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New video upgrade coming soon!

video upgrade clearpic supervideo UAV

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#1 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 1:15 AM

I've been working on a new upgrade that can be installed in any A8, 5200, & even the 2600.

 

I know there's a million upgrades out there, but the good ones are mostly based on tweaks to the original Atari circuit, and the bad ones are haphazardly designed.

 

1st, the real problems with the Atari circuit(s):

 

The video circuits in most A8's are not sufficiently decoupled from the digital noise in the system. Video power and ground are often shared with very noisy components like DRAM and this causes vertical bars to appear in the picture. For example, you can often see the refresh cycles on the left side of the screen. Crude DACs like the one made from the CD4050 have no ability to reject power supply noise and will superimpose it on the picture. No tweaking of the video buffers will remove it. Atari actually put components in some XLs to blur the image in an attempt to clear up the lines.

 

That's not to say the buffers didn't need tweaking. They frequently deviated from the 75-ohm impedance standard that that meant the picture quality could be unreliable (shadows, smearing & ghosting), especially with longer cables. At video speeds, you only get maximum transfer when everything is the right impedance.

 

In addition, some of the chroma circuits produced highly distorted sine-waves which contributed to noise in the image.

 

So to solve these problems, my board:

 

1. Has an on-board regulator to create a clean video power source.

 

2. Has a 3-channel video amplifier designed for 75 ohm loads.

 

3. Has a pixel re-clocking circuit to remove skew and better align the 4 luminance signals into a perfect pixel edge.

 

4. Has a carefully designed chroma-shaping circuit.

 

In addition, there's an adjustable pot on the board which controls the phase between the chroma and luma signals. A nice side-effect of this that you can change the artifact colors. There's also a jumper to invert the chroma which swaps the positions of the artifact colors.

 

The board plugs into the CD4050 socket for easy installation on most machines. It can be used in place of the original circuit or along side it.

 

I'm working on the final board layout and I hope to have them available in the AtariAge store early next year. Here are some pictures of the prototype. Any patterns in the picture are due to the camera picking up the CRT mask, but you'll notice the absence of vertical bars (I'll try to get better pictures...). One of the pictures is taken off my LCD (and even the LCD is hard to photograph). The split screen pictures show the effect of artifact tuning. The board is currently installed in a very noisy 130XE. I'll try to get some before pictures.

 

I'm calling it UAV for Ultimate Atari Video. More to come!

Attached Thumbnails

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#2 KLund1 OFFLINE  

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Posted Fri Dec 11, 2015 1:28 AM

WOW !!!

  Great Upgade!!

Any A8??  400, 600XL?? What will the output connection be? s-video, RGB, HDMI??

Can't wait to see the final version !!!!



#3 Lord Thag OFFLINE  

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Posted Fri Dec 11, 2015 1:52 AM

Neat. If it's easy to install I am down. Keep us posted. 



#4 AtariBuff OFFLINE  

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Posted Fri Dec 11, 2015 2:13 AM

Interested in this one as well, please keep us posted about progress  :)



#5 robc OFFLINE  

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Posted Fri Dec 11, 2015 2:41 AM

I'd certainly be interested in this if it's compatible with PAL machines - would love to improve my 800XL's output quality :)



#6 spookt OFFLINE  

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Posted Fri Dec 11, 2015 7:23 AM

+1 for interest from PAL land :)

#7 adam242 OFFLINE  

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Posted Fri Dec 11, 2015 7:43 AM

Sweet! Love the adjustable artifacting.

I'll be buying at least one for my 1200xl.

If this will physically fit in an 800 under the cage, I'm down for at least one more.

#8 brenski OFFLINE  

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Posted Fri Dec 11, 2015 7:47 AM

please add me for a couple of these, thanks



#9 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 7:58 AM

More info:

 

The board is designed for NTSC or PAL and conforms as closely as possible to those video specifications. Today I'll be transferring it to a PAL machine for more testing. Installation is fairly simple if you have a socketed 4050 and a computer which doesn't obstruct placement of the board. I tried to make it fit as many machines as possible. You do need to install one extra wire to the COL pin of GTIA since it doesn't go to the 4050 socket. If the board doesn't fit your machine, I'll have a stripped down option with the socket header removed. Then you just have to wire up the signals yourself and stick the board somewhere nearby.

 

There's a terminal strip for video out (and the aforementioned COL signal in). It provides the standard Composite video and Chroma/Luma signals. All signals can be used at the same time unlike the original video where the picture is degraded if S-video and Composite are both connected.

 

The jumpers are there because different A8's use the pins of the 4050 differently. They allow you to designate which pins contain which signals. There's also two breakable pads at the front for +5 and GND connections so you can run your own dedicated power connections in case the 5V to the 4050 is bad enough to affect operation. This could happen on some machines which have a high resistance inductor on the 5V supply.

 

-Bry



#10 Larry OFFLINE  

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Posted Fri Dec 11, 2015 8:00 AM

Very nice!

-Larry



#11 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 8:06 AM

Since artifacting isn't really an issue on PAL machines, you can leave the pot in the default position or adjust it for the best looking pixel edges.

 

Too bad there's no easy way to make NTSC artifacting show up on PAL!



#12 Ransom OFFLINE  

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Posted Fri Dec 11, 2015 8:08 AM

If this pans out, I'll buy 3 or 4 of them for sure!



#13 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 8:45 AM

By the way, the 130XE I'm using for this test is the one from this thread:

 

http://atariage.com/...of-130xe-screen

 

post-38669-0-56934100-1394249683_thumb.j
 

I swapped 130XE's with member RCA1802 to analyze the severe video problems of this board revision (that's why you see wire jumpers on the board in my picture of the upgrade). The power routing to video is atrocious. It pulls in grounds from 2 different places (one from the left and one from the VLSI chips to the right) and the 5V comes from the RAM chips to the left. A routing error on the board causes power filtering components to be completely bypassed.



#14 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 3:34 PM

I'm finally getting started testing with PAL. It took a while because BOTH of my PAL machines refused to work for some reason.

 

Now my office looks like the inside of an Atari dumpster.



#15 Triads OFFLINE  

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Posted Fri Dec 11, 2015 3:41 PM

NIce.. Very interested



#16 mytekcontrols OFFLINE  

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Posted Fri Dec 11, 2015 3:43 PM

I want at least two of these when they are available.

 

- Michael



#17 Stephen OFFLINE  

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Posted Fri Dec 11, 2015 5:12 PM

I'll take a minimum of two when available.



#18 Hyperboy OFFLINE  

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Posted Fri Dec 11, 2015 5:18 PM

I would be interested in a couple.

#19 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 6:30 PM

This is the first test on a PAL machine and it looks really nice. I'm going to tweak a couple parts because the chroma signal isn't quite the same level in PAL as in NTSC, but that's more of a nit-pick and won't affect the picture much.

 

Right now this is what I think it will fit: Updated 2/2/16

 

400

Plug in board compatible! Fits in the 4050 socket. Plenty of space in the large shield.

http://www.the-liber...Motherboard.JPG

 

(the 4050 is the rightmost chip)

msg-6732-0-66452300-1453778251_thumb.jpg

 

 

800

Requires the basic board. The 4050 is turned in a way which would face the board into the shield. Will need to be soldered (8 wires) and mounted somewhere.

 

http://www.the-liber...Motherboard.JPG

 

1200XL

Depends. Without the shield, the Plug-In board will fit. Otherwise, there isn't enough overhead space. Might work with a zero-profile socket. 

 

http://atariage.com/...-1347735211.jpg

 

msg-8008-0-63867900-1453731743_thumb.jpg

 

600XL

The Plug-In board can work, but the vertically mounted resistors may need to be bent over which may involve some soldering. The 4050 is to the left of the RF Modulator. The other options are to mount a Basic board, or get above it all with a double socket and forget the shield. 

 

http://atariage.com/...=1#entry2069550

 

800XL

The Plug-In board fits with the taller-type shield and a socketed 4050. It's a little tight with the lower-type shield (if your shield has a bend and a horizontal section in the back, you have the taller shield. The lower shield is shaped more like a wedge). Without the shield, there should be no problem using the Plug-in board. The 4050 is usually just below the RF modulator and usually has an electrolytic cap at its lower left corner.

 

http://atariage.com/...s/#entry2274712

 

65XE/130XE

The Plug-In board requires shield removal. Shield is fairly low but a zero profile socket might work. The 4050 is to the left of GTIA and usually has an electrolytic cap to its left.

 

http://atariage.com/...-1339043189.jpg

 

XEGS

The Plug-In board fits! The 4050 is in the lower right corner. Solder a socket on top.

 

Install shown here:

http://atariage.com/...soon/?p=3389191

 

post-3606-0-50614300-1449881694_thumb.jp

 

5200

The Plug-In board fits! The 4050 is between Antic and GTIA on the right. Board will partially sit over Antic.

 

Install info here:

http://atariage.com/...soon/?p=3412378

 

post-3606-0-56169900-1452442627_thumb.jp

 

2600

If you have a 4050, then you can use the Basic board or the Basic board kit. Otherwise, just the basic board. 

 

Install information:

http://atariage.com/...soon/?p=3411171

http://atariage.com/...soon/?p=3412340

 

Here's an install of a Basic board.

 

post-3606-0-16975400-1452287406_thumb.jp

 

7800

Requires the Basic board. No CD4050 socket.

 

 

Now some PAL pics. Again, you can see artifacts from photographing a TV mask, but the PAL picture is the best I've seen.

Attached Thumbnails

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#20 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 6:55 PM

I just checked and the XEGS is no problem. You can solder a 16p socket directly over the 4050 if you have the vertical clearance.

 

 

Attached Thumbnails

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#21 Mathy OFFLINE  

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Posted Fri Dec 11, 2015 7:17 PM

Hello Bryan

 

Just to check that I understand what you're saying:

 

- Your upgrade replaces the 4050.

- We don't need another video connector.  The upgrade improves the signals on the existing monitor jack (but not the signal at the RF-modulator).

 

BTW how hard would it be (for the average solder jockey) to replace the jumpers with wires and the green connector?

 

Sincerely

 

Mathy



#22 pboland OFFLINE  

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Posted Fri Dec 11, 2015 7:21 PM

I just checked and the XEGS is no problem. You can solder a 16p socket directly over the 4050 if you have the vertical clearance.

 

 

Cool upgrade!

Do you happen to have side by side pictures of the screen for the XEGS. I only ask because out of all the atari 8-bit computers I've used (1200XL, 800XL, 600XL & XEGS) the XEGS has the best composite out put of any of them. I always felt the XEGS image to be quite clear. I was just wondering how much better the screen image looks with your upgrade.



#23 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 7:28 PM

Hello Bryan

 

Just to check that I understand what you're saying:

 

- Your upgrade replaces the 4050.

 

It picks off all the signals and power from where they enter the 4050 except the color output from GTIA Pin 21, which requires a wire. The 4050 can be easily removed if it's socketed, or a socket can be soldered on top of it if you have the vertical space for the extra height this causes.
  

- We don't need another video connector.  The upgrade improves the signals on the existing monitor jack (but not the signal at the RF-modulator).

 

The video output is the green terminal block. To use the existing DIN video connector, you would need to run wires to it. If the 4050 is removed, then the on-board video is disabled. If the 4050 is left in, then on-board video is unaffected. For the cleanest installation, I'd run the wires to the DIN jack.

 

BTW how hard would it be (for the average solder jockey) to replace the jumpers with wires and the green connector?

 

Sincerely

 

Mathy

 

I'm not sure what you're asking. Do you mean replace the configuration jumpers?

 

-Bry



#24 Mathy OFFLINE  

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Posted Fri Dec 11, 2015 7:33 PM

Hello Bryan

 

If the configuration jumpers are the two rows of ten pins each then yes, that's what I was asking.

 

Sincerely

 

Mathy



#25 Bryan OFFLINE  

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Posted Fri Dec 11, 2015 7:45 PM

Cool upgrade!

Do you happen to have side by side pictures of the screen for the XEGS. I only ask because out of all the atari 8-bit computers I've used (1200XL, 800XL, 600XL & XEGS) the XEGS has the best composite out put of any of them. I always felt the XEGS image to be quite clear. I was just wondering how much better the screen image looks with your upgrade.

 

Hope this helps. However, remember this is still a prototype.

Attached Thumbnails

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