Ghosting issue is Haunting me!

[JeffsFort]

Hi all! This is my first post, just joined and happy to have found your community.

 

Long story short, I love the Atari 2600 and finally decided that I wanted to find a broken unit and fix it to use at home. As kids we burned out three consoles and ended out tossing them  Both were most likely fixable too. So I have now purchased three consoles. Two 4 switch Woodies (One of those an early Sunnyvale release) and a Vader. All three non-working for various reasons The two Woodies are looking and running great now with a little attention and a couple of replacement components. My problem child is the Vader.

 

Before doing anything once I finally got it to fire up (Recapped, re-flowed a couple soldier connections, and replaced the power jack), I noticed some ghosting. I did swap its TIA chip with one of the other machines and saw no change. I did decide after finding nothing online that seemed like the same issue, to attempt the AV Composite Mod hoping that eliminating the RF signal would be the fix. Unfortunately, still no change. Any suggestions would be greatly appreciated as this is the machine I'd love to make my daily driver. I'll attach a couple of pics taken after the AV mod on the 13" CRT that is my dedicated Atari monitor. I'll add one of the console itself. It came out looking incredible which is why I really want it working well. Thanks!

[cwilkson]

Which video mod did you do?

[+-^CrossBow^-]

39 minutes ago, cwilkson said:

Which video mod did you do?

Not sure it will matter that much, as I've seen similar ghosting from the UAV on the 2600 side of things through composite on both 2600 and 7800 systems. Only way to eliminate most of that is using the s-video output from a UAV or going with the RGB upgrade.

 

[the_crayon_king]

@-^CrossBow^- Isn't that Chroma shift ? I am not sure how to fix it but the idea is that the chroma is out of time with Luma. 

Some sort of analog delay may fix that. 

[+-^CrossBow^-]

Perhaps, but that discussion was only in regards to the 7800 and the UAV. It looks different than chroma shifting on the 7800. 

[JeffsFort]

9 hours ago, cwilkson said:

Which video mod did you do?

It was the Vintage Gaming mod. The issue existed before doing the mod though. I was hoping it was an RF issue that the Mod would eliminate. So much for THAT theory

[cwilkson]

A good mod should be able to clean up a chroma shift.  But this looks like more than just a chroma shift.  Some ghosting and ringing and shifting in both directions.  Plus sharp edges from the blank signal and they're not well controlled.

 

16 hours ago, JeffsFort said:

It was the Vintage Gaming mod. The issue existed before doing the mod though. I was hoping it was an RF issue that the Mod would eliminate. So much for THAT theory

I'm not familiar with that one.  I'll what I can learn about it.

 

Can you post a picture of the unmodded RF output?  Also post with the mod, but without the chroma connected.

[JeffsFort]

Unfortunately, I didn’t record the video pre-mod. The image was the same with the addition of a little RF noise.

 

As for the mod, it was purchased at vintagegamingandmore.com. I bought two to try in two different machines. This one and another Rev. 16 board. Both upgrades seemed to go well with the exception of this one’s pre-existing condition. 

 

as for posting without chroma connected, I need to do some homework. I’m a noob when it comes to these upgrades or restorations in general. I’ve been excited to get all three non-working machines that I have obtained up and running again but have much more to learn still. Thanks for looking it over. Comforting to have mentors, glad I found you guys

[+-^CrossBow^-]

4 hours ago, cwilkson said:

A good mod should be able to clean up a chroma shift.  But this looks like more than just a chroma shift.  Some ghosting and ringing and shifting in both directions.  Plus sharp edges from the blank signal and they're not well controlled.

 

I'm not familiar with that one.  I'll what I can learn about it.

 

Can you post a picture of the unmodded RF output?  Also post with the mod, but without the chroma connected.

Not sure which kit he has exactly either, but most of the simple composite kits just have you run a wire from the composite input going into the RF section and amp that out. The UAV does use separate LUM and chroma inputs on it, but that isn't what he installed so I'm not sure he can separate that out in this case.

 

Yeap just took a look. The kits are the simple transistor kits so they aren't using the separate inputs and chroma from the TIA as the UAV would require.

 

[cwilkson]

1 hour ago, -^CrossBow^- said:

Yeap just took a look. The kits are the simple transistor kits so they aren't using the separate inputs and chroma from the TIA as the UAV would require.

Ok, so it's a working mod.  But not a good one.  Thanks for doing the leg work!

 

3 hours ago, JeffsFort said:

as for posting without chroma connected, I need to do some homework. I’m a noob when it comes to these upgrades or restorations in general. I’ve been excited to get all three non-working machines that I have obtained up and running again but have much more to learn still. Thanks for looking it over. Comforting to have mentors, glad I found you guys

@JeffsFort, that's a really nice looking Vader 2600 BTW!

 

How good are you with a soldering iron?

On the problem 2600, is your TIA chip socketed?  Or is it soldered directly to the board?

 

Nevermind.  I reread your post.  It's obviously socketed if you're swapping them around.

And it sounds like you're ok with soldering.

 

I can help you separate the chroma.  What is the board revision?

[JeffsFort]

It's a Rev. 16.

 

It came out much better looking than I expected it to. My original intent was to keep one of the Woodies and re-home the Vader but even with this issue, I couldn't do it  I also like the LED placement on the face instead of the control insert better. As a kid, I remember a few times accidentally leaving our system powered and turned on for days if we didn't have time to play. That mod calms my inner panicked child and I think makes the Vader look pretty cool in the process. LOL!

[JeffsFort]

So you can take a look at it. (Note: When removing the RF Modulator, I damaged a topside trace to the nearby capacitor. The red wire routed to the backside is simply bypassing that trace.)

 

[cwilkson]

Ok.  There are a couple of easy ways to separate the chroma on the motherboard.

 

The most effective solder free way is to lift pin 9 of the TIA out of the socket so that just hangs in the air.  That will completely disable [intentional] color.

First, pull the chip from the socket.  Then gently bend the LARGE PART of the pin up just enough that it will miss the socket.  Then reinstall the IC.

 

If you're squeamish about bending the IC pins, (I don't blame you!) then you can remove R228 from the board.  You actually only need to lift one end out of the board.  R228 is the 1K resistor, 2nd from the right end of the TIA in your picture.  It's just to the left of that blue colored diode.  With that resistor out of the circuit you should also lose [intentional] color.

 

With the TIA's color output disconnected from the video circuit on the MB, you should just see a grayscale image on the monitor.

 

Note:

With this motherboard revision, their is a resistor to enhance color saturation.  It will cause unintended color lines on the left and right of the screen.  That's what's causing the blue line on the left of your Pitfall screen.

Without the TIA's color burst output, hopefully it will just go away.  But it may linger as a different gray level line.  You can ignore this for now. 

 

 

[JeffsFort]

Yikes...

 

Yeah, I'll lift R228. Reversible and not intentionally damaging a good TIA. 

 

I'm hoping there is a little more to that fix as it doesn't seem to be completing the job

[cwilkson]

 

That's not a fix.  That's a test.  To see if those ripples are caused by luma or chroma weirdness.

[JeffsFort]

Oh, hehehe. Gotcha.

 

Lifted R228, will test again with Pitfall where the pics I showed used that game and we know what it's issues look like:

 

 

[JeffsFort]

One thing I just noticed before turning it off, if you flip the switch to B&W, the ghosting does lessen. That's probably expected but seemed worth mentioning

[cwilkson]

Ok very nice.

Hard to tell with 100% certainty from the photos, but it looks like some ghosting is present in the luma.  (looking at the ladder and especially the brick wall.)

Is that real?  Or a photo artifact?

 

Only thing I could imagine would be a weak or dirty +5V supply.  Do you by chance have an oscilloscope?

 

 

[JeffsFort]

Unfortunately, I don't.

 

That ghosting is real. I wish I had a better way on hand to capture the video... 

 

I can say that this machine is running on a brand new power supply and had had a new voltage regulator installed that was putting out a solid 5.0. I have used an OEM power supply with this machine as well and there was no change in video. 

Edited August 13, 2021 by JeffsFort

[cwilkson]

Yeah, a lot of people don't have a 'scope.  That's fine.  We can try it with a multimeter.  Do you have one?

 

If so, measure the DC volts from pin 20 (+5V) to pin 1 (GND) on the TIA.  It should read 5.0V or very close.

Then measure the AC volts at the same points.  It should read 0.0V.  The closer the better.

 

Report back.

[cwilkson]

Crazy idea....try a different monitor!!

[JeffsFort]

DC - GND to pin 20 = 4.98V

AC - GND to pin 20 = 0.0V 

 

I do have an older flat screen Emerson I can connect to. It isn't the best quality so, the image seems blurred but, does still show the shadowing albeit not as clearly. (My roommate now thinks I'm nuts. Wandering the house with my Atari and a bunch of wires, talking to myself. ?)

[JeffsFort]

I really want to determine the trouble with this console but, if unable; do you think a proper UAV mod in place of the basic AV mod would have a chance of addressing this issue? It's not out of the question to upgrade the upgrade, just sayin' ?

[+-^CrossBow^-]

16 hours ago, JeffsFort said:

I really want to determine the trouble with this console but, if unable; do you think a proper UAV mod in place of the basic AV mod would have a chance of addressing this issue? It's not out of the question to upgrade the upgrade, just sayin' ?

I'm not sure in this case. The problem here is that you seem to have ghosting on the LUMA signals and not just the Chroma. The UAV takes in all of the individual signals from the TIA and combines them through a replacement video encoder to provide you with the new composite and s-video outputs. But like anything else, it is dependent on the initial input signals in the first place. So if the bleeding is coming from the TIA itself, then it might not make much difference.

 

 

[cwilkson]

8 hours ago, -^CrossBow^- said:

I'm not sure in this case. The problem here is that you seem to have ghosting on the LUMA signals and not just the Chroma. The UAV takes in all of the individual signals from the TIA and combines them through a replacement video encoder to provide you with the new composite and s-video outputs. But like anything else, it is dependent on the initial input signals in the first place. So if the bleeding is coming from the TIA itself, then it might not make much difference.

The ghost is in the machine!

 

I agree with -^CrossBow^-.  Since you have some luma issues I don't think another upgrade will make a lot of difference.  The CyberTech might be able to do it but I haven't made those in years and it's still a crap shoot without knowing the root cause of the ghosting.

 

If you had an oscilloscope you could chase the individual signals around the MB and find the problem.  But without that, a chip swap is the only thing I can think of to try.

Did you say you already tried swapping the TIA from the working console into this one?