Unwanted vertical lines on the VIC's TV picture

RobertK · Post by **RobertK** » Thu Nov 18, 2004 10:04 am

Hi folks,

I'm a new owner of a VIC from the older series (with the 2-prong power pack), and I'm using an RF Modulator from a newer VIC, which basically produces a very sharp picture on my TV. I had already noticed some faint vertical lines on the cyan border of the VIC's picture, which first didn't bother me (these lines are somewhat normal among CBM computers, my C128 also has them). But now that I have a working datasette, I've tried out a few games and found out that on certain background colours (especially orange) those vertical lines are distinctly visible and VERY annoying.

I remember that in the 80s I played Quadrant on my newer-generation VIC (with the DIN-power pack), and there the background was basically a solid orange-coloured area. But on my current machine, these lines make my favourite game look rather ugly so that I don't want to play it anymore

I have already tried to adjust the picture settings on my TV - reducing the contrast does help a little, but then the picture does not really look good anymore and the problem is still there anyway.

A few questions:

1) Would it help to build the Cinch-cable adaptor? Those lines would probably not entirely disappear, but would they become less visible?
I have to note that I also own a C128 using a Sanyo monitor via separate-signal connection, and there are also some faint vertical lines visible.

2) Would it help to use an original RF modulator from the older VIC series? (I even have one, but it's connector is broken, so I would have to reconstruct it.) I.e. is it a problem if I use an old VIC with a new RF modulator (or vice versa)?

3) Where exactly is the cause for this problem? Is it in the RF modulator or in the VIC? Would it make sense to try any other VIC RF modulator? I.e. could it be that my RF modulator is simply a little "broken"?

4) Is there anything else that I could do to get rid of those vertical lines?

Thanks for all your help,

Robert

Post by **Jeff-20** » Fri Nov 19, 2004 7:40 pm

I have nothing helpful to say. However, I have noticed newer TVs do not work well with older game systems. Last night, we had an Atari party. I couldn't get the Atari 2600 to work with my TV. The problem was resolved with a direct connection. For some reason, it wouldn't work routed through the VCR or other AV switchs. The signal just doesn't seem strong enough. Turbo Grafx, VIC 20 and other systems worked just fine. Go figure.

Boray · Post by **Boray** » Sun Nov 21, 2004 7:47 am

I've had the opposite experiance. My old vic has a really good display, but my two newer (din type) vics has a worse display with the vertical lines much more visible.

Read:
http://sleepingelephant.com/ipw-web/bul ... .php?t=207

http://sleepingelephant.com/ipw-web/bul ... 2&start=16

http://sleepingelephant.com/ipw-web/bul ... .php?t=184

Btw, I would guess that older/newer rf-modulators works the same... But I don't know... Because there are some differences on the video plug. On some it's a low and a high video signal. On others there is only a high (strong) video signal on both pins...:
http://sleepingelephant.com/ipw-web/bul ... 8&start=20

/Anders

Boray · Post by **Boray** » Sun Nov 21, 2004 8:00 am

It is the computer that makes the lines so the RF-modulator doesn't have anything to do with it, except for maybe making the picture a little unsharp so that the lines doesn't show that much...

/Anders

Bacon · Post by **Bacon** » Fri Nov 26, 2004 1:23 am

I have an old-style and a new-style VIC, and none of them displays any vertical lines. I use the direct video out to a 1084S monitor. I can't use the RF signal from my vintage computers with my modern TV, so I don't know if there would be any vertical lines there.

All my C128s show vertical lines, but that's part of the "upgraded" VIC-II chip in the 128. None of my C64s or Plus/4s has this problem, so I wouldn't say that it's normal among Commodores.

Boray · Post by **Boray** » Sun Nov 28, 2004 5:26 am

Mabe it has to do with the monitor as well... My amiga displays vertical lines on my SyncMaster monitor, but with a M1438S, there is none using the same screenmode (DblNTSC).

I have three C128. One of them has a very good display without lines but the other two has very visible lines (My C128D included). I think my C64 has faint lines as well...

/Anders

Boray · Post by **Boray** » Mon Nov 29, 2004 5:47 am

Correction: ALL my C128s have the lines. I also checked my C64 (made in 1987), and it also has the lines, but very faint. About as much as my old vic-20. The lines are most visible on the C128s.

/Anders

RobertK · Post by **RobertK** » Tue Jan 11, 2005 8:34 am

In the meantime, I've tried a few things...

First, I've built the the Cinch cable adaptor, and with this, the picture is a little sharper and - as expected - the lines are even more visible. BTW, although my VIC is a 2-prong one, I've connected the "Low" Pin (Boray: I simply forgot about what you had told me...), but it works with that one.

I've also tried to connect the VIC to my parents' TV set (manufactured in 1987) via RF adaptor, and there the lines are indeed not as annoying as on my modern TV. They are still visible, but not as much that playing Quadrant wouldn't be fun. I believe the reason is that the picture of that old TV set is less sharp, although you normally don't see much difference.

Then I've used the Cinch cable to connect the VIC to an old Sanyo C64 monitor. It produces a rather blurry picture from the composite signal (with separate signal connection from my C128, its picture is very sharp). There, the lines are even less disturbing, although still visible. On yellow background however, they are still there, but on most other backgrounds (especially orange) it looks much better.

For those who are interested, I've put two photos on the web that show the difference when playing Quadrant (I'll leave these photos online for a few weeks): one showing the picture on my Panasonic TV set (135 KB), and the other one showing the game running on the same machine, but connected to my old Sanyo Monitor (215 KB).

The main problem with that game is the orange area - since Quadrant is a horizontal scroller, with those stationary lines it just does not look right. As you can see, on the Sanyo Monitor the picture looks quite acceptable.

Conclusion: if your VIC is affected by the vertical line problem, try connecting it to a different TV set or monitor and see if it gets better. But it seems that on a machine affected by this problem these lines will always be visible to some extent.

Regards,

Robert

e5frog · Post by **e5frog** » Tue Mar 18, 2008 6:09 pm

http://hamradio.lakki.iki.fi/new/Magazi ... -tv176.pdf

Page 9

RobertK · Post by **RobertK** » Wed Mar 19, 2008 11:07 am

e5frog wrote:http://hamradio.lakki.iki.fi/new/Magazi ... -tv176.pdf
Page 9

Very interesting! Here's the text from the PDF:

Improving VIC20 Video
[...]
Video Patterning

This shows up as fixed vertical lines on the picture. They are easily hidden with picture detail, but on empty screens are quite apparent. Several attempts at a cure with different layouts & filters (ferrite beads) were tried by the makers, but with not much success.

1/ Add a 220uF directly across the +5V supply (Convenient track connected to pins 40 and 20) next to the video chip slightly reduces it.

2/ The rest of the patterning noise is from strong 1MHz clock pulses for some reason present on the colour Output pin 2. Replacing the simple colour coupling Capacitor for a better high pass C-L-C filter does the rest. There is room in the board for these extra 2 components after removing the odd Ferrite bead link! The L between 10-50uH is best found on test so that the colour delay is not too apparent but the patterning is well down, so start with 10 turns on a ferrite tuning core.

Maybe someone who is a little more talented in soldering than me would like to try this first...

e5frog · Post by **e5frog** » Wed Mar 19, 2008 1:36 pm

As I had my VIC apart I tried the easy first remedy there and added that cap - the lines got less visible.

I'm using a 1084S-II and composite video.

a4000bear · Post by **a4000bear** » Thu Mar 20, 2008 2:57 am

Its caused by the 1MHz clock leaking into the chrominance circuits inside the VIC chip. It becomes visible as the VIC uses composite video - basically the chrominance and luminance are connected together, allowing the spurious signals to interfere with the luminance signal and become visible. It can be reduced a little by better bypassing on the 5V pin on the VIC chip.

A better way will be to convert the VIC to S-video. This will almost completely eliminate it. See the S-video thread elsewhere for details.

e5frog · Post by **e5frog** » Thu Mar 20, 2008 5:06 pm

I'd do the S-video mod right away if I had that type of connector which is on the C64, so I can use either S-video or composite. I'd like to be able to use the RF modulator in case I need to...

Perhaps I'll just swap with one of the C64:s I have... it's worth considering.

eslapion · Post by **eslapion** » Thu Mar 20, 2008 11:33 pm

I can confim the S-Video mod nearly completely eliminates the vertical lines.

Its a really good mod which considerably improves the image quality but the special 8 pin DIN with 262 degrees of the C64 is very difficult to find.

Everywhere I tried buying new 8 pin DIN connectors, they only had the 270 degrees kind available and its not compatible with the 64's video cables.

e5frog · Post by **e5frog** » Sat Mar 29, 2008 3:32 pm

I swapped a/v connectors with a C64, and did the S-video mod - it's really great! Sharp and crystal clear image.

I can still see some very faint lines on blue and red screens, but it's nothing compared to before the mod.

http://sleepingelephant.com/ipw-web/bul ... c&start=29