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Bryan

New video upgrade coming soon!

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If I understand you correctly, that distance from the center of the hole to the 90-deg corner is 45mm. This is the area directly above (behind?) the 4050...

attachicon.gifref0.jpg

 

(parallax again, the corner was aligned with the 20cm mark on the ruler)

attachicon.gifref.jpg

 

What I meant was, if you look at the underside of the metal shield at the hole that matches the one behind the 4050, how far is it from the center of the hole to the 90 bend upwards. In other words, when the shield is installed how much of the exposed metal grounding strip does it cover? I was just curious if there's any extra room there or not. I'm also working on shrinking the board a little.

 

Thanks for taking these pictures for me!

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What I meant was, if you look at the underside of the metal shield at the hole that matches the one behind the 4050, how far is it from the center of the hole to the 90 bend upwards. In other words, when the shield is installed how much of the exposed metal grounding strip does it cover? I was just curious if there's any extra room there or not. I'm also working on shrinking the board a little.

 

Thanks for taking these pictures for me!

 

ah, that makes more sense...

 

Looks like there's 5-6mm between the center of the hole and the upturned edge of the shield:

post-19239-0-76003600-1450028291_thumb.jpg

 

Which unfortunately will cover the entire width of the strip on the PCB:

post-19239-0-50845600-1450028297_thumb.jpg

 

No problem, glad to help...

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Looks like there's 5-6mm between the center of the hole and the upturned edge of the shield:

 

Which unfortunately will cover the entire width of the strip on the PCB:

 

I was able to shave a little more off the length of the board, so I think it'll be okay. I'll probably recommend putting a piece of tape on the inside of the shield so a little bit of stray wire doesn't short out the video.

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I was able to shave a little more off the length of the board, so I think it'll be okay. I'll probably recommend putting a piece of tape on the inside of the shield so a little bit of stray wire doesn't short out the video.

 

Or just leave the shield off entirely... it's not a load-bearing structural piece like the 400 and 800 cages.

 

My modded 1200XL has been shield-less and trouble-free for years.

Edited by adam242

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Or just leave the shield off entirely... it's not a load-bearing structural piece like the 400 and 800 cages.

 

My modded 1200XL has been shield-less and trouble-free for years.

I agree. Unless you plan to use the RF output, the shield doesn't buy you anything. And yes I too leave the shields off as well, since it makes changing things so much easier in the future.

 

- Michael

 

Edit: Perhaps back in the old days when people used rabbit ears to watch TV it made a difference, or when trying to pull in a very distant station on your radio (also with an antenna), that the RF shields would be useful.

Edited by mytekcontrols

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Well, it also looks like a tight fit in the 2600jr, so every bit helps. I want this thing to be as tiny and easy as possible. :) New board revision is 90% done. Hopefully this one will be the last.

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I'd like to try this mod in my 7800!

 

On my 7800, I removed U3 and put in jumpers that only connect Maria to the ouput. A lot cleaner on the RF!

 

I'm not interested in playing 2600 games on it anyway.

 

One mod for the 7800 by the Longhorn Engineer uses a 4050 if I remember correctly.

 

If it doesn't work, I have a 5200, Sears Video Arcade II I could put it in!

post-7077-0-95589500-1450070004_thumb.jpg

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I'd like to try this mod in my 7800!

 

On my 7800, I removed U3 and put in jumpers that only connect Maria to the ouput. A lot cleaner on the RF!

 

I'm not interested in playing 2600 games on it anyway.

 

One mod for the 7800 by the Longhorn Engineer uses a 4050 if I remember correctly.

 

If it doesn't work, I have a 5200, Sears Video Arcade II I could put it in!

 

You can manually wire it into a 7800 and it should work. You can even keep 2600 compatibility if you use the output of the or gates.

 

-Bry

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Final board changes are done (hopefully). I'm trying to select a new board house after Myro screwed up my last order.

post-3606-0-03181000-1450201637_thumb.jpg

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I need this mod. The 130XE that I got for my son shows vertical lines. The ebay seller mentioned that RAM chips were replaced with good NEC chips and socketed. From some other Bryan's posts I get that the vertical lines are caused by the digital noise generated by RAM chips, because 130XE power lines are shared with the video circuits. I read through the thread with RCA1802's vertical lines issues where a suggestion was attempted to cut power around L5 and throw wires from the power switch that didn't result in an improvement.

 

This makes me wonder, how does this board solve this issue?

Where is it supposed to get its power, from the power switch?

Does it have a built-in noise filters for the power lines?

Is the true nature of the vertical lines different from the RAM noise, so the board have to do something special?

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I need this mod. The 130XE that I got for my son shows vertical lines. The ebay seller mentioned that RAM chips were replaced with good NEC chips and socketed. From some other Bryan's posts I get that the vertical lines are caused by the digital noise generated by RAM chips, because 130XE power lines are shared with the video circuits. I read through the thread with RCA1802's vertical lines issues where a suggestion was attempted to cut power around L5 and throw wires from the power switch that didn't result in an improvement.

 

This makes me wonder, how does this board solve this issue?

Where is it supposed to get its power, from the power switch?

Does it have a built-in noise filters for the power lines?

Is the true nature of the vertical lines different from the RAM noise, so the board have to do something special?

 

There is a voltage regulator on the board to create a local filtered supply for the logic ICs. This way, the video DAC isn't being fed system noise. The regulator can pull power from the CD4050 socket and that will usually provide good results, but those connections don't have to be used if your board is especially noisy and you want to run power directly from the power connector area.

 

RCA1802's board had additional problems with routing mistakes and the fact that the CD4050 ground isn't even the same one used by the rest of the video circuitry and is instead pulled from the VLSI chips to the right. That's why I got that computer from him, I knew something else was up.

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I thought that this item is going to be offered through the AtariAge STORE..., BUT if that is not so, then I will order 2 (two)..

I think that was and likely still is the OP's intention, but until that happens people like myself are just letting him know we are interested and ready to buy. It also allows him to better gauge what might be an appropriate production board run.

 

- Michael

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Well, after messing with this some more, it looks like the artifacting range is going to be from the XL's purple/green to the XE's red/blue. I really wanted to support the exact green/blue of the 800 but it isn't possible without a lot more complexity. Here's the situation:

 

The NTSC color wheel:

phase_colour_wheel_big.jpg

 

To get the 65/130XE colors, draw a line through the middle from red to cyan. To get the 800XL and XEGS colors, spin the line clockwise to magenta and green (about 40ns difference). Now look at the 800 colors- blue and green. You can't get there with a line through the middle. They're only about 130° apart and seem to be the result of some unique distortion in the 800's video or clocking circuits.** There is nothing I can do on my board to get them right and I don't think it's worth making a bigger, costlier, and more complicated board.

 

See this post for more info:

http://atariage.com/forums/topic/204355-artifacting-isnt-it-weird/?p=2624664

 

Currently, I can produce the colors from every machine in that list other than the 800, and I can swap the colors as is required for the 1200XL and 600XL (and to emulate using a CTIA).

 

Opinions?

 

 

**The 800's color alignment is actually very close to the 800XL's purple/green (but inverted) as both machines have very fast color buffers. I don't yet know exactly why odd bit patterns end up skewed. My gut suspicion is that the system clock is not very close to 50/50 duty cycle and even and even/odd pixels end up being different sizes.

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I just want something that'll produce clean video out of my Atari. Emulating different artifacting to match different models is not very high on my list, although it could be to others. Since you have already made it possible to match up with everything other than the classic 800, making it bigger and costlier just to do this really doesn't seem like the right priority.

 

- Michael

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Most of us probably need at least one of these, myself included. 'll start with one and probably bug Albert to produce more through the store, later. Artifacting is a nice extra, if rarely used. Nice to have a standard to code/work to.

 

Would this work with the proposed Interlace Mod?

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