Atari 2600 CleanComp Composite Mod - Feedback & Testing

[+-^CrossBow^-]

12 minutes ago, retrosix said:

Those lines definitely not normal. Can you do a video while also turning the Atari's color wheel? Looks like what happens when you put an NTSC game in a PAL console or vice versa, and the chroma timing is out.

As I answered this on the FB group posting where you also stated the same thing...

 

turning the color trimmer just changes the tint I see on the screen and does not change the presence of the jail bars. They are also present on composite but not as pronounced as they are in s-video. 

 

How are you handling the 'stereo' of the TIA? It would normally require you to severe the trace for pin 12 and 13 on the main board since they are tied together. Or, as was done in the past, lifting pins 12 and 13 off the board to isolate them since the connected trace is usually located under the TIA itself or socket if one was installed? 

 

So I'm curious to know how you are separating these from each other on your board in a manner that prevents the pins from still bleeding over to the other without that separation?

 

[cwilkson]

Those bars are from a high-amplitude chroma signal coupling into the luma signal.

 

It should not happen with S-video unless you use unbuffered signals for mixing a composite signal.  It can also happen with many "magic bullet" video mixer ICs.  Bad layout on the board and poor quality cables will compound the problem.

 

Unfortunately the bars *will* happen with composite to some extent...by definition of composite.  And ironically, it will look worse on better monitors with more lines of horizontal resolution.  They have a better ability to produce sharp vertical edges and they are able to reproduce finer gradations of luminosity too.  It's a bad combination.  That's why I tested all of my stuff with the "HR" (High Resolution) version of the Sony PVM monitor.  It was absolutely beautiful and terrible at the same time!  LOL

 

Possible after the fact work around for this thing:  If your monitor has a NTSC comb filter available MAKE SURE IT'S TURNED ON!

[+-^CrossBow^-]

53 minutes ago, cwilkson said:

Those bars are from a high-amplitude chroma signal coupling into the luma signal.

 

It should not happen with S-video unless you use unbuffered signals for mixing a composite signal.  It can also happen with many "magic bullet" video mixer ICs.  Bad layout on the board and poor quality cables will compound the problem.

 

Unfortunately the bars *will* happen with composite to some extent...by definition of composite.  And ironically, it will look worse on better monitors with more lines of horizontal resolution.  They have a better ability to produce sharp vertical edges and they are able to reproduce finer gradations of luminosity too.  It's a bad combination.  That's why I tested all of my stuff with the "HR" (High Resolution) version of the Sony PVM monitor.  It was absolutely beautiful and terrible at the same time!  LOL

 

Possible after the fact work around for this thing:  If your monitor has a NTSC comb filter available MAKE SURE IT'S TURNED ON!

The s-video output is from an old Dell 4:3 aspect computer monitor I use that has many different analog inputs on it. The composite output that I might not have shown here, is when viewed on my small sony PVM I also use on my work bench. The jail bars aren't so much seen through composite as it actually produces what looks to be a moire pattern across the whole screen that is actually visible to the eye.

 

[cwilkson]

Moire pattern on screen is interesting.  Does it change if you move your head?  Which PVM is that?  Overall it looks nice!

 

If you don't see the bars in composite it probably has the comb filter enabled.  Esecially with how bad they are on the other display.  If that was S-video, then the luma signal is filthy with chroma contamination.

 

BTW, you can see a red shift on the left side of the tree trunks and a green shift on the right side in Pitfall above.  It could be caused by a phase shift between the luma and chroma components on the new video board.  But it could also be due to the basic nature of NTSC.  You can't escape those vertical edge color artifacts entirely without specific filtering inside the monitor.  It's in the design of the NTSC chroma signal.  And better monitors will be able to show it better.  Unfortunately.  In general when trying to retro fit these upgrades to old consoles, sometimes better is less desirable.  It's funny.

 

Check Pitfall II to see how sharp the color changes are.  Pitfall II is more pronounced due to the particular color hues chosen for trees vs. background.  IIRC, Pitfall II has a right side shadow that is unavoidable.

 

And check both composite and s-video.  Composite comes with some special problems, but it also hides a mulitude of sins.  S-video will tell you how well the Luma and Chroma signals are matched in time and amplitude.

 

 

 

 

 

[+-^CrossBow^-]

36 minutes ago, cwilkson said:

Moire pattern on screen is interesting.  Does it change if you move your head?  Which PVM is that?  Overall it looks nice!

 

If you don't see the bars in composite it probably has the comb filter enabled.  Esecially with how bad they are on the other display.  If that was S-video, then the luma signal is filthy with chroma contamination.

 

BTW, you can see a red shift on the left side of the tree trunks and a green shift on the right side in Pitfall above.  It could be caused by a phase shift between the luma and chroma components on the new video board.  But it could also be due to the basic nature of NTSC.  You can't escape those vertical edge color artifacts entirely without specific filtering inside the monitor.  It's in the design of the NTSC chroma signal.  And better monitors will be able to show it better.  Unfortunately.  In general when trying to retro fit these upgrades to old consoles, sometimes better is less desirable.  It's funny.

 

Check Pitfall II to see how sharp the color changes are.  Pitfall II is more pronounced due to the particular color hues chosen for trees vs. background.  IIRC, Pitfall II has a right side shadow that is unavoidable.

 

And check both composite and s-video.  Composite comes with some special problems, but it also hides a mulitude of sins.  S-video will tell you how well the Luma and Chroma signals are matched in time and amplitude.

 

 

 

 

 

Not sure which model exactly. It is only like an 8" screen and it can only accept composite and s-video via BNC. I used to use it for both until I got that Dell LCD that has all the analog stuff on it as it just made it easier to use for higher end video output. 

 

The Moire pattern did not change when moving my head it was a static effect on the screen. I don't have the s-video wired up off that board currently, but I can attach some jumper wires to it from a breadboard to get some temp connections up. That way I can pull the chroma to see if I see that bars in the luma signal as well or if it only happens when chroma is introduced. As for the bleeding off the trees, yeah all of the composite outputs I've seen from cheap to UAV, and this board will all have some of that going on. The amount and how bad it what differs between them. The composite from this board isn't that bad and between it and the s-video, I decided to dedicate it for composite on this 2600jr. Otherwise, I would have gone with s-video as I usually do.

 

 

[retrosix]

On 2/22/2023 at 4:07 PM, -^CrossBow^- said:

As I answered this on the FB group posting where you also stated the same thing...

 

turning the color trimmer just changes the tint I see on the screen and does not change the presence of the jail bars. They are also present on composite but not as pronounced as they are in s-video. 

 

How are you handling the 'stereo' of the TIA? It would normally require you to severe the trace for pin 12 and 13 on the main board since they are tied together. Or, as was done in the past, lifting pins 12 and 13 off the board to isolate them since the connected trace is usually located under the TIA itself or socket if one was installed? 

 

So I'm curious to know how you are separating these from each other on your board in a manner that prevents the pins from still bleeding over to the other without that separation?

 

Yes for NTSC you would have to sever the trace or lift pins etc.. I'll explain that in the install vid for those that want to try the stereo version

[retrosix]

So the first version v1.0 is out. https://retrosix.co.uk/Atari-2600-CleanComp-p537997297

 

Lots of improvements and done a full scope of the outputs for those interested (seems lots here are interested in the hardware side).

 

This is through a cheap capture card, and output on actual monitors shows even nicer, but at least this shows the worse case.

 

Composite:

 

 

 

S-Video (brightness +10 to give similar visual as composite as the capture card has different base levels of brightness for them)

 

 

 

Now I have these production boards I have also done some further improvements to come out in the next version. So important notes for this release:

 

1. LUMA0 is still much more delayed than LUMA1/2 now everything is cleaned up (so you will see the black line on back in pitfall). I have also had to over-dampen the luma to compensate the mixing of the LUMA pins together. Plan to fix with a 85ns delay circuit next time

2. Using switch mode power supplies (instead of transformer based) will introduce 2MHz visual noise all over the image. Not sure if this is normal with RF and other mods, but plan to find a way to filter the system/CleanComp next version. So use high quality/original transformer based power supplies for now.

3. Chroma merges into SYNC rise now I don't put additional load on the TIA pins. Doesn't seem to visually effect anything but I will remove the sync tip undershoot next version with faster transistor

 

 

To confirm the signals I have used a PicoScope 4444 (the lowest noise differential scope you can get). Internal noise is 9mV from the scope so thats the lowest measurement we can trust. 

 

Measuring the noise its 14mV so there is a tiny bit of noise to still try and clean up, but overall I'm happy with it.

 

 

S-Video has had very little testing, but hopefully I will get plenty of feedback from this release to then improve that if needed.

 

 

 

 

[cwilkson]

Nice update.

 

There is quite a bit of noise and edge fuzz in the screen captures.  I would like to see photos vs. captures to see how much of that is caused by sampling.

 

Your composite waveforms look surprisingly nice.  Good band filtering where there's color.  Some over/undershoot on the luma stairsteps but it's minimal.  Good job!

 

It's great that you're using a scope to actually *see* what's happening vs. guessing and hacking.  Makes it *much* easier to improve things.

Keep working on the timing between signals.  Those spikes are pretty severe and might be visible on a good monitor.  Especially if they happen at a bad time.  Need to hammer them flat! 

 

Be sure to check the waveforms with color active at both edges of the blank pulse.  That's one of those bad times.

 

Looking forward to the deep dive for S-video.

 

 

 

 

[retrosix]

Yes the unsharp luma is caused by the TIA delaying the Luma 0 and the requirement to then over dampen with a 1nf cap on luma stage. Need a huge 85ns delay circuit for Luma 1 and 2 for next version then can re sharpen luma. 

 

Chrome causing undershoot on sync fixing by faster response transistors on SYNC input stage. 

 

Hopefully those 2 things remove all remaining wave shape issues. 

 

Final one would be supporting low quality SMPS and seeing if we can clean any more of that 14mV noise. It's not visible at all on any monitor or PVM I have tried only capture card but super hard to photo the monitors without it adding the usual effects you see when photographing them. 

 

Check video out here https://www.tiktok.com/@retrosix/video/7210065739225615622?is_from_webapp=1&sender_device=mobile&sender_web_id=7207524830441883141

 

Photo attached 

 

Pretty sure the noise on captures is the capture card but we will see if others see any noise. 

[cwilkson]

10 hours ago, retrosix said:

 

Check video out here https://www.tiktok.com/@retrosix/video/7210065739225615622?is_from_webapp=1&sender_device=mobile&sender_web_id=7207524830441883141

 

Real quick cinematography advice.  Turn your phone 90 degrees!!!  And tell all your friends to do it too!

To take advantage of basic human vision wetware.  And every computer monitor everywhere.

 

You'll have a bigger viewable image without wasted pixels at the top and bottom and you won't need to pan and scan.

You can then use a cheap tripod to avoid shaky cam effects.  Even propping the phone against a stack of books will work. I said cheap!

[retrosix]

32 minutes ago, cwilkson said:

Real quick cinematography advice.  Turn your phone 90 degrees!!!  And tell all your friends to do it too!

To take advantage of basic human vision wetware.  And every computer monitor everywhere.

 

You'll have a bigger viewable image without wasted pixels at the top and bottom and you won't need to pan and scan.

You can then use a cheap tripod to avoid shaky cam effects.  Even propping the phone against a stack of books will work. I said cheap!

TikTok is portrait only I'm afraid 

[cwilkson]

Why are you using a SMPS?  I don't see a need and it will only cause you extra grief as you've already pointed out.

 

But maybe there's something special in your circuit that requires a weird voltage?

 

For transistors...are you using BJT or FETs?  What type?  BJTs are probably faster at the cheap end, but storage delay will kill you if you don't compensate for it correctly.

              

[cwilkson]

9 minutes ago, retrosix said:

TikTok is portrait only I'm afraid 

What?  Really?  Still?  I thought they supported horizontal video for a year or two.

I admit I'm not into TikTok, but I could swear they support it.

 

Damn.

[FireStar]

Nice to see this is finally out, although I may wind up waiting on v2 since there's already known minor issues. My atari's been without Svideo for 40 years or so so whats another 6 months?

[retrosix]

On 3/14/2023 at 6:12 PM, cwilkson said:

Why are you using a SMPS?  I don't see a need and it will only cause you extra grief as you've already pointed out.

 

But maybe there's something special in your circuit that requires a weird voltage?

 

For transistors...are you using BJT or FETs?  What type?  BJTs are probably faster at the cheap end, but storage delay will kill you if you don't compensate for it correctly.

              

I'm not using transistors like other composite mods, I reconstruct the entire signal. I'm using FETs just for triggering at the start and will use a lower voltage trigger to improve timing. 

 

I'm not using SMPS I'm showing that many (in fact all) third party and common ones sold on market will always be this so it's good to support them. 

[braincell1973]

The Svideo doesn't appear much better than composite and there's an issue with sound 

Edited April 11, 2023 by braincell1973

[+x=usr(1536)]

For those of us without 80 minutes to invest in watching the video, could we have a fuller synopsis, please?

[+Stephen]

4 hours ago, x=usr(1536) said:

For those of us without 80 minutes to invest in watching the video, could we have a fuller synopsis, please?

Or perhaps a 20 second synopsis, rather than an 80-minute ad-generating over talkative, look-at-me, click like and subscribe, I like the sound of my own voice, my farts smell like cotton candy cash grab?

[braincell1973]

Yea, you must be a "special" type of person who clearly didn't even look.......

 

If you had you would know there's no monetisation, no asking for subs or clicking like........

 

And certainly no ad revenue at all.......

 

****-tard above not withstanding the cleancomp doesn't generate the best picture on svideo mode as its not much better the composite.

 

The amplifier that buffers the video signal also seems to have a subtracting effect on the sound causing the ufo sound to disappear in space invaders amongst other sound artifacts........

 

[EricG76]

I installed the CleanComp in my light sixer last weekend.  It replaced a comp. mod I got here in the US on ebay.  The previous comp mod, although a big improvement over original RF had really bad ghosting to right of objects that made certain things hard to decipher.  Also color was fairly dark and Harmony Encore menu was hard to read.  For CleanComp, on the plus side, the ghosting is fixed completely, colors are brighter, and Harmony menus are now easy to read (thanks RetroSix!).  However, I am seeing a bit of jailbar effect but not too bad.  More importantly, the sound as mentioned above is messed up now in certain games.  Space Invaders is missing the space ship sound.  On Pitfall!, the Tarzan rope swinging has a garbled/staticky sound to it now.  For homebrew Vector Vaders the cool sound of cannon blowing up is clipped.  These are a few examples I have come across so far.  I understand this is v1.0 so I didn't expect perfection, hopefully next version will have the audio issues fixed.  

 

RetroSix, I added my setup in my signature line in case that info helps your troubleshooting.

Edited April 12, 2023 by EricG76
additional comment

[braincell1973]

Just run your sound line from the tia pin directly and not the cleancomp , that should sort sound

[+x=usr(1536)]

9 hours ago, braincell1973 said:

Yea, you must be a "special" type of person who clearly didn't even look.......

Yes, because expecting people to sit through an 80-minute video when two minutes of explanation could have avoided all of this makes a great deal of sense.

9 hours ago, braincell1973 said:

If you had you would know there's no monetisation, no asking for subs or clicking like........

 

And certainly no ad revenue at all.......

Clearly, hyperbole and sarcasm are lost on you.

9 hours ago, braincell1973 said:

****-tard above not withstanding the cleancomp doesn't generate the best picture on svideo mode as its not much better the composite.

 

The amplifier that buffers the video signal also seems to have a subtracting effect on the sound causing the ufo sound to disappear in space invaders amongst other sound artifacts........

Excellent use of your third-ever post on the forum, I must say.  Been a while since we've had one of these crop up; I, for one, look forward to the show.

[+x=usr(1536)]

1 hour ago, EricG76 said:

I installed the CleanComp in my light sixer last weekend.  It replaced a comp. mod I got here in the US on ebay.  The previous comp mod, although a big improvement over original RF had really bad ghosting to right of objects that made certain things hard to decipher.  Also color was fairly dark and Harmony Encore menu was hard to read. 

This is on an NTSC machine, correct?

1 hour ago, EricG76 said:

For CleanComp, on the plus side, the ghosting is fixed completely, colors are brighter, and Harmony menus are now easy to read (thanks RetroSix!).  However, I am seeing a bit of jailbar effect but not too bad. 

This jibes with my experience in an NTSC short-rainbow Jr.

1 hour ago, EricG76 said:

More importantly, the sound as mentioned above is messed up now in certain games.  Space Invaders is missing the space ship sound.  On Pitfall!, the Tarzan rope swinging has a garbled/staticky sound to it now.  For homebrew Vector Vaders the cool sound of cannon blowing up is clipped.  These are a few examples I have come across so far.

Something similar happened in the Jr. that I was using.  Audio from its TIA is now dead; it only outputs static.

 

I can't definitively place the blame for the TIA audio problem at the feet of the CleanComp as the Junior in question had had a hard life before I got it.  However, the timing is certainly coincidental, and the TIA had not exhibited audio issues until the CleanComp had been in place for a few days.

 

To reiterate: I'm not blaming the CleanComp, just detailing the timeline of events on my end.

1 hour ago, EricG76 said:

I understand this is v1.0 so I didn't expect perfection, hopefully next version will have the audio issues fixed.  

Mine was a preproduction unit.

[braincell1973]

X=usr....... Clearly you didn't read and understand what I had written, ****-tard ( notice the lack of plural ) referred to the previous post and not yours, however, As you clearly are unable to scan through a video please feel free to apply said ****-tard status to yourself too.

 

 

 

What's more rediculous ? Expecting you to employ a fast forward to the end of a video or expecting me to re-edit the video into a small enough segment that ****-tards can digest ?

 

And yes, It is a shame that a person can make 3 posts and have to defend themselves when simply trying to help........ 

 

[cwilkson]

What is the revision status of the NTSC CleanComp?  (the website says v1.0?)

I'd like to buy one to compare/review, but it clearly has some pretty serious issues remaining.

 

If the next revision with fixes for these issues is almost ready, then I'll wait.

Otherwise I'll get the current revision and live with (or fix) any problems that exist.