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Can the RF Modulator be adjusted?

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New to the forum, been an Intellivision fan since childhood, my first system was an Intv 2. I thought it was long gone, but I recently recovered it. That's the short version. It was pretty crusty, but it's mostly cleaned up and working (even before the cleaning) to my amazement.

 

BACKGROUND:

 

Started with an NES RF cable (original missing), picture sucked, but learned on here to replace it with a coax cable. Done. Awesome.

 

Picture got WAY better, I'm stoked, it's totally playable, BUT... I noticed that every graphic has a "shadow" to it's left. You might call it "ghosting", whatever, but it looks to me like the RGB channels are not aligned on the horizonal. Not sure if that's an accurate description of what is actually causing it, but that's how I would describe it.

 

QUESTION:

 

Can the picture be "tuned" on the RF Modulator? There are two little dials or pots recessed into the top, and I'm itching to see what they do, but I thought I'd ask first. I did read about someone tuning the audio channel, is one for that? Are they Vertical and Horizontal hold?

 

Also, if there's nothing I can do to remedy the picture, would the RF Modulators for sale by Left Turn Only fit an Intv 2?

 

Thanks, guys! Love the forum.

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Welcome to the forums!

 

I think the ghosting issue is pretty common - not sure if those trim pots will help w/ that. Surely our more hardware-savvy denizens will chime in soon.

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Welcome to the forums!

 

I think the ghosting issue is pretty common - not sure if those trim pots will help w/ that. Surely our more hardware-savvy denizens will chime in soon.

Thanks!

 

Still haven't touched them, much to my own surprise.

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Yes, welcome to the forums and hopefully the more technically capable will chime in soon to assist. Meanwhile, if you want to learn about weird and obscure and idiotic variations, just ask Steve and I. :)

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Have a look at page 20 of the service manual pdf here. One is definitely an audio adjustment.

https://console5.com/wiki/Intellivision_II

 

I think the rf modulator is the same for all but what you're describing seems to be a common problem.

 

Ah, cool, thanks for that link. It does say that one is for video adjustment, but step 1 under "RF output adjustment" is "connect a frequency counter"... so I assume you need that to do it right.

 

Also tells me that it's not really a vertical/horizontal adjustment as I'd hoped. More like something that gets the right refresh rate or "frequency" to match the TV, which I don't think is the problem here.

 

If anyone has experimented with it, let me (us) know. I might not touch it for now. Will definitely order a fresh RF modulator anyway once I can check if they fit the Inty 2.

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Hi powerpack and welcome to the forum. Could you pls describe a little more your set. TV model ? Are you using the RF switch Box or a ballon (adapter coax to antenna) ? Any rust on the edges ?

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Hi powerpack and welcome to the forum. Could you pls describe a little more your set. TV model ? Are you using the RF switch Box or a ballon (adapter coax to antenna) ? Any rust on the edges ?

 

Sure, TV is a Sanyo CRT, Model # DS13204 (love this little TV)

 

Connected via brand new GE brand coax cable (claims to have "4x the shielding!"), and brand new gold coax-to-RCA adaptor.

 

No rust on the cable/adaptor because that's all brand new. Some surface rusting on the top of the RF modulator.

 

Thanks!

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Pretty sure a small amount of ghosting in the RF signal is completely normal. The ghosting seems to be apparent with composite modded Intellivisions that bypass the RF modulator, so the ghosting seems an inherent quirk of the video signal. I don't expect changing the RF module will improve anything.

 

The only mod I've seen that gets rid of it is an RGB mod.

 

- J

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Pretty sure a small amount of ghosting in the RF signal is completely normal. The ghosting seems to be apparent with composite modded Intellivisions that bypass the RF modulator, so the ghosting seems an inherent quirk of the video signal. I don't expect changing the RF module will improve anything.

 

The only mod I've seen that gets rid of it is an RGB mod.

 

- J

 

Thanks for weighing in. I already ordered one from intvnut, figured it would be good to have a fresh one even if it doesn't make a difference in this case.

 

Also thought I'd try to upload some pics just to make sure we're all talking about the same phenomenon. I don't remember the picture being this off 30 years ago, but you know how that goes ;)

 

It's a good 1/4" off on my tiny 13" TV, so very noticeable. If this is what everybody's looks like (barring the AV mod), then maybe that's as good as it gets for now.

 

Here are the pics, hard to get an accurate pic, neither gives the impression of what it looks like in person (for example, the second Tron guy looks like he has a less pronounced ghost/shadow, but every object on the screen has it). Added a line next to the "D" to show how far it goes. Theres a Red area and then a darker (blue?) area.

 

INTV_picDrift1_zpsuxzcsk18.jpg

 

INTV_picDrift2_zpsxhxwse9s.jpg

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Overall, this isn't too awful. The worst problem I tend to see is noise in the picture - especially when sound effects play - or a generally snowy picture.

 

Sometimes old-school settings like brightness and contrast can have a big influence on this kind of thing, too. As a callow yoot, I recall spending a lot of time tinkering with a bunch of settings on the TV to try to get things to look like they did in the old color manuals. Never could get a decent brown, which we now understand was apparently not possible. :P

 

It may well turn out that the only thing you'll do better with would be the RGB mod.

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That's weird , but not so much weird . It's most difficult to have this problems on CRT than on LED TV sets. Can be a lot of things , but start by the basics. As intvsteve said try first to make some adjustments on the tv set , try to find if your TV has a channel fine tuning , most of TV set has , put your intv in ch3 or ch4 , select fine tuning and goes up or down and see if gets better. Try with color and brightness too. If none of this work , is it possible to find a regular RCA cable, a switchbox and a pipe ( a 300 to 75 ohms adapter) to check if works ? Maybe some impedance balance either. Last but not least , if you twist lightly the cable edge on the console , does it flicks or get any response on the TV ? I have to remove the entire RF module once because the output connector was a little bit loose and I have to re-sold it to eliminate some problems.
Hope this helps ...

 

 

 

Thanks for weighing in. I already ordered one from intvnut, figured it would be good to have a fresh one even if it doesn't make a difference in this case.

 

Also thought I'd try to upload some pics just to make sure we're all talking about the same phenomenon. I don't remember the picture being this off 30 years ago, but you know how that goes ;)

 

It's a good 1/4" off on my tiny 13" TV, so very noticeable. If this is what everybody's looks like (barring the AV mod), then maybe that's as good as it gets for now.

 

Here are the pics, hard to get an accurate pic, neither gives the impression of what it looks like in person (for example, the second Tron guy looks like he has a less pronounced ghost/shadow, but every object on the screen has it). Added a line next to the "D" to show how far it goes. Theres a Red area and then a darker (blue?) area.

 

INTV_picDrift1_zpsuxzcsk18.jpg

 

INTV_picDrift2_zpsxhxwse9s.jpg

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That's weird , but not so much weird . It's most difficult to have this problems on CRT than on LED TV sets. Can be a lot of things , but start by the basics. As intvsteve said try first to make some adjustments on the tv set , try to find if your TV has a channel fine tuning , most of TV set has , put your intv in ch3 or ch4 , select fine tuning and goes up or down and see if gets better. Try with color and brightness too. If none of this work , is it possible to find a regular RCA cable, a switchbox and a pipe ( a 300 to 75 ohms adapter) to check if works ? Maybe some impedance balance either. Last but not least , if you twist lightly the cable edge on the console , does it flicks or get any response on the TV ? I have to remove the entire RF module once because the output connector was a little bit loose and I have to re-sold it to eliminate some problems.

Hope this helps ...

 

 

 

None of the TV settings make a difference in the effect. And the picture doesn't respond in any way when I twist the coax cable/connector.

 

I don't know what you mean by a switchbox and a pipe. Sounds like you're referring to a resistor?

 

I'll keep tinkering with it, but right now I'm just psyched to be playing the INTV 2 again.

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Hi Powerpak, here goes the switchbox and the pipe: vidadapt1.jpg

It was a classic way to connect through the VCR in the 80's . If you bend the cable and nothing happens , you Intv RF output is in good shape. So, probably is something related to unbalanced impedance. If could find the switchbox you could eliminate this too.

 

 

None of the TV settings make a difference in the effect. And the picture doesn't respond in any way when I twist the coax cable/connector.

 

I don't know what you mean by a switchbox and a pipe. Sounds like you're referring to a resistor?

 

I'll keep tinkering with it, but right now I'm just psyched to be playing the INTV 2 again.

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Dear lord, never use a switchbox. Just get an RCA-coax adaptor (better still, when you can find them, a dedicated cable designed for this). Switchboxes invariably make things worse in all aspects.

 

Ghosting (and its cousin, color bleed) is inherent to using an RF signal. We only notice it so much because "modern" CRTs have such better picture quality than they did in 1981.

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The color signal for NTSC video has a much lower horizontal resolution than the luminescence (black & white) signal, so seeing color bleed is pretty normal. It isn't too noticeable in normal camera-generated images, but more visibly affects sharp transitions, like the digital art from video game systems. This is why analog video aficionados liked S-Video -- it had a higher bandwidth path for color information, which let it be more accurately reproduced.

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