I read the article last night and thought the same thing too. I am going to build the chroma filter descibed in the article and connect it to the Jaycar modulator to see if that makes a improvement.

Also, I did sent some photos the other day of my TV to be uploaded here. Maybe they were overlooked or forgotten?

Cheers.

You might also want to try taking the video feed for your RF modulator from the "Y" component output of the DVD player. This is a luminance/sync signal only (ie composite video) without the chroma (colour) information in it. i.e. it is a pure B&W video signal. This will save having to play with chroma traps and the loss of video bandwidth that they cause.

Using luminance only is the cleanest solution.

If your source device doesn't have a composite Y output, you can also obtain this signal from a S-VIDEO output - there are 2 pins for the luma signal and ground, two pins for chroma. Check pinout for the particular socket you have available.

Maven

I have an Astor Royal 23 inch console, and I am looking to get it restored, so anyone got a resto guy I could go to? I'm in the Maitland/Cessnock area

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"I'd rather have a CRT than nothing" - me
"people just throw working CRTs out, it is NOT FUNNY!" -me

I tried TV Collectors suggestion of plugging the RF modulator into the "Y" component output of the DVD player. There was very little difference.

What I'm trying to achieve is to reduce the hum/buzz that comes when there is a excess of white on the screen. Is there any adjustment on the TV itself to reduce this noise?

Maven, both the DVD player & STB have a S-VIDEO socket as well as the RCA connections.

Is it possible for a way to connect a PC's VGA output into a old TV via the RF modulator? My program source (B/W of course) is limited to a few DVD's at the moment, but there are plenty of classic clips on Youtube.

Cheers.

You can get a VGA to composite converter box on ebay for about $15 to 20 dollars i'll post the link to one: http://www.ebay.com.au/itm/Composite-TV-AV-S-Video-To-VGA-PC-Converter-Monitor-Adapter-Switch-Box-/221207261081....

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"I'd rather have a CRT than nothing" - me
"people just throw working CRTs out, it is NOT FUNNY!" -me

Nathan, the adapter you have linked to goes the opposite direction from what Monochrome wants.

VGA has no separate luminance channel, so any external adapter would have to sum/average the red, blue and green channels into a composite signal or a synthesised luminance signal, which would not save you any steps.

S-video is an improvement over single-channel composite device output solely by the fact that it separates chroma from luminance. So it is not as good as VGA or DVI for colour separation, but it is better than VGA for luminance separation.

DVD encoding is MPEG-2 and should put out a pure monochrome signal if correctly encoded and decoded.

It's a puzzle that you don't get a clean signal from the Y channel of the component output. It ought to be the same as what you would get from the luma signal of S-Video, though S-video might turn out to be a better impedance match for your modulator. You should find the luma signal on pins 3 and 1(gnd) on a 4-pin s-video, and the pins in the same position on the 7-pin version (the extra 3 pins are composite signals).

I wonder if you have an EMI problem? Double-insulated devices often have poorly-filtered switchmode power supplies that put a lot of noise on the ground plane including the shielding of connector cables. You might pick that up on an AM radio.

Maven

I'm not sure what sort of RF converter you are using so I can't comment on its quality but the majority of generic converters do not produce a particularly good RF signal that meets broadcast standards!

Modern sets are very forgiving of poor RF signals but old TV's rely on the signal abiding by certain standards. You've noticed that the TV is fine with on air signals but is poor with the converter.

There are some possible solutions. First is that the TV may be getting overloaded by the signal from the converter. Try feeding a weaker signal to the TV.
The other is to adjust the contrast pre-set control on the chassis. This is an AGC (automatic gain control) adjustment and it will reduce to gain of the RF/IF stages. Note that this will also mean the on-air signals will be weaker as well so this is may not be the best solution.

Thanks for the description of the repair work, Monochrome, it's helpful. I'm back at work on my Astor Plymouth, which has an earlier (4A) version of the same circuit and a similar vertical problem.