Preparing for Super Video 2.1 in 1200XL

[Smokeless Joe]

I just got my very first 1200XL and I'm afraid to say the video looks like dog crap. So I've decided to install the Super Video 2.1 mod.

 

The instructions I've found include what looks like a scan from the original articles:

 

http://atarionline.pl/biblioteka/materialy_ksiazkowe/SuperVideo%2021XL%20oraz%20errata.pdf

and the very nice transcription/update on Clarence Dyson's page:

http://www.wolfpup.net/atarimods/supervid5.html

 

[Wolfpup.net has been offline for a while so I'm looking at a cached copy. I hope it comes back.]

 

I've poured over the instructions and have a couple questions, either for anyone who's done the mod or 1200XL experts in general:

 

1. Three places suggest putting resistors in parallel:

- Step 4 at R44 (two 150 ohm resistors for 75 ohms total)

- Step 5 at R23 (120 ohm added to stock 180 ohm resistor for 72 ohms total)

- Step 9 at R45 (330 ohm added to stock 100 ohm resistor for 76.74 ohms total)

 

Is there any problem with using single 75 ohm resistors in these places? Has anyone tried that? Did they not make 75 ohm resistors back in 1993?

 

2. How important is it to install the composite video enable/disable switch in steps 7 and 8? I'm planning to use S-video as my connection, so could I just remove R24 and call it good?

 

Any other advice for installing SV2.1 in a 1200XL would be greatly appreciated.

 

Thanks!

 

- Joe

Edited April 20, 2014 by Smokeless Joe

[Caterpiggle]

Please contact to Bob Woolley. He will guide you from there with video issue.

[+bob1200xl]

You might try just replacing C115, L15 and R63 (up by the SIO socket) with wire or 1 ohm resistors (looks better than bare wire)

 

For s-video, use the LUMA and COMPOSITE signals, rather than LUMA and CHROMA. This looks pretty good and is a lot easier than the SV2.1.

 

Yes, they made 75 ohm resistors way before 1993. They were just less common because they are 5% tolerance, where 100, 150 and 180 ohms are 10% values.

 

Bob

[ACML]

You might try just replacing C115, L15 and R63 (up by the SIO socket) with wire or 1 ohm resistors (looks better than bare wire)

 

For s-video, use the LUMA and COMPOSITE signals, rather than LUMA and CHROMA. This looks pretty good and is a lot easier than the SV2.1.

 

Yes, they made 75 ohm resistors way before 1993. They were just less common because they are 5% tolerance, where 100, 150 and 180 ohms are 10% values.

 

Bob

I've done the ClearPic 2 and the C115, L15 and R63 described above. The short option (C115, L15) does improve the video significantly. I just jumped the composite line at the monitor jack to the Chorma pin for Svideo. It is good, but when using Omniview80 (80 column), there is still bleed (possible artifacting). The ClearPic 2 is superior in every way. Extremely clear sharp video, but you will the RF NTSC channel 3-4 output. That's actually a plus, because I use the channel selector as an OS selector using the XL OS and the Onmiview80 OS on two 27128s. The Omniview80 OS is based on the 400/800 OSB ROM and is 99.5 compatible with old OSB software. Plus it allows 64K games to run using the OSB OS. The 800XL OS still retains all the 1200XL key functions and L1 & L2 LED functions.

[Smokeless Joe]

I tried jumping C115, L15 and R63 with 1 ohm resistors (plus chroma from R44) and I thought it looked even worse; the color was washed out and the screen had all sorts of wavy lines horizontal, vertical AND diagonal.

 

The resistors were Radio Shack bulk resistors that rated at 1.4 ohms on my multimeter. 5% tolerance my ass.

 

I'm beginning to suspect my monitor is no good for this job. I have a Sony MFM-HT95 LCD TV/monitor and even the quickie 800XL video mod (remove C56, lift right side of C54, chroma from R67/R68) looks jumpy and squiggly on screen.

 

My cable might be screwy too. I first did the quickie 800XL video mod on a spare motherboard with a broken monitor plug, so I just soldered the s-video cable directly to the motherboard. That looked better than the s-video cable I got from 8bitclassics.com.

 

When you use composite for chroma, are you making your own s-video plug or do you short pin 4 to pin 5 on the monitor plug?

Edited April 20, 2014 by Smokeless Joe

[Smokeless Joe]

I just jumped the composite line at the monitor jack to the Chorma pin for Svideo.

 

I just saw this answer after I posted my question. I'll try this and see if it helps.

[+bob1200xl]

The older s-video monitors used RCA jacks for LUMA, CHROMA, and COMPOSITE inputs. That's what I use on my Teknika MJ-22. For the newer s-video jacks, I made a simple box. Notice that LUMA is terminated with 75 ohms.

 

Bob

 

 

[+bob1200xl]

CHROMA from R44?

 

Use COMPOSITE.

 

Bob

[flashjazzcat]

Some pics I took when doing ClearPic 2002 on a 1200XL the other day. I'd forgotten what a drastic improvement it is (see the "before and after" photo):

 

 

 

 

Pics are of s-video (NTSC) through an LG M227WD 22" LCD TV/Monitor (none of my CRTs will handle NTSC colour).

[ACML]

I do the ClearPic 2002 on all 1200XLs. You can order small quantities of resistors and caps at Digi-Key. I buy my s-video cables from Cory at 8-Classics. A must if you want 80 column text that you can read. I think a ClearPic 2002 1200XL has better video than even a stock 800. S-video that is, the composite does not change much.

[flashjazzcat]

Does artifacting still work through composite, or does ClearPic eliminate it? Both 1200XLs sitting here have ClearPic, but one's PAL and I have no composite cable anyway (only s-video).

[ACML]

Does artifacting still work through composite, or does ClearPic eliminate it? Both 1200XLs sitting here have ClearPic, but one's PAL and I have no composite cable anyway (only s-video).

Yes, the composite, at least on NTSC, should have the ability to artifact as usual. The composite looks very similar to RF modulated channel 3 (NTSC). You still get the bleed and slight shadows on the text characters with composite when Y/C (S-video) is crisp and sharp. When I get the opportunity, I want to experiment with R22 and R27. They are both removed in ClearPic2002, but are needed for RF output. The original resistance values leave a washed out picture if you leave them connected. The trick is to find values for R22 and R27 that make the RF look good, but don't interfere witht the ClearPic 2002 Y & C separate video signals. Not sure it can be done, but I'll try. I figured that I'll put a couple potentiometers in place of R22 and R27 and see what values make sense.

[flashjazzcat]

Interesting info: many thanks. Fortunately the RF mod is removed, but I was asked about composite artifacting on Twitter and realised I had no way to test.