Hey all,

This is a follow-up to my post here: https://vintage-radio.com.au/default.asp?f=6&th=341 and a bit more of a Q&A into TVs and why this thing isn't working. Ideally, I'd like for it to work one day, but if what I'm asking seems complicated or the solution is more, 'throw it out and get a new one', those answers would also be appreciated if you could give a reason as to why.

This is more so to learn more about the tech with a friend of mine who's more knowledgeable on the subject (currently studying electrical engineering or something at Uni), as well as a bit of a personal "I want this thing to work because it's really really cool to have in the house, and it just seems like an interesting project y'know"? We're already well aware of what safety precautions we should be taking, so far nobody's blown up at least.

Just for reference, I have scans of the schematics and whatever came stapled to the inside of this TV stored on my OneDrive here: https://1drv.ms/u/s!Ak60DwOwHkV7m5ssQDt75MaRm0l68Q?e=5wYD6q

So basically, we've opened it up and dusted it with a bit of compressed air. Powering it on shows the tubes all glowing, and sending a signal with a HackRF and some fancy software magic (https://github.com/fsphil/hacktv) gives us a solid audio and video signal. The problem is displaying that signal.

Using another TV, broadcasting with the HackRF to Channel 0 at 46.25MHz gives us a clear video with audio. Great! The signal we're sending is ok! It's just that hooking that signal up to the TV we're working on gives us no picture, the audio comes through great. Interestingly though, without a signal we can see static on the screen.

Only when we are tuned into a station that has a signal going to it, do we have no picture and only audio. Otherwise it's static with your good ol' white noise. What could be causing this, and we could we do to possibly resolve the issues?

Any and all info would be great! If you think this is out of the scope of two young engineering students, then please if anyone here can recommend someone around Perth/Western Australia who can lend a hand, that'd be great!

Thanks,
Oliver.

This would be a great project for a couple of EE students! Sounds like the vacuum tube part of it is working just fine, which leaves you with the more familiar to you solid state technology to work on.

I know the series 11 well, I have one that had numerous faults caused mainly by mice peeing in the thick coating of dust on the PCB! Rotted the legs of most of the transistors away!

I posted the story here:

https://antiqueradios.com/forums/viewtopic.php?f=3&t=414063

I hope your Series 11 is a later production that has all Philips transistors (in TO18 cans) and not the little rectangular shaped Anodeon transistors. If you have these and you want your TV to be reliable, you may have to consider changing out all of them.

It sounds like the brightness is set too low and the video signal is biassing the CRT to cut-off. Is it set to max setting? If so and it's still a bit dark, suspect firstly the dropper resistor to the brightness pot itself, then the resistors that supply the G2 voltage to the CRT. G2 should measure about 450 volts from memory.

If all this checks out, what is the collector voltage on the video output transistor, with and without signal?

Your signal may be too strong for this TV. Adjusting the AGC pot and/or attenuating the signal may help.

My email is open...

Remember when later Astor TVs said "Colour Compatible" on the back cover (meaning they had a 4.43 luminance notch filter.) May have been better to snip it out at that time. And while you're at it snip out the audio de-emphasis cap so that you can compensate for the hf roll-off of the cheap speaker.

I just looked at the schematic, it doesn't have a chroma trap. Did that Astor feature come before or after this TV?

I don't recall seeing any B&W TVs here with chroma traps. Probably because very few were made here after the start of colour.

Most B&W TVs had sound traps on 5.5MHz and the skirts of these were sufficiently wide to reduce any 4.43MHz that might be present.

I suspect the "colour compatible" assertion was more marketing hype than real. It was probably related to some improvement in sound performance to go with the reduced sound carrier level WRT vision that was introduced prior to the start of colour transmissions. Astor apparently also distributed a colour signal around the factory - "All Astor TVs are tested on Colour!"

In that post I mentioned above you can see the chroma from an NTSC signal on the close-up near the end of the post. It came from a region 1 DVD,

It would have been after the decision to adopt PAL but before transmissions.
I just searched it and someone has pic of Astor back cover with sticker.
It would be interesting to read that fine print on sticker!
here's pic. facebook.com/photo/?fbid=1100347980609321&set=pcb.1100348270609292

Here's an Ad from 1969 claiming "TV is tested against PAL MkIII signal" and its "compatibility will mean higher trade-in value later!"

facebook.com/photo/?fbid=412485636062229&set=pb.100071264837449.-2207520000.&locale=da_DK

...the split screen image in the Ad implies improved gamma/greyscale from elimination of chroma artefact, if not with a 4.43 notch, then by rolling off video after 4 megs?

What Astor and other makers were battling with is the tendency at that time to get your old TV overhauled (new CRT, paper caps replaced) instead of buying a new one with colour so close. I was in the TV service industry at the time and that's what they got the apprentices to do - replace all the paper caps in 10+ year old TVs. We were certainly busy doing just that at the time.

So it comes down to - how do you mount a convincing argument in 1969 for buying a new B&W TV? There was very little technically that you could claim. The Astor Series 11 was a very basic TV design - no horizontal / EHT stabilisation for example, that most other contemporary designs did have.

So what are we looking at here? Bovine excrement I'd suggest.....

Because were not the world's colour systems already "guaranteed" to be backwardly compatible?
I wonder how many Astor buyers - noting the Colour sticker - thought they'd spring to rainbow glory on C-day

But I wonder about the multi standard sets that later hit Aust if they also included a 3.58 NTSC luminance filter?

Yes many of the later models had digital comb filters. These made sources like NTSC laser discs display a decent picture.

Comb filters were something the designers of NTSC had anticipated. The harmonics of the colour signal fall in between the luminance harmonics, but comb filters were wildly impractical at the time. We were stuck with relatively crude bandpass and notch filters.

I heard either BBC or ITV made a price-no-object standards converter in the 70s that comb filtered PAL, probably using a framestore or a multi-line FIFO store for digital processing.

IF you saw "The Muppet Show" in the US, you've seen the results. it was shot on PAL in the UK and went through that standards converter for the US market.