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JeffsFort

Ghosting issue is Haunting me!

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9 hours ago, cwilkson said:

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

 

I did actually. I had another Rev 16 machine so I tried swapping and there was no change. That was why I had ruled out the TIA. (Issue didn't follow it to the other machine.) That machine id on Ebay now so I don't want to risk another swap. I do have two parts machines coming in, one appears to be fixable. If it is and is decent, then maybe I'll be able to parts swap until I find the bad apple :) Or swap boards... That's not off the table either. They are both Vaders so hopefully Rev 16 and up. Looks like I have some trial and error ahead :)

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10 hours ago, cwilkson said:

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

 

 I did. I had another that works fine so one of the first things I checked was if the TIA was faulting. It made no difference and the issue didn't follow it to the other machine so, there went that theory. I did find a couple of "for parts" Vaders on Ebay and grabbed them. One of them looks potentially fixable so, I may be able to do some more swapping of components in search of the bad apple. Might get lucky.

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On 8/14/2021 at 6:42 PM, cwilkson said:

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?

 

Odd, I answered this a couple of days ago yet, here we are :)

 

Yes, the dead Atari I revived before this one was the donor. Unfortunately I only swapped the TIA, didn't think to do the same with the RIOT or CPU as they didn't strike me as suspect at the time and that was recently sold on Ebay. The only other machine I have here is a Sunnyvale 4 switch "Woodie" that is listed on Ebay right now so, I don't want to risk damage incase it moves.

 

I was lucky enough to find a couple of basement find Vaders that were being sold as a pair for parts. Snagged them both for $15 and even though one looks potentially fixable, they both appear to be in okay shape. I'm thinking get the complete console up and running (Ideally) and use it to swap off parts until the culprit has been identified. Or if it comes back from the dead as well as the other two and I can't get this one to cooperate, swap out the motherboard. Just in principle alone I want to figure out the problem and fix it, even just to learn some more. If the second Atari sells (First one was bought for $25 not working, after a day of work and about $9 in components, it got bid up to $102 so fingers crossed) I may want to consider finding an oscilloscope that I can afford to put my hands on. We'll see :) Thanks for all the suggestions. I'll report in on this thread once I have something to report 😁  For now, it is back up and running and still looking pretty bad for an old guy 🤣

IMG_3330.jpg

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Well just so you are aware... even on the 7800 at least, a UAV will still show ghosting on the 2600 side of things. Much worse on composite, but still ever so slightly through s-video but not nearly to the degree you have shown here. I've have only installed a UAV once on a 2600 and it was actually a vader and it didn't present these issues. But I also did a complete refurb on that vader unit with the refurb kit from console5. So the 2 main electrolytics where changed out along with the green poly cap near the regulator and the small cap near the DC power input. Also a new VR was installed as part of the kit.

 

So basically a lot of stuff was all changed out all at once for my client at their request.

 

 

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The Console5 Refresh and Cap kit was also installed on this machine. When I determined that it was the voltage regulator that was dead and the reason it was being sold for parts, I figured it would be a good idea to be proactive and swap out the components that are more prone to fail. It was around $7 and included the new VR which which was what I needed. At the time I had reasoned that the poly cap "Green Chicklet" is intended to reduce noise coming in from the power supply so it was an early uninformed attempt to address the ghosting.

 

I'm thinking if the two machines coming in both appear to have restorable or at least useable cabinets, and if one of them is in working order with cleaner video, then I may move this motherboard into one of the other cabinets to continue to look for a solution. I've already learned quite a bit I didn't know before cracking open my first restoration so, I'll continue to press for an answer. Why not, right? 😂

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There are enough 2600's around that it's ok to experiment and learn as you go.  Good job!  Keep it up!

 

This is a problem with the motherboard.  Swapping a TIA from a known good system without improvement has proven that.  So the problem is easily fixed...once you find it.  :)

The 5V power seems good according to your measurements.  The boosted delay voltage on pin 10 shouldn't affect it either. It could be a leaky component or it could be some kind of reflection coming out of the RF section or it could be....something?  But it's 100% fixable.

 

Do you have the ability to make a EPROM cartridge?  Or have something like a programmable cartridge (Harmony, etc....I'm not sure what out there these days)?

If you do then I can send you a test .BIN so you have a known video signal for testing visually or with a scope.

 

If you do decide to get an oscilloscope, get a used analog one, with 2 or 4 channels, 50MHz or above, and demonstrated all channels working.  This will be under $100 and could be $50.  You don't need anything fancy for working on these.  And as always, ask for help in this thread.

 

Where are you located?  Some areas are flush with used gear, some not so much.  You may also be near someone with a scope that you could borrow.

 

 

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I actually do own a Harmony Cartridge so I can run a .BIN with no problem. That would really be appreciated. I had done some poking around to see if someone had created some form of "Test Pattern" for color adjusting. The EPROM you recommend I didn't even consider. I may just start building a .BIN "toolbox" folder on mine :)

 

I absolutely will be looking into purchasing an oscilloscope. My initial searches showed an overwhelming number of possibilities with varying prices of really cheap to "Go ahead, sell the car..." Thank you for the recommendation and all your help! It is very appreciated.

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On 8/13/2021 at 5:43 PM, 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' 🤪

Assuming the UAV buffers the Luma signals from the TIA then yea it would help here. 

I am beginning to think that your issue is on the buffer just FYI. 

 

It could also be an impedance issue or something with the kit as it is. Regardless, I would bet that the UAV would fix all your problems here. 

Also might not be a good idea to run Chroma and Luma parallel like that since those signals could induce voltage onto one another. 

Chroma would be a potentially bad source of noise for Luma. It is probably okay if they are individually shielded wires but idk. 

Edited by the_crayon_king

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I believe the UAV buffers the Luma signals from what i've read. My knowledge is limited but, it is expanding as I go. I did verify that that there are no issues with the TIA, RIOT, or the 6507 by swapping them out with another working machine. (Both the "parts" machines I grabbed I was able to get up and running, one of them will end out being a complete system when I'm done as other than needing to replace the 2200uF Capacitor, it is completely checking out.)

 

So, I'm thinking I may look into a UAV mod and keep this basic AV mod for a machine that isn't already showing symptoms. Trial and error...

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Sorry...not a lot of free time...

 

there is a problem on the motherboard.  The only likely way a mod will help is if it completely isolates the TIA pins from the MB.

Gotta find that problem first!

 

I can help with debug over a zoom call. But you need an oscilloscope on hand during the call.  Even a loaner scope will do.

Edited by cwilkson

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That'll take some time. I am in the process of packing up my house to move both myself and my workplace. (The house we are renting is being sold and our office hasn't been used in over a year now... Sigh.) I will look into an oscilloscope and see what I can learn about the specifics to look for and give a yell when all is settled. Things should lighten up after September 14, I hope.

 

Thank you all for your help! I'll put the project down for a while, partly because I need to pack it all up to move 😪

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