Quick & Easy Video Upgrade for 800XL

[+bob1200xl]

GTIA outputs two types of video signal - 4 bit LUMA and phase encoded (digital) CHROMA. All the color indirection, sprites and such are already done by the stock GTIA - we have digital values that become s-video, composite, or RF. The CHROMA is just a signal that changes level at a certain time in the cycle, in 16 discrete steps. (well, actually 'black and white' kills the phase transistion entirely) The problems with converting the video at this point are minimal and discrete.

 

Bob

 

 

I was just looking into this RGB business and realized that producing the RGB output "at source" would require interception of display data at the point ANTIC deals with it, requiring emulation of GTIA a la VBXE. If we tap the video signal off GTIA it's going to be a degraded s-video to RGB conversion.

 

Genuine RGB output is one of VBXE's greatest selling points. No wonder the idea of a "cut down" version didn't appeal much: all the GTIA emulation would still be required, even if the custom graphics modes were jettisonned.

[flashjazzcat]

Thanks Bob. I have a friend who's interested in designing this circuit. He has a dual beam scope but knows little about the Atari hardware... unfortunately I'm the conduit between him and this topic.

[rchennau]

Just a quick question???? have you tried running just the Luma signal without any chroma to see if the Jaggies are still there. [black / White] screen only??

Absolutely. I fired up the 800XL before even hooking up the chroma and the jaggies were pronounced. I've progressively applied the Super Video 2.1XL mod, studying the results after adding and changing components. Quality is certainly improved - and the jaggies aren't as bad - although most of the modifications seem to address signal strength and colour saturation.

 

 

It's hard to photograph the screen well, and while the above picture doesn't look too bad, 80 column text doesn't look great and curiously there's quite a lot of artifacting still in evidence. Funnily enough, the most comfortable compromise between sharpness and smoothness is obtained by running the composite video into the back of the TV at the same time. This results in a mixed image (s-video and composite), as seen below:

 

 

I've just hooked up another stock 65XE and the picture knocks spots off the XL: it's almost approaching VBXE quality.

 

I have a similar problem and am not sure if it is my amateur hour soldering skills or just hooking the S-VIDEO up to a high definition monitor. I have vertical bands (not jagged at least).

 

Three pictures included.

The first is a screencap taken on my computer via an S-VIDEO capture card.

The second and third are via my iPhone while running S-VIDEO to a Toshiba TV with max resolution of 1080i although of course it S-Video will be 480i.

Edited July 5, 2010 by rchennau

[flashjazzcat]

My 800XL was the same until I disconnected the RF modulator and otherwise severed the composite video circuit. See my "UltraVideo XL" mod on my website (it's basically SuperVideo with a couple of amendments/additions, and has "caveat emptor" written all over it). It's clear from the post you quote that I was speaking a few days before getting drastic with the 800XL.

[WIZZARD77]

I performed the mod this weekend and I was getting the zigzag line noise mentioned earlier. I then pulled the 4 wires from the RF modulator to the board and it cleared up. I now have a light rolling ghosting in the background. It displays perfectly clear for about 1-2 minutes then the interference shows. My 130xe shows the same interference but it is much lighter. Do I need more shielding somewhere or is it just the nature of the beast.

[Rybags]

I think it might be "nature of the beast".

 

I wonder how an XE would go if you were to just supply the entire video circuit with a totally seperate power source once it's left GTIA (or, the luma part at least).

Edited July 12, 2010 by Rybags

[flashjazzcat]

I think it might be "nature of the beast".

 

I wonder how an XE would go if you were to just supply the entire video circuit with a totally seperate power source once it's left GTIA (or, the luma part at least).

Time to get the soldering iron out.

[+bob1200xl]

You might be OK if you run the digital LUMA/SYNC bits and the digital CHROMA bit right from the output of GTIA through a schmitt opto-isolator before you generate video on a nice 4-layer PCB.

 

If you don't drop out the noise on ground, you're stuck with video birdies. Makes no matter if the signal pin is rock-solid and your ground bounces around - it's the difference between them that is displayed.

 

Bob

 

 

I think it might be "nature of the beast".

 

I wonder how an XE would go if you were to just supply the entire video circuit with a totally seperate power source once it's left GTIA (or, the luma part at least).

[rchennau]

Just a quick question???? have you tried running just the Luma signal without any chroma to see if the Jaggies are still there. [black / White] screen only??

Absolutely. I fired up the 800XL before even hooking up the chroma and the jaggies were pronounced. I've progressively applied the Super Video 2.1XL mod, studying the results after adding and changing components. Quality is certainly improved - and the jaggies aren't as bad - although most of the modifications seem to address signal strength and colour saturation.

 

 

It's hard to photograph the screen well, and while the above picture doesn't look too bad, 80 column text doesn't look great and curiously there's quite a lot of artifacting still in evidence. Funnily enough, the most comfortable compromise between sharpness and smoothness is obtained by running the composite video into the back of the TV at the same time. This results in a mixed image (s-video and composite), as seen below:

 

 

I've just hooked up another stock 65XE and the picture knocks spots off the XL: it's almost approaching VBXE quality.

 

I have a similar problem and am not sure if it is my amateur hour soldering skills or just hooking the S-VIDEO up to a high definition monitor. I have vertical bands (not jagged at least).

 

Three pictures included.

The first is a screencap taken on my computer via an S-VIDEO capture card.

The second and third are via my iPhone while running S-VIDEO to a Toshiba TV with max resolution of 1080i although of course it S-Video will be 480i.

 

I ripped out the Quick & Easy Video Upgrade and replaced with the Super Video 2.1 upgrade. I have to say that the difference between the two is noticeable. The composite video disable switch really makes a difference as it turns off some of the noise of the composite signal. One step I have not completed is replacing R52 with a 2.7K OHM resistor. I only have a 3.2K. I know nothing of the effect adding a higher value resistor would have.

 

 

I'm also thinking of trying the UltraVideo upgrade but do not like the idea of removing the RF.

[flashjazzcat]

I'm also thinking of trying the UltraVideo upgrade but do not like the idea of removing the RF.

There are purportedly advantages to removing that huge hunk of metal but if you're enjoying good results with the composite disconnected, I wouldn't fret too much about the RF box.

Edited July 14, 2010 by flashjazzcat

[+remowilliams]

I've done a bunch of video upgrades on different models, but never did anything with my original stock 800XL that I bought new back in the day and was my primary computer. After receiving my RAM 320XL today (which is simply amazing), I pulled my old friend from out of storage and was surprised to find it did not have a chroma line connected. So I figured while I was doing that and adding the +5V to PBI, I'd do this upgrade. The results were stunning compared to the stock video

 

I normally don't go showing pictures of anything I've soldered (to avoid scaring people ) but I figured I'd post this here just in case it might be of use to someone.

 

[+Larry]

I'd never done the Q&E video upgrade before, but just applied it to a stock 800XL, and the results are great -- arguably every bit as good as the much more labor intensive Super Video 2.1. Great color saturation and luminance -- really, really nice.

-Larry

[+Larry]

Since a picture is worth...

 

The color is deep and intense; the luminance is great, but not overpowering (to my eyes, at least). Vertical timing lines are very, very faint, and not troublesome.

 

This is the mod!

 

-Larry

QE Video on 800XL.bmp

[STeSearcher]

Would the directions for this mod be the same for the 1200XL as the 800XL?

[+bob1200xl]

No - the circuits are different.

 

Bob

 

 

Would the directions for this mod be the same for the 1200XL as the 800XL?

[+wood_jl]

Happy New Year, everybody.

 

What about NO RESISTOR IN CHROMA?

 

Tonight, I engaged in hamfisted, amateur soldering, so I took out my Walmart equipment and hooked up the chroma line on my Rev.C 800XL. I didn't use a resistor, simply because I did not have one, so I decided to see what it looks like. I have not done any other changes yet.

 

The colors look kind of dull - the screen is not as bright as the 130XE - the blue screen just seems a little dull. I don't know if I should call it "washed out" or what. In other regards, the definition is equally sharp, and I see no zigzags, and I don't see vertical lines.

 

I bought a pack of resistors:

 

 

And put one in-line. This fixed the dull colors! The leads on these resistors seem thick. Not an issue for this, but are they available with different gauge leads? How is this specified?

 

Thanks for the advice. This is really simple stuff to some, something new to others. I appreciate the helpful suggestions from bob1200xl, metalguy66, Bryan, and others. Such low-level of ability/experience may be seen as retarded, so I appreciate your patience and helpfulness. Now I'm wondering about the "quick and easy" mod, since this thing - while scads better than composite - still lacks the panache of a stock XE output. Such a mod will be a handful for someone at my level, but even at this level, it's pretty satisfying seeing S-video, even if it's stock!

[BillC]

The resistors you used are 1/2 watt, lower power rated resistors(1/4 or 1/8 watt) will be smaller and have smaller leads.

 

You have to be careful not to use a resistor with too low a power rating for the application, but that isn't a concern in this case.

 

Bill

 

I bought a pack of resistors:

 

 

And put one in-line. This fixed the dull colors! The leads on these resistors seem thick. Not an issue for this, but are they available with different gauge leads? How is this specified?

 

Thanks for the advice. This is really simple stuff to some, something new to others. I appreciate the helpful suggestions from bob1200xl, metalguy66, Bryan, and others. Such low-level of ability/experience may be seen as retarded, so I appreciate your patience and helpfulness. Now I'm wondering about the "quick and easy" mod, since this thing - while scads better than composite - still lacks the panache of a stock XE output. Such a mod will be a handful for someone at my level, but even at this level, it's pretty satisfying seeing S-video, even if it's stock!

[JohnBuell]

ARGH. I knew there was a reason I shouldn't be let around soldering irons. And the huge 2nd degree burn across my left knuckles proves it. I just tried this whole thing (as seen in post #1) this afternoon, having ordered 40/60 solder, the resistors, and wire from RadioShack.com. I started with a stock 800XL (not my original, one I got in an auction deal). Now I have an 800XL that outputs sound, and nothing else. I have everything connected, I just don't know if something got short-circuited or WTF happened. That'll teach me not to do one at a time.

 

EDIT (to add): Going back through the photos, everything _looks_ ok - I took out C56 and L5, did a wire from the front of L5 to the front of C3, did the other resistors - the only thing I can think of is, do the directions of the resistors matter? It's been too long since I've played with electronics diagrams to try to remember.... Still only get sound though, dang it!

Edited April 3, 2011 by JohnBuell

[JohnBuell]

And adding here, for the sake of reference, that the 800XL I'm playing with is an NTSC Rev A2 board.

[mimo]

Resistors are an anyway up component. Can you photo the soldering you have done, maybe someone can spot something

[JohnBuell]

Resistors are an anyway up component. Can you photo the soldering you have done, maybe someone can spot something

 

Sure, crappy though it is? I'll have to wrangle the camera back from the wife.

[JohnBuell]

Here we go. I did the best I could with the Macro function on my Olympus camera, and resized these in Picasa.

[+orpheuswaking]

I keep saying I'm going to do this to my XL's (all 11 of them) but I never seem to get around to it.

[Rachel-Emma]

The one I'm considering replacing it with is the Onkyo TX-SR608.

 

You really need an Onkyo NR808

[bobkat2769]

The one I'm considering replacing it with is the Onkyo TX-SR608.

 

You really need an Onkyo NR808

Eeeeepppp!

 

That's way out of my price range! =o.O=;;

 

Not that anyone probably cares, but since you seem interested... =^.^=

 

I'm actually considering the TX-SR707. It's THX certified, and has plenty of S-video and HDMI inputs. And it's a lot more affordable.

 

For now I'm just using a cheap HDMI auto-switch for the two disc players and that's working out just fine. =^.^=

 

But whichever one I do upgrade to it might not matter too much. I recently found a device that converts both S-video and component to HDMI for about $42. I don't know how good it is though as I haven't tried it yet. If anyone here is interested in the video converter let me know and I'll post the info about it.

 

I'd been hoping that someone here would come up with a way to cheaply mod an 800XL to output component video, but I guess it's either too difficult or nobody wants to bother with it. Considering that S-video inputs seem to be going the way of the dodo I'd think that someone beside me would be interested in this.

 

 

BobKat