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Osxster

Atari 800 Video Issues

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Hello,

 

I just picked up an Atari 800 from EBay. The thing seems to work mostly, however when I noticed that I first hooked it up to an S-Video to VGA adapter, the screen got very white, washed out. At first it almost looked like it had no color. I played with the POT adjustment and got a little more blue out of it, but it still doesn't look like my 130XE. When I hook up the S-Video to a regular TV, I thought it looked better and was thinking the signal strength of the Atari 800 was over powering the S-Video to VGA adapter. But upon further investigation, some of my Red isn't really coming out right. Playing MS-PacMan, there is absolutely no pink at all even when I play with the POT adjustment. My Pinky ghost is white! The walls never get full red. There is no self test on the 800 so I am not sure what utility yet to use to display a full pallet of colors to see exactly what I am missing though.

 

If I connect Composite out to a monitor / TV, the colors look fine. So it is just the Chroma and Luminance that is not displaying reds properly and seems to give me a whiteish washed out picture connected to a VGA converter. All of the black background becomes whitish too instead of a picture on a black background using this adapter. The same cable combination on an Atari 130XE is fine.

 

Does anyone know where to begin troubleshooting what is causing this? I bought an Atari 800 for four joystick support, but it bothers me that the colors are messed up. Any help would be great.

 

Osxster

 

 

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Can't help, but if you aren't able to fix it, it may be worth - very worth - to catch up one of the Super Color CPU Card

Got three for my 400 and 800s and the resulted quality is superb!

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A few notes:

 

The 800 and the VGA converter need to be the same video system (both PAL, or both NTSC).

There is no self-test in a stock 800.

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From reading that link, he claims his board is on par with the Atari 800 graphics. Thus it may not improve video at all over a stock 800. I guess if its likely my graphics card, I've seen replacement "fully tested" graphics boards with GTIA and all other chips for like $20. It might be worth buying that unless it could be something else that is bad. I have not opened it yet to see if there is anything obviously bad, but if generally this type of failure is the graphics card, it might make sense to buy a cheap one which was supposedly fully tested. Any hints on what could cause these types of problems would be greatly appreciated.

 

Osxster

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From reading that link, he claims his board is on par with the Atari 800 graphics. Thus it may not improve video at all over a stock 800. I guess if its likely my graphics card, I've seen replacement "fully tested" graphics boards with GTIA and all other chips for like $20. It might be worth buying that unless it could be something else that is bad. I have not opened it yet to see if there is anything obviously bad, but if generally this type of failure is the graphics card, it might make sense to buy a cheap one which was supposedly fully tested. Any hints on what could cause these types of problems would be greatly appreciated.

 

Osxster

The card with the GTIA/ANTIC is not the cause of bad video on the 800. It's the inbuilt video circuitry, which this card will bypass. AA member Bryan was kind enough to allow the use of his "UAV" board in this card. Without utilizing Sophia of VBXE2, this will give you the absolute best output signal from the Atari which is possible.

 

I have installed the UAV in several machines for myself and customers, and I am also using this card in my 800 with Incognito. I cannot be happier with the output quality.

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Im not sure he even sells those cards any more since they were a prototype. But in any event, does anyone think my problem is in that board? Will a replacement video card fix it? Could there be circuitry on the main board that could cause this issue?

 

Osxster

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Here's a .ARC of an .ATR with 'TWO56CLR.BAS' that will give you a full colors screen.

 

Atari used .ARC, it was before .ZIP compression.

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Here's a .ARC of an .ATR with 'TWO56CLR.BAS' that will give you a full colors screen.

attachicon.gifGRSN1A.ARC

Atari used .ARC, it was before .ZIP compression.

I see this has no attached file. I don't know how to do it..... I think I did it this time.

GRSN1A.ARC

Edited by russg

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Could there be circuitry on the main board that could cause this issue?

You could have a bad 4050, A103 that might behave as

your symptoms show. You don't have a replaceable

'board' for video to replace as it were, discrete parts

here and there yes, but no video only system board.

 

eBay would be just one source for a 4050 chip.

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4050 chips are still used today. New production chips are available from any electronic retailer (Mouser, Digi-Key, Jameco, etc). I bought a few to repair an 800XL of mine a few years back. They were about 45 cents apiece at the time, plus shipping.

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This was fun actually, it has been 30 years since I loaded a program from basic on an Atari computer. Its all coming back.. Maybe 23 years since I used ARC. Anyway it seems like the colors work with Chroma Luminance, but when the red color get too pink, it turns white instead. Some of the blue seems to turn white also when its supposed to get darker. See attached images from my TV...

 

Both of these images are from the same Atari 800, just I only have this problem with Chroma Luminance. Composite works color wise, but the quality of composite on this TV is poor, so it looks like crap. But the colors are there. This same thing works fine on an Atari 130XE with the same TV / cables. Hooking this up to an SVideo to VGA converter gives you a very white image overall.

 

Could this be a bad 4050 chip causing this?

 

Osxster

 

post-62878-0-63754600-1526331480_thumb.jpg

post-62878-0-71456900-1526331496_thumb.jpg

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Hello,

 

I just ordered a 4050 chip and replaced it on the mother board. While the chip seems to work, I still get the exact same problem with my video. Does anyone have any clues on where to look next? Any other clues would be very helpful. Thanks for your help so far.

 

Osxster

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You are welcome. We try what we think might be it, and

often that isn't it.

 

So there is a 3086 as A104 that might be funky. These

are known to 'go south' in other Atari circuits as

well, I have plenty of these as spares. Two in the

1050 drive for example.

 

SALT cartridge has some grey and color tests in it,

there may be a .XEX of it about. Field Service Manual

is a how to as far as the SALT tests go.

http://www.atarimania.com/documents/Atari_400_800_Field_Service_Manual_June_82.pdf

 

Atari SALT diagnostic CART v2.05 (1982).xex

http://atariage.com/forums/topic/277122-early-800-only-showing-bw/?do=findComment&comment=3996311

 

Not trying to run you off, you are just outrunning my

experience rapidly at the moment. Will still chime in

when I think it might help.

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Hello,

 

Are there any 3086s in 810 drives? I have a few of them laying around, I dont really want to take apart my happy 1050s as they both work nicely. Otherwise Ill see if I can find the 3086 on eBay or someplace. I dont have any cartridge emulators but it looks like I have an ATR of SALT. I guess I can try that and report what it comes up with. Thanks.

 

Osxster

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Yep, A106 on the side board is a 3086 in the 810.

But cheated and had to look it up. Have one or two,

I forget exactly, never used it (them).

 

The .XEX linked to above is the file version of SALT

if you can use that method. Instead of .exe for

executable file, the extension has been renamed for

emulator use mainly, but it's still just an executable

file you load with DOS.

 

Sorry if I'm telling you stuff you already know, but

the hiccup between Russ's offerings of an ARC above

which you work and like, and then the ATR suggestion

you made last has me wondering if you know that the

ATR you have may have the very same .XEX file on it?

Could have a different name like autorun.sys, but I

don't know your ATR at all.

 

Of course I know nothing of how it is at your place,

or your support gadgets and/or methods of getting data

from PC to Atari. It's a many layered onion and there

are so many ways to skin this cat I won't hazard a

guess. With your low post count also we can't be sure

of how fluent you are in modern day Atari.

 

Tell us how you get files from PC to Atari and we'll

know, only if it's a relative thing that needs doing.

Otherwise I'll just assume being sort of new here you

just didn't know that the .xex linked to was a file.

It only emulates the cartridge it's named for, very

much like an ATR would have to do it too.

And not big deal either way. I detect you are

pretty sharp and had talents back in the day.

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Sorry I was unfamiliar with the extension and didnt realize .xex was an Atari .exe file. I assume to prevent it from showing up as a malicious windows file. I am not at all new to the Atari scene as I ran an Atari BBS with an ATR 8000 with 1.2 MB and 8 inch 1mb drives before going to an ICD Multi IO with a few hundred megs in Hard Drive space. I eventually added ST and Amiga before moving it to an ST and then a PC multi node setup. I use to move everything over through the BBS via null modem, but Im now using in my simplified Atari setup an AtariMax SIO2serial adapter connected to a Mac Mini server with respeqt. Its been a very long time since using this stuff, so Im new to the modern era of Atari, but its all coming back. I have the Holmes Atari archive of stuff, which is a lot easier to go through than hundreds of floppies, but I still have most of my stuff from the day. Some of it is still at my parents house. Never used Salt before though.

 

Ill try salt and see what it comes up with. I have my fathers two Happy 810s which I brought home with my stuff which havent been powered up in 30+ years, I could use one of them as parts to troubleshoot this issue if need be. Then buy a new chips to replace it if this solves the problem. If I need to tear it too much apart, Ill just buy new chips.

 

Osxster

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Hello,

 

I just picked up an Atari 800 from EBay. The thing seems to work mostly, however when I noticed that I first hooked it up to an S-Video to VGA adapter, the screen got very white, washed out. At first it almost looked like it had no color. I played with the POT adjustment and got a little more blue out of it, but it still doesn't look like my 130XE. When I hook up the S-Video to a regular TV, I thought it looked better and was thinking the signal strength of the Atari 800 was over powering the S-Video to VGA adapter. But upon further investigation, some of my Red isn't really coming out right. Playing MS-PacMan, there is absolutely no pink at all even when I play with the POT adjustment. My Pinky ghost is white! The walls never get full red. There is no self test on the 800 so I am not sure what utility yet to use to display a full pallet of colors to see exactly what I am missing though.

 

If I connect Composite out to a monitor / TV, the colors look fine. So it is just the Chroma and Luminance that is not displaying reds properly and seems to give me a whiteish washed out picture connected to a VGA converter. All of the black background becomes whitish too instead of a picture on a black background using this adapter. The same cable combination on an Atari 130XE is fine.

 

Does anyone know where to begin troubleshooting what is causing this? I bought an Atari 800 for four joystick support, but it bothers me that the colors are messed up. Any help would be great.

 

Osxster

 

 

 

The Atari has a non-standard video level, which causes problems on some displays. What you find is the TV/monitor needs to be adjusted to match the Atari rather than trying to tweak the Atari to match the display.

 

The best way to adjust Brightness, Contrast and Hue is to use the SALT cartridge. Set the brightness for deep black on the left edge of the LUM bars and contrast to max white on the right edge. Set the top and bottom bars to the same color using the COLOR adjustment. -- all on the TV.

 

If you adjust your display for an 800, the display will look terrible on a 130XE - you can help that by adding a 75 ohm resistor to the LUM in the Atari. (to ground)

 

You don't look 'broken' to me... you just need to adjust a few things.

 

Bob

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Over-driven Luma (factory-installed), which can only be seen when feeding your viewing-display / video-processor with Y/C signals from monitor port.

 

The solution, here, Step I.6, upgrading resistor R189 (you do not need to do ANYTHING else beyond this):

 

http://atariage.com/forums/topic/212773-incognito-install-a-collectors-perspective/?hl=%2Bincognito+%2Bcollector&do=findComment&comment=3433380

 

 

Board Location:

 

post-29379-0-17260200-1527099118_thumb.jpg

 

 

 

Results:

 

post-29379-0-83733700-1527098702_thumb.jpg

 

post-29379-0-42387800-1527098788_thumb.jpg

 

 

Enjoy!

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