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spinnaker15136

Not getting crisp white characters on TV from Atari 800

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Posted (edited)

Most of the images and videos I have seen of screens from an Atari 800 show nice crisp white characters. At least one of those videos was showing an old CRT type monitor.

 

I am using my LCD TV. I am getting sort of a magenta tint to the characters and the blue background isn't exactly blue. I played with the settings on my TV and improved it a bit but the magenta tint persists. Is this just normal and I am not remembering it? Is it because I am using an LCD? Or is there something wrong.

 

Donkey Kong seems kind of washed out as well as Ghost Hunter, At least from the way I remember it. I can post those images later if requested.

 

 

 

post-68113-0-26704600-1556417813_thumb.png

Edited by spinnaker15136

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Couple things -

 

1. How are you connected? RF through channel 2/3 on your TV? Composite?S-video?

 

2. Yes, modern LCDs interpret the NTSC color gamut a bit differently than CRTs do. You can adjust the color potentiometer inside your Atari to tweak the color balance to your liking, but LCDs will always look a little bit different than CRTs, especially through RF or Composite. S-Video (Chroma/Luma) will give better and more accurate color but again CRTs and LCD are just different.

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Posted (edited)

Couple things -

 

1. How are you connected? RF through channel 2/3 on your TV? Composite?S-video?

 

2. Yes, modern LCDs interpret the NTSC color gamut a bit differently than CRTs do. You can adjust the color potentiometer inside your Atari to tweak the color balance to your liking, but LCDs will always look a little bit different than CRTs, especially through RF or Composite. S-Video (Chroma/Luma) will give better and more accurate color but again CRTs and LCD are just different.

 

 

Sorry meant to mention that last night. Tried connecting two ways. One with a composite video cable direct to video in of the TV, And with RF. Video gives slightly better results.

Edited by spinnaker15136

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I'd bet its the LCD but to be fair the RF and COMP picture directly out of the 800 are not stunningly good, especially compared to today's stuff. The tint sounds like the LCD as said..I have an old LCD TV and it does something similar and more so if you are not square on to the picture..

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There's a very simple video mod for the 800 that involves replacing only 1 resistor:

 

http://atariage.com/forums/topic/198862-atari-800-video-upgrade/?do=findComment&comment=2602329

 

Appears it's only an improvement to S-Video Luma, or not composite.

 

No s-vdeo in on my TV, What is the recommended way to convert s-video today? Get one of those HDMI adapters? Or is there something actually for the Atari out there?

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I'd bet its the LCD but to be fair the RF and COMP picture directly out of the 800 are not stunningly good, especially compared to today's stuff. The tint sounds like the LCD as said..I have an old LCD TV and it does something similar and more so if you are not square on to the picture..

 

 

Yes. Noticed exactly that. If you look at it straight on, it appears to be a bit better.

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If you plan to use the machine with LCD or other modern displays, just go ahead and adjust the color potentiometer inside the 800 and see if you can get close to the correct “NTSC Atari blue.” (*) I take it you probably don’t have access to a SALT or SuperSALT test cart or a color bar generator program. If you do, you can load up the color bar test and adjust to match. If you don’t you can do it the old-fashioned way: load up a game that has pretty well-defined color on-screen at once and and adjust the colors to match. I like to use DIG DUG, JOUST or something like PITFALL. DIG DUG puts a lot of colors on-screen at once; JOUST lets you adjust by looking at the tendency towards green and red/brown; PITFALL lets you adjust to match the rich green of the jungle.

 

The 800 color potentiometer is not accessible without taking the system apart, if I recall correctly. It’s mounted on the vertically-installed “personality board” at the rear of the main board, along with the 6502, ANTIC and GTIA. It’s been awhile since I’ve had one of my 800’s apart though so perhaps there’s an access hole there I don’t recall.

 

(*) I say that because PAL systems have a bit of an aqua tint compared to the deeper blue of NTSC

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If you plan to use the machine with LCD or other modern displays, just go ahead and adjust the color potentiometer inside the 800 and see if you can get close to the correct “NTSC Atari blue.” (*) I take it you probably don’t have access to a SALT or SuperSALT test cart or a color bar generator program. If you do, you can load up the color bar test and adjust to match. If you don’t you can do it the old-fashioned way: load up a game that has pretty well-defined color on-screen at once and and adjust the colors to match. I like to use DIG DUG, JOUST or something like PITFALL. DIG DUG puts a lot of colors on-screen at once; JOUST lets you adjust by looking at the tendency towards green and red/brown; PITFALL lets you adjust to match the rich green of the jungle.

 

The 800 color potentiometer is not accessible without taking the system apart, if I recall correctly. It’s mounted on the vertically-installed “personality board” at the rear of the main board, along with the 6502, ANTIC and GTIA. It’s been awhile since I’ve had one of my 800’s apart though so perhaps there’s an access hole there I don’t recall.

 

(*) I say that because PAL systems have a bit of an aqua tint compared to the deeper blue of NTSC

 

 

There is something on the bottom label. Right under the Atari logo. I have the hole broken out for some reason. Don't think it is a mounting hole. I tried to adjust. Either it is not turning, or it is simply having no affect or my screw driver is .not long enough. I also have one of those non metallic adjustment tools used for the old IF cans in radio and TV. But again not long enough.

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Ah I see it. I popped the hood. There is a hole drilled into the shield right about where I see the hole in the label. It is a coil with an iron core. When I look closer at the bottom I can see a hex iron core. Unfortunately my adjustment tool does not the right size. I am pretty sure I had a whole set of those back in the day.

 

Guess I will need to look at the schematic unless someone can tell me what that coil is.

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Posted (edited)

Wonderful.

 

attachicon.gif0428190748.jpg

 

This is the color pot for the 800..

 

 

Thanks! Well the blue is bluer but still have some of that magenta color in the characters.

 

 

I'll have to get a color bar generator but need to get my SD-Drive Max up and running first. I still might need to resort to the mod posted above.

 

Any idea what the coil adjustment on the bottom was for? I wonder if it was for the RF?

Edited by spinnaker15136

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So what other boards do you have in there? Where is your ROM card?

Looks like he’s got an Incognito board in there - don’t ask; they’re not currently being manufactured. :)

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Looks like he’s got an Incognito board in there - don’t ask; they’re not currently being manufactured. :)

 

 

And from my search it looks like Incognito was to make the Atari 800 compatible with other Atari's?

 

Man I missed out on a lot or have forgotten a lot. ;)

 

Is that the Qmemiry board? Photo is awfully fuzzy. Ar there other boards in there too? Looks like multiple boards in the same slot?

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Any idea what the coil adjustment on the bottom was for? I wonder if it was for the RF?

 

That is for the sound adjustment for differences in TV tuners to get ride of static sounds.

 

David

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Is that the Qmemiry board? Photo is awfully fuzzy. Ar there other boards in there too? Looks like multiple boards in the same slot?

 

The Qmemiry is a CF card that the Incognito uses as a hard-drive(-like) storage. The incognito allows the 800 to run in either original "Colleen" mode or XL mode with the 1MB memory bankswitched either Atari 800 or XL-style. It also allows to switch between various OS versions and run SpartaDOS. Unfortunately it's not currently available new (but might be in the future).

 

The picture above is David-Hamilton-style Atari 800 p*rn...add a Bit3 and even Playboy would find it too lewd to print.

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This might be a good candidate for flashjazzcat's easy video upgrade if you still have your 800 pulled apart. It definitely help with

my 800 'bleeding' character problem.

 

DavidMil

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This might be a good candidate for flashjazzcat's easy video upgrade if you still have your 800 pulled apart. It definitely help with

my 800 'bleeding' character problem.

 

DavidMil

 

 

Just had the cover popped. Main board still in place.

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