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rmzalbar

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Everything posted by rmzalbar

  1. Very nice 600XL. I acquired one early in the year, and finally got around to giving it a similar treatment over the last week. Yours came out very clean, I was never confident enough to touch the aluminum on any of mine. Mine has the same AWC keyboard - it's pretty decent, doesn't block if you hit the keys off-center the way the ALPS keyboard on my 800XL somewhat does. Mine had a cracked solder joint on the "M" key. I've been fortunate that the two XL machines I got both happened to come with mechanical keyboards The keys just work and no worries about membranes, but I shudder to think what I'll do if any of the switches ever need to be replaced. I game mine the U1MB and the Super Video 2.1 treatment. I used FJCs 3-wire 64k mod instead of the Lotharek one. I removed the battery holder from the underside of the U1MB to allow me to mount it about 5mm closer to the motherboard to take some pressure off the keyboard ribbon. I intend to modify and reinstall the shield again at a later point.
  2. Looks like after Super Video 2.1, the chroma and luma communicate through a three-component series of 75R, .001uf, 75R, combo. The capacitor and resistor form an RC filter and probably filters (I suppose) the luma out of the chroma. Worth a try? This is from 800XL SV 2.1 (the pre-Super Video schematic also showed that series to combine the luma and chroma, but of course there's no chroma to pin 5.) Also note the composite-disable switch I mentioned in that string. You likely won't have 75R resistors, but you can just use a single 150R and capacitor in series. The only reason for the order of the three is to set the composite output impedance, which is in the middle of the series, to 75 ohms.
  3. I use a vintage flippy puncher, but since I've started remastering flippy disks from images (with inket repro labels even), I installed into a 1050 and a 1541 a write-protect sensor disable switch so I can master flipsides without punching them at all. When I was a kid.. I used a robust steel paper hole punch, using another disk for reference. Not as pretty but works fine.
  4. It doesn't happen if you use the optional composite video disable switch that's part of the Super Video 2.1 mod. At least, not on any of my three machines. If I leave the composite enabled, it does look like yours. This can only be from luma leaking back into chroma from where they are combined to make the composite. So if you want to cause it on purpose, just tie the two together with a large value resistor at the output of the UAV. You may need to experiment with resistor size.
  5. SLA printers have become cheap enough at last. I'd bet replacements printed with one might be good enough, if the resin itself proves tough enough.
  6. That is interesting. Clearly there is some color leakage into the picture, though it isn't as intense and the luma isn't getting blended as it does with composite. It looks like it does on some of my CRTs when I don't disable composite while using S-video (which is very faint compared to yours, but has a little color like that and makes the picture less sharp) using Super Video 2.1 mod on XL. The luma leaks into the chroma from where it's combined to make the composite and permits some artifacting. So, maybe you could get it working on the UAV by using the composite output pin in place of the chroma pin from the UAV. That's the old "use composite as chroma" trick some people do with their XLs when they don't feel like going in to wire it up. It works well on many CRTs. Probably it would be better to blend it in to the chroma through a resistor rather than using the composite full-strength.
  7. None of my three XL Ataris with chroma pin hooked up for s-video, display artifacting when connected that way. I have six different CRTs, too. None of them are UAV either. I don't know what's going on with yours, but "people" are not "repeating rumors."
  8. Oh WHAT? PBI wire mod whaaat? Man, I was *just* in my 800XL yesterday. Damn my eyes for deciding to keep the shield.. 😄 I should put all the recommended PCB mods for each model in one place.
  9. I cracked my 800XL back open to check for the mistakes mentioned, but I did it right the first time. Also.. testing my 800XL, the chroma level now seems fine. I think I just get spoiled if I play with my 1200XL, or my chroma-boosted 2600 too much.
  10. Valuable! Thank you, I didn't know about these corrections. I'll review my 800XL board, this may be the answer for me.
  11. I found this thread in a search for help, and although old, I'll post the solution for anyone else who follows my path and ends up here. There is indeed an error in the Super Video 2.1 600XL guide. The switch needs to be wired to the vacated L12 holes, not L13 as indicated in the guide. The inductor already present at L13 should be left alone - if you remove it, you will lose the RF video. Also, R134 is missing from the layout drawing. It's right between R133 and R132, just below the transistor Q8. These changes should fix the missing composite video created by this error. I did not experience any loss of color saturation with Super Video 2.1 on the 600 XL. Video looks excellent on svideo, composite, and RF. I do have an 800XL with poor saturation as an earlier poster mentioned, but it was already poor before I did the SV 2.1. I plan on adding the color saturation boost circuit the 1200XL uses to improve this. Personally I like the saturation boost of the 1200XL. I'll post a guide after I work this out in case anyone else wants the boost on the other XLs.
  12. Retrobriting worked great on my 1200XL, and the original keyboard membrane can usually be repaired if it's failed in the typical way, at the point where it interfaces with the connector. Even if it can't, there is a new-manufacture replacement membrane available from Best Electronics that worked perfectly for me (though I saved my original membrane too as it turned out to be repairable.) When retrobriting, disassemble the shell completely, separating the brown and smoked panels from the shell so you can treat the white plastic only.
  13. I do have my limits: I will leave the cardboard shield out of a breadbin C64 so those hot chips will live longer; however, I always at least replace the bottom shield since these old PCBs lack even a ground fill. I'll try those pokes next time I have the 1200XL up on the desk. I can definitely confirm the faint herringbone is not my imagination, though I don't notice it unless it crosses my mind and I look for it. I finally ordered a DS1054Z today after having been without a scope for several months (I was only borrowing one, I never owned one.) So pretty soon I'll get down and dirty with some ceramic capacitors and see what I can do about it.
  14. I doubt the saturation boost would do anything in the black areas of the screen like that. I believe all it does is crush the colorburst reference on the front porch during hsync, which shouldn't cause anything to appear in the black areas of the screen. Any noise leaking into the composite signal from elsewhere in the Atari that raises the level up from black might cause it to look like that in the darker areas of the screen. You can see that the noise covers the entire screen and seems to have patterning that changes in different areas of the screen. I'm not clear on which areas of the screen are not addressable by the display on an Atari (borders of the screen?) but if the noise is visible in such areas, it wouldn't be a logic problem (like video ram.) The patterning suggests that digital noise from other operations is leaking into the video signal, either from failing digital componnts (GTIA, transistors, diodes) filtering components (capacitors) or poor grounding somewhere.
  15. Is this why I usually see a yellow screen during a power-on or reset of my 1200? It doesn't appear to have any ill effects.
  16. No. In the photo, the Traco is not attached to the heatsink. I left the heatsink there for the benefit of the rectifier.
  17. I would like to cap this off by saying that I did contact Lance, and he was very helpful. We had some issues with USPS delivering to the wrong address and slowing things down, but ultimately, he was able to provide me with a Venture cart that works! I'm completely satisfied now.
  18. I was mistaken when I said the Vic-II handles RF generation. That's not true of course, it generates Luma and Chroma.
  19. There is a similar project for the C64 called VicII², and indeed, it has every single one of the problems you are listing here. To get around all of the issues, they had to go with relays instead of solid state logic (in part so the power is switched) and a side-by-side board as opposed to a stack; and even with the side-by-side layout, the need for heatsinks on the ICs means that it will only fit in the taller breadbin-style models that have enough space under the keyboard. Perifractic has a great video on how they developed it and dealt with each of the challenges that is worth a look as there are a lot of parallels there. The end result was a brute-force approach that turned out to be physically imposing and pretty expensive. And, of course, for North Americans we need a monitor capable of full PAL decoding, not just 50hz capable as the case would be with the Antix. I have one in just one of my breadbins and I really like having the convenience of it, but it was a little finicky to get going. Crucially, the Vic-II also handles direct RF generation, so switching and tuning the clock generator and switching the RF output also had to be done which isn't really the case with the Antic since some of those functions are on GTIA. Given the expense and limitations, I could see where an FPGA Antic implementation could be the right drop-in solution in this case.
  20. Nice, thank you for coming back to post the solution.
  21. Hi Everyone. A lot has happened in the thread since I posted my issue. I thank everyone who is concerned on my behalf; paying a retail price for a cartridge game and finding out it isn't quite ready go isn't an optimal experience. Coming here and seeing that the author has stated it would be fixed is concerning because, while I didn't see this thread beforehand, someone else who did would have been making a buy decision with false information. Regarding dumping and sharing - Yes, certainly when I was younger I pirated the heck out of games, but I'm not the same person I was when I was a kid. I evaluate things differently now. I care about the health of the community and the fortunes of others, even those who aren't perfect, and being trustable is important to me as well. So I have formed principles based on that, and they don't change even if the author's behavior is not perfect. I see that as an issue to handle separately, it is not for me to mete justice in that way. I did send an email to Lance, and he is providing support. I'll let you guys now how it works out. Thank you!
  22. It looks like a common issue with the 6-switcher models using the 4050 to buffer the firebuttons. The reason 4050 is set to 3.6 volts must be to set the video levels, which is mostly what that chip is concerned with. The firebutton doesn't need to be level shifted, though. A few people "fixed" it by bypassing the 4050 with the firebutton lines (which is fine, as the 4-switch models did simply that.) Why is 3.6v not good enough to prevent firing in the first place? Not sure, but possibly an aging TIA chip or still a marginal 4050 or socket. Here's the thread on the issue:
  23. Oh, crap. The 4050 gets its power from a voltage divider composed of resistors R231 and R232, with a result of 3.6 volts. So that is normal. I'm sorry I didn't check this earlier. So it looks like the purpose is to intentionally level-shift the 4050's output to TIA to a range of 0v - 3.6v. I'll think about this a bit more..
  24. Hi! Yesterday I bought 4 separate items (all of them carts,) but at checkout I sent an invoice request for combined shipping. That request is still pending, but today eBay is auto-warning me to pay to avoid an unpaid item claim. If you can't do combined shipping, please let me know. Thank you.
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