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better atari 5200 s-video mod


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#1 low_budget OFFLINE  

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Posted Sun Jan 29, 2012 8:09 PM

Several months ago I did a s-video mod using the 5200 faq and found it had a few errors that were adding interference to the signal. While the guide got the job done, it looked BAD on a LCD TV. Following the guide didn't really seperate the chroma, luma, and sound at all. The solder points were labeled wrong. Plus, the circuit didn't output composite video, which I wanted.
I got the results I wanted by first isolating the luma / chroma / audio on the board. The biggest improvement over the original guide came when I removed R31 (6.8k) at the top right of the area covered by RF shielding. That isolated the amplified chroma signal. Then I removed all 7 resistors at the top right to isolate the luma from the audio and modulation circuit. The FMS6400 improved the picture a LOT and added composite video.
I figured out how to use PCB design software then I made some prototypes and now I'm at version 1.2 after fixing some issues with the composite video.

I posted the schematic I use on my v1.2 boards and the corrected solder points.


I am also working on a more complex s-video circuit that would connect directly to the GTIA on the 5200 and Atari 8 bit computers. This should give the best possible picture quality from these systems. I have the PCBs on order and will begin testing soon.

Attached Thumbnails

  • ATARI 5200 SVID schematic.JPG
  • atari5200guideS.JPG

Edited by low_budget, Sun Jan 29, 2012 8:11 PM.


#2 Ransom OFFLINE  

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Posted Sun Jan 29, 2012 8:15 PM

Excellent! If you decide to sell mod boards, let me know. :)

#3 fernando marrin OFFLINE  

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Posted Tue Jan 31, 2012 7:57 PM

didn't install your board yet,
any improvements beyond the 200 faq mod i also have?

#4 Prab OFFLINE  

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Posted Wed Feb 1, 2012 5:19 AM

Hi, in the UK we never got the 5200, so if i import one i could not tune it in on my TV set, if i bought one state side, could i ship it to you and pay for it to be modded? my tv will display ntsc signals which come over composite & s video etc

Prab

#5 Cafeman OFFLINE  

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Posted Wed Feb 1, 2012 10:33 AM

That is an impressive little feat, figuring out the errors on the 5200 FAQ, improving the design, and working on your own PCB solution. (!) I never learned much about electrical engineering or electronics and I always wish I had.

My 5200 has default (crappy) RF output , that's all I've ever known. Although I now hook it to a VCR and output composite to my plasma.

My plasma doesn't have an S-video port , so I'd have to use composite. Does the mod stop the color bleed entirely? For example, River Raid's land edge always has a bold reddish 'edge' as it changes to the blue river.

#6 low_budget OFFLINE  

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Posted Wed Feb 1, 2012 7:07 PM

I never even thought of selling these at first. I modded a 5200 with s-video using the original FAQ and tested it on a tube TV. It looked prettty good so I decided to sell it on ebay. It sold, and I decided to re-test it before shipping. That's when I discovered problems... Mostly the picture had interference and didn't even look better than RF. My first thought was to cancel the sale since the buyer probably wouldn't be satisfied. Then I decided "no, I can fix this."
I was standing on the toilet, and I was hanging a clock, and fell, and hit my head on the sink. And that's when I came up with the idea for the Flux Capacitor, which makes Atari s-video mods possible.
Actually, I looked over the Atari 5200 schematics, and was able to locate my tap points on the schematic. Then I noticed the chroma and luma signals were mixed on board and knew that they had to be isolated. I found the resistor that connected the two signals and removed it. That made the picture quality much better on a LCD TV and now the Atari was suitable for sale. I started coming up with ideas to make the picture even better. I read up on the FMS6400 series chips, and decided to make prototype boards with the new chip. I found PCB design software easy to use because I had a background in CAD drawing. The first version board was rough and offered better picture, but was large and had poor composite output. I eventually read the ENTIRE FMS6400 datasheet and found it needed two power filtering capacitors mounted close to the chip. I corrected that with version 1.1 and found a drastic improvement with composite video, and was able to make the board 1/2 in shorter with the same number of components. I sold these 3 rather quickly and found nobody else was currently selling a similar product for the 5200. I decided to get a quantity of boards using ExpressPCB once again, only I found the pricing to be rather high. I tried Pad2Pad and had to learn their software and re-draw my circuit, but found them to be much cheaper. I made some more improvements and had my v1.2 board produced, this time with professional looking silk screen.
There are some issues still present with the v1.2 boards, but very minor. There is very slight color bleed with composite video, but is only noticable upon close inspection on a large TV. Frogger had some graphics glitches with composite video, but s-video looked near perfect. I think these are issues caused by tapping the signals after going through many of the original on-board components in the Atari, and could not be fixed with a new circuit using the current tap points. This is why I'm working on a circuit that would connect directly to the GTIA and bypass all the original video modulation circuitry with my own. This circuit would be larger and require bending up 6 pins on the GTIA so I hope to offer both kits in the future.
I did reluctantly sell a kit to a guy in the UK after he informed me there was no PAL version of the 5200 (didn't know that) and he had a NTSC compatible tv. He was happy with it so I'd be open to selling kits overseas, but I would rather not offer a modification service.

#7 fernando marrin OFFLINE  

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Posted Thu Feb 2, 2012 6:39 AM

Installed, quality was identicall to my home-made pcb av mod, based on the corrected 5200 faq

Good on crt tvs, some bleeding and deflection problems, but way better than rf,

It's a whole new system compared to stock ouput,
In fact it looks better than my 130xe with av out

#8 fernando marrin OFFLINE  

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Posted Thu Feb 2, 2012 6:40 AM

In fact if you connect it to an hdmi 1080 p upsampler box ,
Looks great on hdtvs,

Though not as great as crt

#9 Ransom OFFLINE  

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Posted Thu Feb 2, 2012 7:53 AM

I'm looking forward to version 1.3 (or 2.0?). :)

#10 Gandor OFFLINE  

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Posted Thu Feb 2, 2012 10:58 PM

Hi,

I bought one of these mods and I need to find some additional material:
- what size (AWG) electric wire is being used and what would be a good place to buy this wire in different colors?
- where to buy the RCA/S-VHS connectors to mount in the case?

I looked at digikey and mouser but there is just too much info and I never seem to be about the find what I'm looking for.
I looked at my local Frys but wasn't able to find it their either.

Thanks

#11 killersquirel OFFLINE  

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Posted Thu Feb 2, 2012 11:31 PM

I would definitely be interested in purchasing any new mods for the 5200 once they become available.

-mike

#12 low_budget OFFLINE  

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Posted Fri Feb 3, 2012 2:14 PM

I've been selling the v1.2 mod on ebay for the last couple months as a bare board or fully assembled.

I normally buy parts from Digikey, the part #s for the output jacks is listed below.
4p mini DIN (s-video jack) CP-2840-ND
Yellow RCA (composite) CP-1415
White RCA (audio) CP-1414
I would recommend 24-26 gauge wire for the connections to the mod board. Some electronics stores sell wire wrapping kits with several colors wire. To connect the video out jacks I like to use shielded wire, usually from a old RCA cable cut up.
If I get another 5200, I will try to do a installation how to video and post on youtube.
It will be at least 2 weeks before I get my circuit boards in for the v2.0 mod kit. When they come in I will assemble one and do some testing and might need to change some components. My guess is they won't be available for sale until March or April.
Some details about v2.0:
Board will measure 1.75in by 2.125 in.
Circuit is based largely on the Atari 800, but has changes to provide better picture than an original 800.
It will connect to 6 lifted pins of the GTIA or CTIA.
Should work in all 5200 systems and most 8 bit computers (if the board will physically fit in these systems.)
I like to use 1/4w resistors to make finding the right values easier, even if this makes the board bigger.
Features dual sided ground planes for minimal RF interference.
V2.0 is a larger board with more components, so it will cost more than my v1.2 kit.

I will post updates as they come.

#13 Ransom OFFLINE  

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Posted Fri Feb 3, 2012 3:04 PM

V2.0 is a larger board with more components, so it will cost more than my v1.2 kit.


So, you're saying there will finally be a reason for that huge 5200 case? :P

#14 Gandor OFFLINE  

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Posted Fri Feb 3, 2012 7:57 PM

I've been selling the v1.2 mod on ebay for the last couple months as a bare board or fully assembled.

I must have bought the assembled and bare boards from you ;-)
Hopefully I'll be able to install it this weekend if I can get the remaining parts.

I normally buy parts from Digikey, the part #s for the output jacks is listed below.
4p mini DIN (s-video jack) CP-2840-ND
Yellow RCA (composite) CP-1415
White RCA (audio) CP-1414
I would recommend 24-26 gauge wire for the connections to the mod board. Some electronics stores sell wire wrapping kits with several colors wire. To connect the video out jacks I like to use shielded wire, usually from a old RCA cable cut up.

Thanks for the part #s, I'm putting in an order tonight.

G.

#15 MarlboroMan OFFLINE  

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Posted Sat Feb 4, 2012 11:53 AM

I just wanted to add that I purchased one of these boards and had it installed at local shop.

The video quality is excellent and it works very well.

According to the guy who did my installation, it was pretty easy to install and it went without any problems.

I would reccomend this kit to anyone who needs to add video out support for their 5200.

#16 venom4728a OFFLINE  

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Posted Tue Feb 7, 2012 7:10 PM

I am also interested in one of these boards.

Robert

#17 atari2atari OFFLINE  

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Posted Wed Feb 8, 2012 3:26 PM

I've been selling the v1.2 mod on ebay for the last couple months as a bare board or fully assembled.

I normally buy parts from Digikey, the part #s for the output jacks is listed below.
4p mini DIN (s-video jack) CP-2840-ND
Yellow RCA (composite) CP-1415
White RCA (audio) CP-1414
I would recommend 24-26 gauge wire for the connections to the mod board. Some electronics stores sell wire wrapping kits with several colors wire. To connect the video out jacks I like to use shielded wire, usually from a old RCA cable cut up.
If I get another 5200, I will try to do a installation how to video and post on youtube.
It will be at least 2 weeks before I get my circuit boards in for the v2.0 mod kit. When they come in I will assemble one and do some testing and might need to change some components. My guess is they won't be available for sale until March or April.
Some details about v2.0:
Board will measure 1.75in by 2.125 in.
Circuit is based largely on the Atari 800, but has changes to provide better picture than an original 800.
It will connect to 6 lifted pins of the GTIA or CTIA.
Should work in all 5200 systems and most 8 bit computers (if the board will physically fit in these systems.)
I like to use 1/4w resistors to make finding the right values easier, even if this makes the board bigger.
Features dual sided ground planes for minimal RF interference.
V2.0 is a larger board with more components, so it will cost more than my v1.2 kit.

I will post updates as they come.


Well, hello! Excellent to meet you, and your mod! :D

Thanks for the hard work of puzzling this all out - - I'll be interested to see what version 2.0 looks like!

I note that the process of installing the mod board disables the ability to use the ATARI 2600 adapter - - do you think that in later versions of the board, that might change, and the compatibility will come back?

Or, in order to get this to work is it just a necessity and "how it is" - - I assume there are some traces to cut or things to desolder in the process of installing that makes it incompatible?

-a2a

#18 low_budget OFFLINE  

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Posted Wed Feb 8, 2012 3:36 PM

I made some small changes to the circuit today and updated the schematic. It turns out the 75 ohm resistors to ground on the outputs are totally unnecessary. My first version circuit board had them tied directly to the outputs of the FMS 6400, but I found it caused an unnecessary load on the chip and made it hot enough to fry an egg. The v1.1 and later had them after 75 ohm resistors on the video output side of the circuit. Today I removed them and found that they didn't seem to have any effect, so I won't install them anymore on future 5200 s-video kits. If somebody that already bought a kit wants to make this change, it's easy, just cut and remove 3 resistors. I didn't notice a big effect on picture quality, but I think it does improve it some.

I also corrected a mistake on my older schematic. Pin 2 of the FMS6400 should be connected to 5v instead of ground for the best picture.

Due to the design of the 2600 adaptor, I decided it's not really practical to make my mod work with it. The adaptor would require internal modificaions. The Atari 5200 doesn't seem to have been designed for any backward compatibility. It was only after Colecovision released their 2600 expansion module 1 that Atari decided to make one for the 5200. The adaptor is almost a standalone Atari 2600 and only uses the RF box and 5v regulator in the 5200.

It would probably be easier and better to install LHE or Batari's 2600 mod kit in the adaptor itself. If you were going to do that, you might as well add a power jack and 5v regulator to make the adaptor a standalone system.

Attached Thumbnails

  • ATARI 5200 SVID CIRCUIT v1_2.JPG

Edited by low_budget, Wed Feb 8, 2012 4:19 PM.


#19 atari2atari OFFLINE  

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Posted Wed Feb 8, 2012 5:58 PM

Due to the design of the 2600 adaptor, I decided it's not really practical to make my mod work with it. The adaptor would require internal modificaions. The Atari 5200 doesn't seem to have been designed for any backward compatibility. It was only after Colecovision released their 2600 expansion module 1 that Atari decided to make one for the 5200. The adaptor is almost a standalone Atari 2600 and only uses the RF box and 5v regulator in the 5200.

It would probably be easier and better to install LHE or Batari's 2600 mod kit in the adaptor itself. If you were going to do that, you might as well add a power jack and 5v regulator to make the adaptor a standalone system.


Ah-ha, thanks for that info! Good to know that it really is sending it all directly to the RF adapter, and THAT is what is being bypassed here.

Not that I *need* the ATARI 2600 adapter to work for the 5200 - - it's not like I don't have enough things around as it is that are quite capable of running 2600 carts - - I was just curious!

Yes, those stand-alone VCS Adapter mods are very cool! I might give that a go, after I clear my deck of the current queue of soldering that seems to be piling up on the workbench . . . !

I'll subscribe to this thread, and keep an eye out for when the ver 2 board is released.

Thanks again for your AWESOME contribution to the community - - it's excellent!

-a2a

#20 low_budget OFFLINE  

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Posted Thu Feb 9, 2012 12:04 PM

Thanks for the support everyone!

I just found out some differences between the 2 port and 4 port Atari 5200 systems after helping somebody with an installation problem. They weren't getting color in the picture after installing the mod in a 4 port system. It turns out the locations of R31 (6.8k) and R33 (510 ohm) were swapped. So my above solder points apply to the 2 port system, while the 4 port Atari needs the chroma wire connected one hole to the left (still at the bottom side of R31.) The other solder points are the same. It also seems the 4 port system has a couple ICs and other components in a spot that is open on my 2 port system. The mod board will still fit on 4 port systems, just not quite as easily. Going to update my install instructions again....

#21 Gandor OFFLINE  

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Posted Thu Feb 9, 2012 2:50 PM

Thanks for the support everyone!

I just found out some differences between the 2 port and 4 port Atari 5200 systems after helping somebody with an installation problem. They weren't getting color in the picture after installing the mod in a 4 port system. It turns out the locations of R31 (6.8k) and R33 (510 ohm) were swapped. So my above solder points apply to the 2 port system, while the 4 port Atari needs the chroma wire connected one hole to the left (still at the bottom side of R31.) The other solder points are the same. It also seems the 4 port system has a couple ICs and other components in a spot that is open on my 2 port system. The mod board will still fit on 4 port systems, just not quite as easily. Going to update my install instructions again....

Good to know because I was about to install the mod in my 4 port 5200.

#22 MrEd OFFLINE  

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Posted Thu Feb 9, 2012 4:47 PM

I double sticky taped the mod board right on top of a couple IC's inbetween the two large IC's.
This worked out great as long as you can live without the RF shield, not needed anyway.
Plenty of space between the case cover and mod board.
I went ahead and joined the forums last night since at some point I'll be doing a 2600 for myself.

Thanks again LB

#23 Gandor OFFLINE  

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Posted Mon Feb 13, 2012 3:31 PM

LB,

Do you have a link to the updated instructions?

thank

#24 Prodos8 OFFLINE  

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Posted Tue Feb 14, 2012 6:55 AM

I did the FAQ mod on mine about five years ago and found it worked quite well using s-video on a tube tv. I did try and hook it up to a lcd projector and found it didn't look so good. I made a little adapter cable that goes from two male rca plugs to a female s-video so I could use a standard s-video cable since I couldn't find a s-video socket at the time. You can fudge composite by hooking the luma and chroma out into a rca y-connector and it works fairly well. Not nearly as sharp as s-video, however. The only real error I found with the FAQ mod was the chroma point was not correct, it was actually the next resistor over.

I guess if my tube tv that I use for my 5200/2600 ever dies, I'll look into one of these newer mods to work with a lcd/plasma tv.

#25 low_budget OFFLINE  

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Posted Wed Feb 15, 2012 11:43 AM

Progress! I received my v2.0 boards and am installing one now. I will take some screenshots of my results when finished. This board has mounting provisions for any components you might need in a complete s-video and composite mod circuit, so it will be great for experimentation.

I recently got two 4 port Atari 5200s on ebay and have noticed that the solder points on them are the same as 2 port Ataris. Also these 4 port systems have the same empty spot between the ANTIC and GTIA as the 2 port systems. So, I am guessing these are late model 4 port systems because they seem to have the 2600 adaptor supported.

I do not currently have my installation instructions online, I just include a paper copy with the boards. I have revised them so they cover early 4 port systems though. There are only a couple differences.

Also, I didn't mean to imply the original 5200 FAQ s-video guide was bad, it just has some errors. I did discover that it has the correct Chroma point, if its an early 4 port model. I also had good results using this mod on a CRT TV, it was when I tried it on a LCD flatscreen that I noticed it wasn't as good. Even though the solder points are labeled wrong, the schematic has the right resistor values to go with them so that's probably why nobody noticed. For as simple as it is, it works well.

Attached Thumbnails

  • 5200 s-video v2_0.JPG





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