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Justin Payne

Video garbage on just obtained 1200xl

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Just got a 1200xl that needed a bit of love but I see I have a bit of a video issue. The power plug did have a bit of corrosion on it. Cleaned that right up so maybe the cart slot has the same but when I tried a BASIC cart, image seemed clean but Missile Command and Barnyard Blaster does show the issue. I'm connect to my monitor via the monitor output (din).

Of course, the first one thinks are caps but before I go replacing them I thought I would get people's two cents.

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Edited by Justin Payne

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Of the two 1200's I've seen, video output varied from one extreme to the other. No idea why. A UAV-D fixed the one. 😃  Have you used that same video cable and monitor on another A8?

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If it was the caps then surely the Basic screen would have been the same as Missile Command..

 

Have you tried reseating and socketed IC's?

 

And a thorough RAM test might be worth doing..If the RAM is bad then depending on where the program sets the screen location it could show that mess and another program using a different location would look clean iirc.

Edited by Mclaneinc

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8 hours ago, Justin Payne said:

20210202_215850.jpg

 

It kinda looks like your 1200XL is in The Matrix....  😀

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41 minutes ago, StickJock said:

It kinda looks like your 1200XL is in The Matrix....  😀

😆.....Wait 🤨 Does that mean I too am in The Matrix? If alcohol cleaned up my keyboard issues. Which pill cleans up my video issue? 🤔

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2 hours ago, DrVenkman said:

That looks like a bad/unshielded cable to me. Nothing to do with caps. 

It's the same cable and monitor I use for my standard 800 and no video issues with that.

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4 minutes ago, Justin Payne said:

😆.....Wait 🤨 Does that mean I too am in The Matrix? If alcohol cleaned up my keyboard issues. Which pill cleans up my video issue? 🤔

I suppose that would depend on if you have NTSC pills or PAL pills, and how your color pot is adjusted!

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1 hour ago, Mclaneinc said:

If it was the caps then surely the Basic screen would have been the same as Missile Command..

 

Have you tried reseating and socketed IC's?

 

And a thorough RAM test might be worth doing..If the RAM is bad then depending on where the program sets the screen location it could show that mess and another program using a different location would look clean iirc.

I agree. That's what I thought was strange. With Barnyard Blaster (BB), the interference is about the same when it transitions between screens. For example, the moment where the screen goes black is when it's very pronounced. Since Missile Command uses a black background, maybe black is a necessary component BUT as you can see when BB has a title screen up, the interference is there on the black areas but it much less pronounced. 

No, I haven't tried that yet. I haven't removed the shielding yet but that's always a good action to do.

Yes, did a RAM test. All tests returned with perfect results. 

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2 minutes ago, StickJock said:

I suppose that would depend on if you have NTSC pills or PAL pills, and how your color pot is adjusted!

Pot, eh? I'm going to be so lit after this that I might not ever notice this video issue. 😄

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1 minute ago, Justin Payne said:

Pot, eh? I'm going to be so lit after this that I might not ever notice this video issue. 😄

Just make sure you don't let the magic smoke out of your 1200XL!

 

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15 minutes ago, StickJock said:

Just make sure you don't let the magic smoke out of your 1200XL!

 

Good suggestion.  When I'm done fixing this issue I'll make sure to plug any holes where it can get out. Of course, I suspect that will severely limit my ability to use the system but at least the smoke is contained. We all have to make sacrifices for the greater good. 🤪

Edited by Justin Payne

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24 minutes ago, Justin Payne said:

It's the same cable and monitor I use for my standard 800 and no video issues with that.

That may be the case but 1200XL video is notoriously the worst of the A8 line and those vertical lines sure look like typical DRAM refresh lines, worsened by interference or RF somewhere in the signal path. 

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8 minutes ago, DrVenkman said:

That may be the case but 1200XL video is notoriously the worst of the A8 line and those vertical lines sure look like typical DRAM refresh lines, worsened by interference or RF somewhere in the signal path. 

So, if the internal RAM diagnostic passed, what are other suggestions? I do see that "DRAM refresh issues" discussed here (

) but this seems way more serious.
Here is what I'm thinking. If everything is socketed, I could pull all of the chips and make sure all of the contacts are clean. I could also spray some contact cleaner into the monitor plug and see if I can get a small wire brush in there to clean off the surface of anything that could be causing interference. The cartridge port was a bit finicky unless I cleaned it up a bit and since the power port also had a contact issue, I suspect this port would be no different. but 

Edited by Justin Payne
Wanted to add a link to another thread that discussed the DRAM refresh issue

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What does it look like with no cart? Boot to DOS?

 

Which video connectors are you using? Composite? S-Video?

 

Bob

 

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3 minutes ago, bob1200xl said:

What does it look like with no cart? Boot to DOS?

 

Which video connectors are you using? Composite? S-Video?

 

Bob

 

It looks fine so that, originally, made me think the cart port was dirty.
I'm using the "television monitor jack" and that is plugged into the composite connector on the back of my LCD TV.

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39 minutes ago, Justin Payne said:

I'm using the "television monitor jack" and that is plugged into the composite connector on the back of my LCD TV.

The 5-pin video DIN connector, right?

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1 minute ago, DrVenkman said:

The 5-pin video DIN connector, right?

Correct. 👍

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Just now, Justin Payne said:

Correct. 👍

The 1200XL has terrible stock composite video. It has a saturation boost in the circuit that is over-driving your TV’s ability to show a clean signal. If your video cable has separate chroma and luma connectors, try putting the Luma connector into your TV’s jack. You will have a B&W image, but you can see if the problems are limited to the composite signal at least. 

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Take especially good care of cleaning and reseating the GTIA chip and its 4050 helper. That's where the video signal is generated.

 

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9 minutes ago, DrVenkman said:

The 1200XL has terrible stock composite video. It has a saturation boost in the circuit that is over-driving your TV’s ability to show a clean signal. If your video cable has separate chroma and luma connectors, try putting the Luma connector into your TV’s jack. You will have a B&W image, but you can see if the problems are limited to the composite signal at least. 

I don't think it's the cable. Sorry for the moire pattern but the image is clean.

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Edited by Justin Payne
Spell check "fixed" moire.

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Your monitor and 1200XL don't like each other...  but, that isn't causing the 'birdies' on your first screen. That's broke. Only with a cartridge? 

 

The 1200XL has bad cartridge karma, as well. Late versions of Congo Bongo and other carts fail spectacularly. You need to beef up ground paths and such to fix them. The system clock is asymmetrical, causing decoding glitches. On and on...

 

Best path is to swap motherboards with one from BOB1200XL.

 

Bob

 

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3 hours ago, bob1200xl said:

Your monitor and 1200XL don't like each other...  but, that isn't causing the 'birdies' on your first screen. That's broke. Only with a cartridge? 

 

The 1200XL has bad cartridge karma, as well. Late versions of Congo Bongo and other carts fail spectacularly. You need to beef up ground paths and such to fix them. The system clock is asymmetrical, causing decoding glitches. On and on...

 

Best path is to swap motherboards with one from BOB1200XL.

 

Bob

 

Well, the good news it's not my only system so if one cart fails, I'll just play it on another so although the BOB1200XL is a great option, it's probably not necessary for more needs.That grounding issue is interesting and so is the asymmetrical clock. Do we have aa definitive, "Everything wrong with the 1200xl" list as well as a "How to make the 1200xl better"? 

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Opened her up and she looks good inside. Pushed down on all of the chips but all were pretty well seated. Gently cleaned the cart port with a bit of 91% Isopropyl alcohol and a small wire brush.
BTW: Once and a while when I turn the 1200xl, the screen is just green. Turning it back off and one resolves the issue. It doesn't happen often but does happen from time to time. I saw some posts where people had the issue all of the time. Probably going to use a chip puller and just pull em out a little and reseat them again to scrape off any possible corrosion. 

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