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New 7800 S-Video Board available


Magic Knight

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Crossbow - Forgot to ask - have you at any stage adjusted or are looking at adjusting R56 and R57 pots on the 7800? I recall trimming these on one of my more 'knackered' pal units as they had poor colour until they were trimmed for best results.

 

I have already adjusted both of these knobs using the color bar generator to adjust the 2600 wheel, and Rev's utility to adjust the 7800 wheel. LCD flatpanels are notorious for producing odd colors on the 7800. I did forget to mention that these shots are ran through an HDMI upscaler. None of my flatpanels have native s-video input on them. So all my s-video systems run through a cheap monoprice Comp/S-vid to HDMI out upscaler. Let me get some shots taken from the PVM and see how that compares next. But I will tell you that I think some of the bleeding and ghosting could be minimized further with additional caps and or resistors before the video out on the chroma line perhaps? I'm not an engineer so I leave that stuff up to the experts. Also lets not forget that Magic is in PAL country and I'm in NTSC land and the colors will always be different in that regard.

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Too much green is the typical results on an HDTV, and the picture needs to be adjusted to lean "more red" on the display's tint/hue controls (Results provide a more red to green and less red to blue ratio).

Here's an example of the same console with Commando - great colors on a CRT and overly green on an HDTV:

post-18-0-05812900-1481995317_thumb.pngpost-18-0-73255700-1481995317_thumb.png

A good tell besides the game capture images is a palette capture chart. Per Tech Docs, Hue 1 (Color bar to the right of the Grayscale bar in the posted picture), should display as Gold-Golden. Such a setting provides shades of brown on the darker side of the luminescence scale, and shades of yellow on the lighter side. From the screen capture provided earlier, it looks more green-yellow on the light and a forest-green on the dark end of the scale.

 

The color wheel/pot on the 7800 is not a tint/hue control mechanism; instead, it adjusts the number of degrees separated between the hues.

 

When the pot is adjusted so there's a match shown in the 7800 Utility Cart capture or matching bar from the 7800 Diagnostic cart, it is spacing the degrees at ~25.7. Hues 1 and 15 are a (near identical) match. Total system colors though will be only 240.

 

Waiting a very long time to calibrate the console will result is an overall green Hue 14 and 15, during the first couple to several minutes, and then when finally warmed up, should reach a factory ~25.7 degree spacing, provisioning 240 colors.

 

Performing the calibration too soon, when the console warms up ends up with ~27.7 degrees between hues and Hue 14 and Hue 15 will wind up matching Hues 1 and 2 respectively. Total colors = 224.

 

Setting the color wheel pot calibration within the first couple of minutes (Not seconds, and not waiting several minutes), will assist Hue 15 to fall between Hue 1 and Hue 2 when the console warms up, spacing the hues ~26.7 degress, and it will reach it's full color palette of 256 colors.

 

A technical overview regarding color generation of the 7800 along with the consistency issues are covered excellently here, at the 7800.8bitdev.org site.

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Okay...just took some more pics from my PVM and also I changed the color option on my flatpanel to Warm and took some Commando shots again with that in place. My only issue with using the Warm setting is that while 7800 and other older games look good color wise, it causes too much red with my actual HD source content like the PS3, Wii U etc. Since everything goes into a single HD receiver, I'm able to have just one HDMI out cable to the flatpanel to minimize source changes to view what I want to play.

 

Here are some pics from the PVM. There is pattering from the CRT being picked up by the camera. I used a slower speed setting to eliminate the raster line, but this also makes the picture appear much brighter than it really is. Still about the best I can get from normal photos off my PVM up close. Also notice even on the PVM the colors appear to be a bit more green, but if you look at the colorbar, it is adjusted properly on the hue wheel.

 

post-6-0-03887900-1482004758_thumb.jpg post-6-0-29896200-1482004753_thumb.jpg post-6-0-19946600-1482004750_thumb.jpg post-6-0-23983100-1482004751_thumb.jpg

 

 

Here are pics of Commando with the flat panel set to the WARM color setting: Notice the color bleeding that is present, especially with the archway. But also notice that the "interference" patterns you see on the game play pic in the bricks etc... aren't seen in the detail shot I zoomed in on. Again, the interference isn't really there and is an artifact of my camera taking pics off the flat panel. The zoomed in shot is what I see with the colors and sharpness throughout. Only the color bleeding is actually there. Again, compared to the LHE mod this bleeding effect is reduced with Magic's solution.

 

post-6-0-24406400-1482004755_thumb.jpg post-6-0-26962000-1482004754_thumb.jpg post-6-0-19723100-1482004752_thumb.jpg

 

 

And finally here are pics of Magic Knight's S-Video board installed in my 7800. Note that I don't normally leave the output wires to the connectors to be so long, but I did this on purpose in case I need to change anything out again in the future (such as other video mods to test), plus it makes it much easier to work on the 7800 mainboard without having to cut anything as I would have to do otherwise. Notice that the pink audio input wire is actually soldered to the clipped north legs of the audio resistors and not the south end. This is opposite of what Magic's and the LHE instructions tell you to do. I found that on my 7800 if I attach the wires to the south attached legs, that the Pokey audio is very faint compared to the TIA. Also note that I included a detail shot of the additional 10uf capacitor I have going to the audio out to the RCA audio connectors.

 

post-6-0-19321500-1482004756_thumb.jpg post-6-0-18223900-1482004757_thumb.jpg post-6-0-93308700-1482004748_thumb.jpg

Edited by -^Cro§Bow^-
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Here are some pics from the PVM. There is pattering from the CRT being picked up by the camera. I used a slower speed setting to eliminate the raster line, but this also makes the picture appear much brighter than it really is. Still about the best I can get from normal photos off my PVM up close. Also notice even on the PVM the colors appear to be a bit more green, but if you look at the colorbar, it is adjusted properly on the hue wheel.

 

The color bar matches Hue 15 to Hue 1. It has no impact on how Hue 1 appears though. That is the issue from the capture... The colors highlighted here...

 

post-18-0-24220200-1482006072_thumb.png

 

...are not impacted at all by the color wheel/pot adjustment of the console.

 

Hue 1 colors are impacted strictly by the tint/hue setting of the display device. The color range for that section should be gold-golden; that is the intent of the Hue 1 color range. It provides shades of brown on the darker end (bottom-most swatches) and bright yellows (upper-most swatches) on the light end of the luminescence scale.

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Right...I get that. And adjusting my tv system for one console to look correct on its colors or more correct when I have up to 12 others also attached doesn't work for the rest when their colors are correct or at least appear to be correct to me. Going by the gold - golden aspect of Hue 1 column of colors, then the original standard color setting on my flatpanel appears to be the best match for that column of colors as was shown on the previous screenshots I attached. With that, Commando is certainly very green indeed LOL.

 

PVM - again the brightness isn't really this bright in actuality.

post-6-0-97033900-1482007341_thumb.jpg

 

Flat Panel - Hue 1 column appears to be more accurate here?

post-6-0-27970300-1482007343_thumb.png

 

Point being, if I adjust the reds...etc to make the 7800 look more correct on the flat panel, that will result in WAY too much red on everything else I play. Even in the warm setting, the white lettering on commando's opening is too beige and not pure white. So honestly there isn't really and adjustment I can make that is a happy medium with all. The PVM is adjusted with chroma about the 1:30 hour hand position on its knob. If I put it at the 12 oclock default setting, then everything I connect to it is dull, additionally this little PVM doesn't have adjustments for the colors separately. Just brightness, contrast, chroma, and volume. But it does have a dedicated s-video input and composite hence why I use it for bench work mostly.

Edited by -^Cro§Bow^-
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Flat Panel - Hue 1 column appears to be more accurate here?

post-18-0-25533000-1482026384_thumb.png

 

No. That is in the range of a Chartreuse hue (Greenish-Yellow/Yellowish-Green/Pear-like), and should be typically seen for Hue 14/E or 13/D. On a system in which the hues are separated by ~25.7 through ~26.7 degrees, that's exactly what is achieved. A Chartreuse range though contains too much green for the intent of Hue 1.

 

It should display more like what is seen here, the gold/golden range:

 

post-18-0-34871400-1482027183_thumb.jpg

 

Note the "Match Color" is a gold color, not leaning towards green.

 

Commando appears like this as a result:

 

post-18-0-20023400-1482027965_thumb.jpgpost-18-0-21425800-1482027967_thumb.jpg

 

I completely understand your points, and you need to setup and configure your display(s) for what works best for you and your preference overall. :)

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  • 2 months later...

Bringing this thread back up.

Is there any way to squeeze an hdmi upcomverter insode the 7800s shell plugged into this?

 

I use one of those $40 composite/s-video to HDMI out adapters. I'm sure if purchased one of those and took the guts out of the housing it came in, that you could likely squeeze everything into the 7800 somehow.

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Bringing this thread back up.

Is there any way to squeeze an hdmi upcomverter insode the 7800s shell plugged into this?

There's plenty of room as long as you remove the following:

 

1. Remove the hdmi upscaler plastic enclosure/box

 

2. Remove the 7800 shield (it's not like these days that your tv isn't shielded or Fcc care!

 

You can cover the upscaler pcb with a non conductive sleeve, so it doesn't short circuit.

 

You can also link the psu power to the input of the upscaler so it's all powered simultaneously.

 

I've done it a couple of times and works great. No lag was apparent despite there being a nano second or two (apparently).

 

I would add a dedicated reset switch for the Atari only as hdmis tend to take longer to reboot than the Atari which is a pain when swopping carts. This can discretely done at the left or right of the case or if clever - by bi-passing the on board one for your sneeky/cheeky hack version.

Edited by Magic Knight
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  • 1 year later...

Hey all,

 

Ive got some new S-Video boards made. As theres been an upsurge of requests in the last few months, ive done a couple of batches.

 

This is version 2 and all units are fully tested on 7800 and 2600 models.

 

I also offer this in kit form (if your feeling confident!) This is of course cheaper than an assembled and tested unit.

 

 

post-34640-0-86762900-1542032950.jpgpost-34640-0-94905300-1542033045.jpg

 

post-34640-0-52496200-1542034246.jpg

 

If your interested, then the details are as follows:

 

Assembled:

1 x MK S-Video board

1 x S-Video 4 pin socket

1 x Audio Socket

Lead wires (assmebled and for linkage)

PDF instructions set by email.

 

Price: £25 UKP

 

Kit form (only available direct) - choice of colors (whilst in stock)

1 x MK S-Video board (red, blue or yellow)

1 x Component set

1 x S-Video 4 pin Socket

1 x Audio Socket

Lead wires (assembled and for linkage)

PDF instructions set by email.

PDF Component list and layout

 

Price: £16 UKP

 

Postage costs are follows:

 

UK - First Class - £2

UK - Recorded - £3

 

EUR - Airmail - £4.50 UKP

EUR - Airmail recorded - £9.50

 

 

Outside Europe - Airmail - £6 UKP

Outside Europe - Recorded - £11 UKP

 

Postage is for any quantity when ordered direct (little or as many as you require in either build)

 

 

You can buy these direct -(PM me for payment details)

 

alternatively - ive listed them on Ebay (slightly more expensive and postage structure to cover listing costs).

 

 

Due to the fickle way they are now listed for home and overseas - ive listed the Assembled versions only separately for convenience.

 

 

UK and Europe - https://www.ebay.co.uk/itm/123485311494?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

Outside Europe - https://www.ebay.com/itm/Atari-7800-S-video-graphics-board-Easy-install-with-instructions-for-PAL-NTS/123485311494?hash=item1cc04c5206:g:j1YAAOSwT2Bb6WMm:rk:2:pf:1

 

 

 

 

Let me know if you have any questions :0)

 

Regards

 

Magic Knight

Edited by Magic Knight
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Awesome!!!

 

What the pot on the board do? Same as before adjusting the luma? Also how are you handling the audio on this board exactly?

 

I will let a few people know that have been on my waiting list for this. I still wish you had included outputs for composite as well because I get a lot of requests for that too. But s-video is better than nothing!

 

Also I still wish you offered an s-video jack that has a nut on it to lock it in. The one you provide is essentially glue to epoxy only. Still...

 

Thanks for the update!

Edited by -^Cro§Bow^-
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Awesome!!!

 

What the pot on the board do? Same as before adjusting the luma? Also how are you handling the audio on this board exactly?

 

I will let a few people know that have been on my waiting list for this. I still wish you had included outputs for composite as well because I get a lot of requests for that too. But s-video is better than nothing!

 

Also I still wish you offered an s-video jack that has a nut on it to lock it in. The one you provide is essentially glue to epoxy only. Still...

 

Thanks for the update!

 

Hi Crossbow,

 

The pot adjusts the amplification when the 4 luma signal hit this part of the circuit together, it helps on different tv/monitors (being all different makes and models and results) . The richness of the picture is affected so its kinda adjusted to taste also.

 

Audio is filtered/smoothed via separate resistor/cap combo from both sound sources rather than hardwired direct to IC (TIA and external sources - (ie the pokey on supported carts)

 

I did consider a Composite output, but thought it might be expensive for having a lower quality feed where a simpler circuit can handle composite. I havent tried it yet, but in theory twisting luma/chroma togerther may be just that simple. Ill try that shortly as it will be useful to know.

Ive a standard composite type circuit also, so i might compare results as i reckon the signal conditioning on this board off the IC's being conditioned (and then subsequently simply downrated) at the output would be better than the usual 2k/3k amplifier method. .

 

The socket is just my preference. The idea of a neat hole and epoxy over 3 holes and a larger footprint is more neater for me. However choice being a good thing - looking but the one you mentioned is easily sought locally in the world and would probably be stronger longer term.

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How well do things like this work for composite when only s-video is available?

 

https://www.amazon.com/dp/B0000BZ2WC

 

That device on amazon would just twist luma and chroma together to make composite. im going to be trying this on my board to see what results i get. ill get back on that tomorrow.

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  • 2 weeks later...

Hey all,

 

Ive got some new S-Video boards made. As theres been an upsurge of requests in the last few months, ive done a couple of batches.

 

This is version 2 and all units are fully tested on 7800 and 2600 models.

 

I also offer this in kit form (if your feeling confident!) This is of course cheaper than an assembled and tested unit.

 

 

attachicon.gifpcb ebay-mini.jpgattachicon.gifpcb batch ebay-mini.jpg

 

attachicon.gifcolours-a.jpg

 

If your interested, then the details are as follows:

 

Assembled:

1 x MK S-Video board

1 x S-Video 4 pin socket

1 x Audio Socket

Lead wires (assmebled and for linkage)

PDF instructions set by email.

 

Price: £25 UKP

 

Kit form (only available direct) - choice of colors (whilst in stock)

1 x MK S-Video board (red, blue or yellow)

1 x Component set

1 x S-Video 4 pin Socket

1 x Audio Socket

Lead wires (assembled and for linkage)

PDF instructions set by email.

PDF Component list and layout

 

Price: £16 UKP

 

Postage costs are follows:

 

UK - First Class - £2

UK - Recorded - £3

 

EUR - Airmail - £4.50 UKP

EUR - Airmail recorded - £9.50

 

 

Outside Europe - Airmail - £6 UKP

Outside Europe - Recorded - £11 UKP

 

Postage is for any quantity when ordered direct (little or as many as you require in either build)

 

 

You can buy these direct -(PM me for payment details)

 

alternatively - ive listed them on Ebay (slightly more expensive and postage structure to cover listing costs).

 

 

Due to the fickle way they are now listed for home and overseas - ive listed the Assembled versions only separately for convenience.

 

 

UK and Europe - https://www.ebay.co.uk/itm/123485311494?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

Outside Europe - https://www.ebay.com/itm/Atari-7800-S-video-graphics-board-Easy-install-with-instructions-for-PAL-NTS/123485311494?hash=item1cc04c5206:g:j1YAAOSwT2Bb6WMm:rk:2:pf:1

 

 

 

 

Let me know if you have any questions :0)

 

Regards

 

Magic Knight

Are these sold out already? Asking as I noticed the ebay links weren't active any longer..

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Ive ditched ebay as there was no interest on this by randoms (ie non users of this user group) - instead 100% of the interest is on here.

 

Users have PM'd me here for ordering either kit or pre-made boards. In addition - im now under taking installations on request as im getting asked for that also :0)

 

 

Looking forward - Im thinking of releasing here on the forum - the design files and install manual etc here for guys to make their own and/or evolve this design - as i feel i want to put something into the community in the development sense. Most others have done this and it shouldn't really be seen as a big secret design or anything.

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That device on amazon would just twist luma and chroma together to make composite. im going to be trying this on my board to see what results i get. ill get back on that tomorrow.

Did you by change test this out yet? Curious to the results...

 

BTW...sending you a PM...thanks!

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Awesome! If you've still got these in stock on Dec 7, I'll definitely be ordering a kit (in any color except white or black if possible). Gotta wait 'til then to get past the pain of the new TV we just bought last week. icon_smile.gif

What do you have against white and black? LOL I actually ordered up two of the black board kits and a spare red pcb in my order just to have on hand.

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