Minimizing jailbar/vertical lines on 2600?

[rednakes1]

Would the green "chiclet" capacitor next to the 7805 voltage regulator have anything to do with it? Normally it would need to be replaced if the image starts showing snowy static after a while of playing.

 

For our vertical banding issue it seems like interference between parts. Maybe the power source at the RF connector (pin 3) needs to be taken from a spot closer to the 5V source? In my modded system I was using that same pin.

[AtariLeaf]

Honestly I don't know, this techy stuff is way above my head

[rednakes1]

Well, my reply was directed at the Atari experts on this forum

 

I've noticed this vertical banding / jailbar issue in other threads for other hardware. I'll try to find examples from other threads later. Seems to be a common issue but is fixable.

[Keatah]

No these are lines up and down the entire screen, similar to the jailbar lines on a toploader. This is not my picture just an example of what I'm talking about

 

 

 

 

It's interesting to note the whitish lines are aligned with the ladders. The black lines, can't really do anything there, the system is doing internal processing. Read Racing The Beam.

 

Without putting the system on my bench, I'd be inclined to guess noisy ICs and 40 year capacitors losing ability to filter and buffer. Along with dirty connections and noisy ground. It all adds up to what you're seeing.

Edited November 22, 2016 by Keatah

[Keatah]

duplicate

Edited November 22, 2016 by Keatah

[AtariLeaf]

Well I've tried a couple of vaders, same issue and the light sears sixer I thought was ok, does have the lines show up if i fiddle with brightness and contrast. That brings me up to seven known systems with these lines, tested on two different commodore 1702 monitors via a common vcr as well as a direct rf connection to another crt tv using different power supplies and different house plugs. The systems all run otherwise normally. I'm seriously doubting the RIOT chip now, there's no way all these chips are going like this.

 

It is an annoyance though. I can't wrap my head around the bad luck I must be having if only I and one other person on atariage have had this issue and I have at least seven systems displaying this behavior.

Edited November 22, 2016 by AtariLeaf

[zylon]

Since both of you are from the same region, yet different than ours, I'd have to wonder if your local power system might be the culprit. I've seen houses in the north that had much higher voltages than expected.

[Keatah]

Couple volts AC difference should be masked by the regulator.

[zylon]

Couple volts AC difference should be masked by the regulator.

 

How about differences of +30VAC or so? One house in particular had over 150VAC at the receptacles. Power bricks or wallwarts used to melt if left plugged too long there.

[zylon]

 

How about differences of +30VAC or so? One house in particular had over 150VAC at the receptacles. Power bricks or wallwarts used to melt if left plugged too long there.

 

Another example is I have a Genesis 2 system with a modern replacement power supply. If I use it here in Georgia, it works fine. If I take that same unit and power supply to my home in Pennsylvania, I get terrible interference in both audio and video.

[rednakes1]

Was playing Atari just now. Couldn't stand those lines on the screen.. ugh. Here's an example.

[rednakes1]

Another example is I have a Genesis 2 system with a modern replacement power supply. If I use it here in Georgia, it works fine. If I take that same unit and power supply to my home in Pennsylvania, I get terrible interference in both audio and video.

Maybe I'll try this upstairs then. I have mine plugged in the basement on a CRT, but it did happen on an LCD monitor down here as well.

[zylon]

Maybe I'll try this upstairs then. I have mine plugged in the basement on a CRT, but it did happen on an LCD monitor down here as well.

 

In the case of that Sega, you would actually hear broadcasts through the TV in between rounds in Mortal Kombat 3.

[Keatah]

I tried a 7800 and a Coco 2 with no vertical lines but it is on various atari systems. i tried to take a picture but its hard to tell but if you look closely, especially at the bottom of the screen, you can see the bluish thin vertical lines running through the whole screen.

 

Looks about the same as the first photo dated 2009. Same spacing, same pattern. Looks like logic noise not getting filtered out. Or being coupled where it shouldn't.

[Keatah]

How about differences of +30VAC or so? One house in particular had over 150VAC at the receptacles. Power bricks or wallwarts used to melt if left plugged too long there.

 

Ouch that's getting up there.

 

[AtariLeaf]

I use a surge suppressor but If it is the power (and it's something I've wondered may be the culprit) would this minor difference cause permanent damage or is the difference just manifesting in these lines?

[AtariLeaf]

 

Looks about the same as the first photo dated 2009. Same spacing, same pattern. Looks like logic noise not getting filtered out. Or being coupled where it shouldn't.

 

Theoretically, how would one filter out this noise? Capacitor out of spec or dying?

[zylon]

 

Ouch that's getting up there.

 

 

That one was in Scranton, PA. Since it was an apartment, I advised the person to move. They did and magically had no more power issues at their next apartment.

[rednakes1]

I do remember when I was doing one of the composite mods (the 2 resistor + 1 transistor), that when I removed capacitor C215 (150 pF), the vertical lines would look way worse and the picture would look grainier. If you look at the schematic, this is the last capacitor that feeds into the Video Out going to the RF modulator. So in this case the cap does have a big effect.

 

I tried employing the same technique in my current mod (which looks better than the former mod, but does not improve on the vertical lines) but had no luck with different sizes of caps.

Edited November 22, 2016 by rednakes1

[rednakes1]

I tried the Atari just now on a big screen LCD on my main floor. The video quality is horrendous LOL and the vertical lines are still there; no improvement. I don't want to bother trying on the top floor as that TV is mounted to a wall.

[rednakes1]

In the case of that Sega, you would actually hear broadcasts through the TV in between rounds in Mortal Kombat 3.

I have other things plugged into that same CRT TV via composite input - an Atari Flashback 2, a PS2 and also a modded Colecovision. None of them have this problem with jailbars but it could just be that they have better noise suppression circuitry than the 2600.

[Keatah]

I use a surge suppressor but If it is the power (and it's something I've wondered may be the culprit) would this minor difference cause permanent damage or is the difference just manifesting in these lines?

Theoretically, how would one filter out this noise? Capacitor out of spec or dying?

 

When playing with VCS, you're playing in an analog video world. There's many entrance points for noise and interference, even the interplay of frequencies and their harmonics going back and forth between components in close proximity to each other is a potential source. That's a fancy way of saying one part can interfere with another part just because they're physically close by.

 

Got a leaky transistor or capacitor out of spec, or getting weak, or developing resistance? Sure, that can cause it. And there are a lot of discrete parts for a system as simple as the VCS. Just a sign of the times, neither good nor bad.

 

A surge suppressor could help, provided dirty AC is the source. We do not know whether it is or isn't. A slight steady overvoltage isn't going trip it or get filtered out. For bad power, an active conditioner with battery backup is about the best a consumer can get. It takes incoming AC converts it to DC to charge a battery and power an oscillator. The AC waveform is built back up and then sent to you. Be sure it's a real AC sine wave coming out. There are cheap-ass ones that modulate a square wave, which is just more noise, and very harmful to transformers and parts immediately connected to them.

 

Anyhow. I'd attack this problem by looking at ripple and noise and harmonics at various points in the circuit. Deconstruct the video signal and determine the frequency of the jailbars. Compare it directly against the video signal. I can pretty much guarantee you there will be a correlation between the frequency of those lines and an data/address line.

 

I've solved these sorts of problems a number of times. Each having a different solution depending on the exact part that failed. Could even be weak decoupling between 2 IC's power rails..

 

Two choices:

 

1- keep experimenting and swapping parts till it goes away.

2- put it in the shop and trace the problem to its source.

 

---

[Keatah]

Once I clear out some backlog and wrap up a few projects I'd like to see your VCS. Perhaps we could arrange something when the holidays end. I've got resources to narrow this down. And the VCS is a rather simple circuit overall. Clever, but simple.

[rednakes1]

Once I clear out some backlog and wrap up a few projects I'd like to see your VCS. Perhaps we could arrange something when the holidays end. I've got resources to narrow this down. And the VCS is a rather simple circuit overall. Clever, but simple.

I would have liked to ship you mine, but I modded it, and with a dozen wires and a perfboard it's kind of delicate. I have another one as well (RF) but it needs minor repair. I'll see if I can get it fixed in time... it has vertical banding but not so obvious due to the bad static.

 

I'm wondering if it will be a universal issue, same spot in all these problem four-switches.

[AtariLeaf]

I was going through facebook and someone posted some pics on the atariage page. I noticed what looked like the same lines in this pic of combat (hope the person who posted this doesn't mind). It's hard to tell since it's a photo of a screen but those faint vertical lines all across the screen are exactly what I'm talking about.