have had to rely on it for using the computer. We either had mono composite video into a green screen or RGB into a monitor. I don't remember the Spectrum, C64, Amiga, Sega etc. being this bad (could be faulty memory though!) I was just looking at those Electrons and wondering what I was going to do with them, then I remembered they had the same UHF modulator as the Beeb and if it was in the Beeb, then it had to be good... (did Acorn have shares in Microvitec?) \:D/

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Re: Teletext Adapter Service Manual

Post by guesser » Mon Oct 07, 2019 9:29 pm

maniacminer wrote:
Mon Oct 07, 2019 9:08 pm
I'm surprised you didn't need a fan in that box :)
I'm surprised it coped at the "Chunky Fringe" in Harrow this July, the room we were in was sweltering. It's running very cool right now as it's downstairs in the workshop with the radiator turned off and the door closed. The Pi 3 reports it's currently running at 51.5°C :)

I notice you mention you're using the TFS ROM. I'd recommend blowing an ATS ROM if you have the kit to do so, it's far better, and will let you use the "new" telesoftware system which is what Teefax will be supporting if I ever get around to doing anything with it. :oops:
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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Re: Teletext Adapter Service Manual

Post by maniacminer » Mon Oct 07, 2019 10:37 pm

guesser wrote:
Mon Oct 07, 2019 9:29 pm
maniacminer wrote:
Mon Oct 07, 2019 9:08 pm
I'm surprised you didn't need a fan in that box :)
I'm surprised it coped at the "Chunky Fringe" in Harrow this July, the room we were in was sweltering. It's running very cool right now as it's downstairs in the workshop with the radiator turned off and the door closed. The Pi 3 reports it's currently running at 51.5°C :)

I notice you mention you're using the TFS ROM. I'd recommend blowing an ATS ROM if you have the kit to do so, it's far better, and will let you use the "new" telesoftware system which is what Teefax will be supporting if I ever get around to doing anything with it. :oops:
LOL Telesoftware, that brings back memories (no particularly good ones) #-o but it would be fun to see some bits of demoware for us to download.

Yup, I did exactly that, I burnt an ATS2.5 ROM (I found a pile of old BBC ROMS, Wordwise+ etc. that I sliced the sticker off and cleaned the quartz window and rejuvenated the pins with a PCB pen and leg straightener tool) and it works perfectly! :D

I had a good read through this https://heyrick.eu/software/ttx/ttxohiw.html and downloaded the SAA5030 datasheet (the Acorn wedge is a carbon copy) then spent some time on the scope replaced a couple of capacitors and got a nicer looking signal. Now the pages come around just as quickly as the old Sony TV and the clock is perfectly synchronised, no missing second and double speed second tick, no corruption of any kind.

There was a rabbit hole in that wedge, Alice :shock:

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Re: Teletext Adapter Service Manual

Post by 1024MAK » Mon Oct 07, 2019 10:40 pm

maniacminer wrote:
Mon Oct 07, 2019 9:12 pm
Yikes! I never realised that these Astec modulators were so poor. I guess I've been lucky to never have had to rely on it for using the computer. We either had mono composite video into a green screen or RGB into a monitor. I don't remember the Spectrum, C64, Amiga, Sega etc. being this bad (could be faulty memory though!) I was just looking at those Electrons and wondering what I was going to do with them, then I remembered they had the same UHF modulator as the Beeb and if it was in the Beeb, then it had to be good... (did Acorn have shares in Microvitec?) \:D/
They were used in a lot of home computers in the 1980s, including (off the top of my head) ZX80, ZX81, ZX Spectrum, Acorn Atom, Acorn Electron, BBC Micro and so on...
Some like the Dragon 32 and Dragon 64, used a different version. For example the Memotech MTX500 and MTX512 used the Astec 1286 modulator.

But you have to remember that they are analogue technology. And the televisions were also analogue technology. Because the demodulator in the TV also drifted, the automatic frequency control in (most) TVs could stay locked on. Also the analogue TVs were more forgiving. Well, unless you were trying to get teletext, in which case not all TVs were as forgiving as others...

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Re: Teletext Adapter Service Manual

Post by guesser » Mon Oct 07, 2019 11:28 pm

maniacminer wrote:
Mon Oct 07, 2019 10:37 pm
Yup, I did exactly that, I burnt an ATS2.5 ROM (I found a pile of old BBC ROMS, Wordwise+ etc. that I sliced the sticker off and cleaned the quartz window and rejuvenated the pins with a PCB pen and leg straightener tool) and it works perfectly! :D
There's an ATS 3.0 which the one beebem ships. I don't know what the difference are (though I suspect articles all about it were broadcast on Ceefax telesoftware!)

If you've got a blank disk inserted and Teefax up and running in ATS, hit F5 and you should get treated to an exciting demonstration of your microcomputer's ability :lol:
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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Re: Teletext Adapter Service Manual

Post by maniacminer » Wed Oct 09, 2019 10:01 pm

guesser wrote:
Mon Oct 07, 2019 11:28 pm
maniacminer wrote:
Mon Oct 07, 2019 10:37 pm
Yup, I did exactly that, I burnt an ATS2.5 ROM (I found a pile of old BBC ROMS, Wordwise+ etc. that I sliced the sticker off and cleaned the quartz window and rejuvenated the pins with a PCB pen and leg straightener tool) and it works perfectly! :D
There's an ATS 3.0 which the one beebem ships. I don't know what the difference are (though I suspect articles all about it were broadcast on Ceefax telesoftware!)

If you've got a blank disk inserted and Teefax up and running in ATS, hit F5 and you should get treated to an exciting demonstration of your microcomputer's ability :lol:
Thanks for that, unfortunately the only ATS 3.0 I could find was for the Morley or Acorn Advanced Teletext Adapter and both of those use the User Port. However, I am happy to report, pressing F5 and downloading the Telesoftware from the catalogue worked fine. It'd be fun to put some simple BASIC games like Hangman, Hi-Lo etc. on there. I suspect it'll take quite a while to download anything substantial :-

The "digital" UHF modulators arrived and I can now view perfect Teletext via the UHF on the Teletext Adapter and the TV. I took a (rather dodgy) photo of the screen of the old Sony TV for a comparison. The Astec modulator is atrocious in comparison. I'll pop the Beeb apart and make S38 and give the Beeb a go on UHF, just for sake of a nostalgia never endured 8)

I should find myself a new keystrip, the TFS1.0 keystrip ain't much use #-o
Attachments
Electron UHF Modulator output.jpg
Electron UHF Modulator output
Electron UHF Modulator Teletext.jpg
Teletext on the old Sony TV from the Electron UHF Modulator
Mercury Modulator output.jpg
Mercury UHF Modulator output
Mercury Modulator Teletext.jpg
Teletext on the old Sony TV from the Mercury UHF Modulator
First Telesoftware.jpg
My first bit of Telesoftware :D
Last edited by maniacminer on Thu Oct 10, 2019 10:19 am, edited 1 time in total.

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Re: Teletext Adapter Service Manual

Post by guesser » Wed Oct 09, 2019 10:24 pm

maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
Thanks for that, unfortunately the only ATS 3.0 I could find was for the Morley or Acorn Advanced Teletext Adapter and both of those use the User Port.
As I say, the one that ships with BeebEm is the correct ROM for the cheese wedge. As far as I'm aware the "Teletext System" and "Advanced Teletext System" are the same thing. It's just an improved ROM for the same ANE01 interface.
maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
However, I am happy to report, pressing F5 and downloading the Telesoftware from the catalogue worked fine. It'd be fun to put some simple BASIC games like Hangman, Hi-Lo etc. on there. I suspect it'll take quite a while to download anything substantial :-
It depends how fast I set it to transmit the pages. Obviously you have to trade off download speed for not slowing the service down for everyone else, but telesoftware can be spewed at one page per second if desired :)
I've yet to write any nice scripts to generate the downloads, the example program and telesoftware catalog were hand assembled. Somebody more competent with BBC BASIC than me might like to write one that runs natively on a Beeb. I could well imagine that the BBC prepared the files that way - it would be neat if the disks survived and turned up!
maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
I should find myself a new keystrip, the TFS1.0 keystrip ain't much use #-o
I've recreated the ATS keystrip from a scan somebody kindly provided on here https://zxnet.co.uk/teletext/documents/ ... ystrip.pdf
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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Re: Teletext Adapter Service Manual

Post by maniacminer » Thu Oct 10, 2019 1:32 am

guesser wrote:
Wed Oct 09, 2019 10:24 pm
maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
Thanks for that, unfortunately the only ATS 3.0 I could find was for the Morley or Acorn Advanced Teletext Adapter and both of those use the User Port.
As I say, the one that ships with BeebEm is the correct ROM for the cheese wedge. As far as I'm aware the "Teletext System" and "Advanced Teletext System" are the same thing. It's just an improved ROM for the same ANE01 interface.
I've stuck that ROM image "ATS 3.0.1" onto an EPROM and I'll give it a go. Thanks for the tip.
guesser wrote:
Wed Oct 09, 2019 10:24 pm
maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
However, I am happy to report, pressing F5 and downloading the Telesoftware from the catalogue worked fine. It'd be fun to put some simple BASIC games like Hangman, Hi-Lo etc. on there. I suspect it'll take quite a while to download anything substantial :-
It depends how fast I set it to transmit the pages. Obviously you have to trade off download speed for not slowing the service down for everyone else, but telesoftware can be spewed at one page per second if desired :)
I've yet to write any nice scripts to generate the downloads, the example program and telesoftware catalog were hand assembled. Somebody more competent with BBC BASIC than me might like to write one that runs natively on a Beeb. I could well imagine that the BBC prepared the files that way - it would be neat if the disks survived and turned up!
I have some discs in the huge pile of stuff, maybe the guy managed to download some of the programs? Is there a list of programs out there?
guesser wrote:
Wed Oct 09, 2019 10:24 pm
maniacminer wrote:
Wed Oct 09, 2019 10:01 pm
I should find myself a new keystrip, the TFS1.0 keystrip ain't much use #-o
I've recreated the ATS keystrip from a scan somebody kindly provided on here https://zxnet.co.uk/teletext/documents/ ... ystrip.pdf
Cool, thanks for the link to the keystrip, I've just printed it out and put it on the Master.

The ROM works!
Attachments
master with keystrip.jpg
Master with new keystrip fitted
programming eprom.jpg
Programming ATS3.0.1 (took ages for some reason)
help.jpg
*HELP and yup, it works! yay!

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Re: Teletext Adapter Service Manual

Post by guesser » Thu Oct 10, 2019 12:19 pm

:D

I was meaning maybe the software the BBC used to prepare the downloads survived somewhere.

G7JJF has some disk images of telesoftware download archives.
A web based teletext editor which can export as Mode 7 screen memory: https://zxnet.co.uk/teletext/editor
Join the Teletext Discord for teletext chat.

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