SCART/VGA/S-Video A/V mod interest check

[GroovyBee]

I've thought about an Inty A/V mod for a while and I hear both good and bad reports about the video quality of the existing A/V mods so I thought I'd throw it open to others for their input and a discussion.

 

Looking at the way the STIC (Inty graphics chip) generates signals for the final video stage I can see three ways of getting different methods of A/V out of it as follows :-

 

1) RGB SCART.

2) S-Video for PAL and/or NTSC.

3) VGA at 640x480.

 

There would be stereo audio out for all display methods but it'd be 2 channels of mono because Inty games have no concept of left/right audio.

 

The options listed above are listed in terms of complexity and also rising cost with RGB SCART being the cheapest and VGA the most expensive.

 

Ideally installation would be done in the following steps (after opening up the console) :-

 

- Remove the glue holding the STIC down.

- Remove the STIC (its is a socket in my Inty I and looks to be socketed on other versions as well)

- Plug the new A/V PCB into the STIC's socket.

- Plug the original STIC into a socket on the new PCB.

- Solder audio wire(s).

 

However, if there is no space to install the mod like that (it looks just about possible) then its 10 wires to solder (at a guess) or you'll need to remove the heat sink from the STIC (not sure how hot that chip gets or how easy that is to remove either).

 

Until I sit down and design the circuit(s) I've no idea on the final price for any of the 3 candidates.

 

I've created a poll at the top to see what the interest levels are in each design. If you have any other thoughts let me know.

[+grips03]

Many newer TVs in the US are dropping S-video, also RGB / VGA have better clarity. Either RGB or VGA would be fine.

RGB is nice as ebay has cheap RGB to component video converters.

VGA plugs into most modern TVs, but takes more to convert to another format.

 

It would be great to have a new video mod

[Uzumaki]

I'm for it as well but it seems SCART is winning. SCART isn't used in USA and it's rare to find a TV or monitor with SCART support. Eh, SCART to Component or VGA exists. For some reason SCART to Component is around $50 while to VGA is around $5 each.

[GroovyBee]

Don't worry about who is winning at the moment. Its just an interest check to see what people would like.

[+SoulBuster]

A VGA mod would allow using a non-television monitor to be used with it, would it not? Direct plug and play? So any cheap monitor would work?

[Uzumaki]

If it's a standard VGA, yes. A nice 15" 4:3 VGA would look razor sharp compared to RF on any TV

[GroovyBee]

I have almost finished the design of the RGB SCART and S-Video PAL options (both will be on the same PCB). I need to look at the digital and analogue video signals on the Inty's motherboard PCB to see if there are any "gotchas" and also take physical measurements of the space available around the STIC before finalising the schematic and laying out a PCB.

 

Its interesting to see the VGA option doing so well in the poll. It would be standard 640x480 @ 60Hz VGA when used in an NTSC machine (for PAL machines, VGA would be at 50Hz and so it would need a multi-sync monitor). If that design went into production it'd probably ship with a cart that would allow you to adjust the built in palette colours yourself and save them to on-board EEPROM. However, I haven't put much thought into the design of it yet.

[+grips03]

I'm glad to hear about this. I've yet to video mod the Intv2. RGB or VGA would a major improvement.

[Uzumaki]

I checked Inty 2 I have, 8900 is socketed with no heat sink or glue so it should be easy to swap it. However it is socketed near the power daugherboard so depending on orientation and shape, it might not fit. Also there is less than 1/2 inch of space between top of the socketed chip and bottom of the top case shell. zyjiock board would present problems.I can take picture of it if you needed it. TWO good thing about Inty 2: no dumb welded on RF shield and no huge heat sink either.

 

"Fat" Intellivision has RF shield that is welded on so taking it off would be slow and tedious if you don't have strong enough iron, the whole shield is one big heat sink and a low watt iron won't be enough. Since Inty 2 doesn't use heat sink, it seems likely those aren't needed on "fat" models either.

Edited April 30, 2013 by Uzumaki

[GroovyBee]

The PAL Intys I've looked at don't have an RF shield so that isn't much of an issue on this side of the pond. There also seem to be a couple of PAL Inty PCB revisions with differing video generation circuitry.

 

I have an Inty II on the way but high resolution images of the Inty II motherboard that are up close and in focus would be good. If you can take 2 of them with a ruler in the X and Y orientation of the board that'd be even better.

 

The height restriction isn't really an issue because the new PCB will use surface mount components.

[GroovyBee]

The SCART/S-Video design is pretty much done for both PAL and NTSC. I need to prod and poke the Inty hardware to make sure that nothing else needs to be added to the PCB. Hopefully, I'll get some time to do that tomorrow. I haven't priced the design up yet but with the number of components (currently just over 100 - but it depends what variant is built) its not going to be anywhere near the typical Atari AV mods in price.

[HARMIK]

I voted S-Video all I can say is Thank You GroovyBee I have been wanting something high quality like this for a long time. Plan on hooking up to Sony CRT TVs.

[+grips03]

The SCART/S-Video design is pretty much done for both PAL and NTSC. I need to prod and poke the Inty hardware to make sure that nothing else needs to be added to the PCB. Hopefully, I'll get some time to do that tomorrow. I haven't priced the design up yet but with the number of components (currently just over 100 - but it depends what variant is built) its not going to be anywhere near the typical Atari AV mods in price.

 

Does the mod have RGB SCART or S-Video SCART or both?

[Uzumaki]

 

I have an Inty II on the way but high resolution images of the Inty II motherboard that are up close and in focus would be good. If you can take 2 of them with a ruler in the X and Y orientation of the board that'd be even better.

 

 

Taken at max resolution with my decent camera. It could be better but I misplaced my tripod and my really good camera is tricky to get close up without steady hand or tripod.

A bit over 4MB each:

http://personalpages.tds.net/~wilykat/IMG_8727.JPG

http://personalpages.tds.net/~wilykat/IMG_8728.JPG

 

3 chips are socketed on Inty 2 board, the one in the middle right next to power daughterboard connector is the 8900 chip that you are looking to make a plug-in upgrade.

 

Even though you are making the board with SMD, you still need to add a socket and plug the original chip back in. From the top of the socketed chips there is a bit less than 1/2 inch clearance to bottom of the shell so the board + socket + 8900 chip can't be too tall. And it can't be too short either maybe add 1 mm from top of the socket to ensure it clears the neighboring non-socketed chips. About 1" from 8900 toward the back is the 7.1-whatever MHz oscilator that drives the system. You also have about 1/4" margin on either side before the board would hit the power daughterboard or the 2 socketed chips. There is room toward the front of the system.

 

I don't know how Inty 1 is laid out but hopefully you could make one board that fits a majority of both "fat" and 2.

 

I did notice another possible issue with adding video to Inty 2: not much room to add a video out port. Adding them to the side by the cart port is one way but it'd prevent the use of ECS or System Changer. (System Changer won't work with your upgrade board since it's direct to RF modulator and doesn't use 8900 at all) Desoldering and removing the stock RF box would work but a simple mod would be needed to provide power on video pin, the "fat" inty has a diode from Vcc source to video that is not present on Inty 2.

[GroovyBee]

Does the mod have RGB SCART or S-Video SCART or both?

 

Its one or the other. If you want RGB SCART you don't need the extra parts that give you S-Video so they won't be fitted to a SCART PCB. Currently there will be 3 connector headers on the PCB. One for S-Video (and composite), one for RGB SCART and one for audio. The "kit" will also be supplied with a cable that connects the PCB to the outside world. I'm trying to keep it as "plug and play" as possible so soldering will be kept to a minimum.

[GroovyBee]

Taken at max resolution with my decent camera.

 

Thanks for the images and extra info. The images will come in handy later on when I lay out the PCB.

[GroovyBee]

I voted S-Video all I can say is Thank You GroovyBee I have been wanting something high quality like this for a long time. Plan on hooking up to Sony CRT TVs.

 

No worries. Its an interesting project going from purely digital signals to a standard video signal. I'm looking forward to seeing the difference in video quality compared to stock RF too.

[ApolloBoy]

Damn, this almost makes me want to pick up an INTV again! I voted for both RGB and S-video but I would be fine with just RGB.

[+grips03]

the number of components (currently just over 100 - but it depends what variant is built)

 

That's a lot of parts.

 

Do you have before and after pics, i.e. RF, composite, s-video, and RGB?

 

For other consoles I use RGB and its definitely worth it.

[GroovyBee]

That's a lot of parts.

 

Components soon add up when you start decoupling devices and terminating signals correctly. Plus there are some contingency parts on there "just in case". Don't forget its creating the video signal from a purely digital source using modern components so you aren't tweaking what is already there like many other machine's AV mods.

 

Do you have before and after pics, i.e. RF, composite, s-video, and RGB?

 

I'll be doing before and after TV shots when the PCB comes in and its been built up and tested. I thought about hand making a prototype using pin through hole components but I think there will be issues introduced that won't be there in the final version due to the nature of perf/vero board construction e.g. excessive parasitic capacitance, poor/no GND plane, crosstalk and so on.

 

Anyways... While I'm waiting for the PCB to come in I can get on with the VHDL code it needs.

[pimpmaul69]

Components soon add up when you start decoupling devices and terminating signals correctly. Plus there are some contingency parts on there "just in case". Don't forget its creating the video signal from a purely digital source using modern components so you aren't tweaking what is already there like many other machine's AV mods.

this is called doing a job right. the only av mod i felt was really good while being the simplest of them all was the coleco av mod. atari 2600 never looked as good on any retro system as on a modded coleco. coleco games looked great too. as far as "rf" goes i feel the coleco and intv are the among best quality systems. even the xbox1 looked horrible on rf until the 1.6 boards (last version made) Edited May 1, 2013 by pimpmaul69

[+grips03]

this is called doing a job right. the only av mod i felt was really good while being the simplest of them all was the coleco av mod. atari 2600 never looked as good on any retro system as on a modded coleco. coleco games looked great too. as far as "rf" goes i feel the coleco and intv are the among best quality systems. even the xbox1 looked horrible on rf until the 1.6 boards (last version made)

Not sure if your taking about Matt's F18A Coleco VGA board, but that one is awesome.

 

GB - This Intv board sounds so awesome, I hope it fits Intv2. Worth it at any price. thanks so much for making this!

[GroovyBee]

GB - This Intv board sounds so awesome, I hope it fits Intv2. Worth it at any price. thanks so much for making this!

 

Its been on my list of things to do for a long time. The RF on my Intys is really bad so they aren't much fun to develop homebrew games on.

 

I'm hoping the same PCB will fit both Inty I and II. PAL Intys don't have the RF shield so hopefully its removal on an NTSC Inty I machine won't impact the signal quality.

[pimpmaul69]

Not sure if your taking about Matt's F18A Coleco VGA board, but that one is awesome.

 

GB - This Intv board sounds so awesome, I hope it fits Intv2. Worth it at any price. thanks so much for making this!

i was just talking about the composite mod with a transistor. looks perfect on my lcd

Its been on my list of things to do for a long time. The RF on my Intys is really bad so they aren't much fun to develop homebrew games on.

 

I'm hoping the same PCB will fit both Inty I and II. PAL Intys don't have the RF shield so hopefully its removal on an NTSC Inty I machine won't impact the signal quality.

i have never noticed any interferance working on them. then again i dont use my microwave often enough to test. also a shame the rf quality is not good an a pal machine. or at least yours anyways. Edited May 2, 2013 by pimpmaul69

[bikeguychicago]

Groovy,

 

Should the mods become available, would you offer an installation service? I have no EE training and wouldn't be willing to crack open one of my Intv units for fear I would break it.

 

Thanks!