@slidertogrid Looks like you've fallen foul of the dreaded JPEG "orientation" flag there!
Have you yet seen a clean composite video output from the IF module?
This project brings back more memories about the Oz Pye teletext set:
The T30 used a Matsushita tuner with a discrete and conventional IF amp and filters, followed by a TCA270. One of the factory operators who did the IF alignments (Gordana Satalic) came to work for me after Marrickville closed down. She said that a normal IF and chroma alignment would be completed in about 2 to 5 minutes but special care was taken with the Teletext sets with 3 or 4 passes used on the IF curve.
Hence the SAW filter would have been a major benefit.
The interface of the TiFax to the T30 small signals panel was very simple - just a handful of discrete transistors on a small PCB with a connector and few wires soldered onto the back of the panel.
I doubt that even 1 of these TVs still exists......
Have you yet seen a clean composite video output from the IF module?
No, the best I've managed is shown below with my scope monitoring the sync at the TBA920, as soon as I switch off and back on again, sync is lost. This is what I mean about knife-edge tuning, I can get good sound, but no picture, rough picture as shown but sound buzzing, or none of the aforementioned and tune to achieve to see garbled teletext. While visually watching the sync via the scope, you can see just how difficult it is physical to get a lock, you have to go super, super slow with ever so tiny adjustments, otherwise it's a flaming mess all the time!
I have replaced the TCA270, and I have even substituted the entire module that hold the TCA270, still the same.
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From what I can remember of the performance of the TiFax I wouldn't expect it to lock to a signal with that much snow.
Can you try battery-boxing the tuner AGC? If that does no good you may have a bad RF amp.
What TV band are you using? Maybe you are trying to tune a image/harmonic?
A further update to this Labgear 7026 resurrection.
You may recall, this Teletext adaptor was a bit of a basket case, remote cut out requiring splicing into the board, faults with the tuner, an i.f. fault and certainly a Tifax fault. The Labgear certainly appeared to be an early version, no screen print and a lot of ic's with their idents scratched off or missing. The Tifax module also being the first release. Despite lots of analysis, I hit a brick wall so the project was shelved with this final statement back in October.
Anyway, before consigning this back to the store room, a little light at the end of the tunnel. There is a chance a Vrat member may, and I stress may, have a spare one I can acquire and in much better condition. Watch this space, but for now, after one week, here endeth the torment of this one.
The other 7026 arrived today, with thanks to @jcdaze for his kind donation. This one is in much better condition and looks to be a later version. All the boards have component silk screen and the Tifax module is issue 7.
Top the original early version, below the later.
Once the box has had a couple of days to acclimatise, I will connect it up to the analogue TV network and see if it can decode my VBIT2 Teletex signal.
If it does, the other test I would like to do is remove the issue 7 Tifax module and install it into the piggyback Teletext board in the Rank AC6333. This will help me ascertain if it's the Rank TIFAX module is at fault, although I did try the other one from the l original labgear and that was faulty too. Of course, I could have two issue 4 boards with faults, or it could be the version incompatibility. By trying the issue 7 I will remove the first two from suspicion, if it too does not work, I have then at least confirmed the fault lies within the Rank Piggyback module or the i.f. board. If it works in the Rank, then I will start a hunt for an issue 7 TIFAX.
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