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About rmzalbar

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  1. I installed Traco to my 1200XL and my 1050s. All units now run dead cold. The final result was satisfying, but I had two problems. 1. They don't really fit into the footprint of a TO-220 package as their datasheet claims. Getting them to fit without interfering with the original heatsinks was a bit of a pain. Be very careful when bending the legs to get them to fit; they are tiny and fragile. Too tiny and too fragile for a power delivery component in my opinion. On one of my TSR 1-24120 for the 1050, after only a bit of bending, the legs broke off the pcb internally, up in the soft silicone potting. I had to unpot it and solder new legs onto it under a frigging microscope. It was a real pain, and the non-ROHS solder I had to use then posed an additional challenge in keeping them from unsoldering themselves again when I went to solder the unit down to the mainboard afterwards. Do not allow any stress on them to pass up into the potting and only bend once. I was more careful with the rest, but it still felt like a delicate situation. Also, make sure the cases sit flush on the mainboard for support and stability. You really don't want them suspended on those crappy legs. OH yeah, and I had to grind out a relief at the corner of the heatsink where the screw goes through the PCB to the bottom case. 🙄 2. On the 1200XL, I *thought* I detected a very faint, SUPER faint, herringbone pattern barely visible on certain darker screen colors. I was definitely overscrutinizing it and it may have been there already. Still, I counted the switching frequency (500khz) against the dotclock to see if it was theoretically possible, and realized it should be visible at 33 beats per horizontal raster, which is about what I *thought* I saw looked like. The thing is, when I laid my mainboard out on my bench, got the shielding off, and hooked it up again, I couldn't find any herringbone at all. Nevertheless, I added a pair of my lowest ESR capacitors I had on hand across the original 22uf axials on the 5v outputs just in case. Zero issues. I was prepared to add capacitors anyways. With the above two things in mind, you may decide it might be too much of a hassle given the cost of the Traco parts. (I'm one of those sociopaths who tries to keep the shielding intact, and the RF modulator installed. I have U1MB and supervideo XL 2.1 hidden under there.)
  2. Yup, mine has been sitting in COVID hell for a month, but the tracking updated to in-country today. Getting excited!
  3. That did occur to me. I was wondering if Bryan might pop in and say "Oh dear, you seem to have a dry joint on a pre-amp bias pin.." or somesuch. I'll crack it open and take a good look. I do also have two other UAVs destined for the A8s, but those are of the plugin type so there will be a bit of farting around getting one connected to the 2600.
  4. I haven't tested with S-video yet (I don't have a DIN jack for the console.) Curious if that would change anything since the colorburst is separated from the luma signal. However, I can see in your screenshot that you have a much deeper sync level than mine, with the sync level peak-to-peak about double the amplitude of the colorburst. It looks much more like the final tuning I arrived at for the Odyssey 2.
  5. Here is a scope capture of my video signal from UAV. This is at the far end of the composite cable, measured across a 75-ohm resistor termination in lieu of being plugged into the TV. It looks like the sync tip is not nearly low enough, less than half the amplitude it should be, relative to blank. The colorburst even slightly exceeds it. Everything else looks like it's about the correct scale, with full white about 1 volt above blank. This is definitely the cause of my weak sync issues. Is there something external to UAV that could affect this, perhaps in getting the sync signal out of the Atari video circuit to the UAV? This is a 4-switch 2600. For comparison, I can replicate the same symptoms from my Odyssey 2 console by detuning its home-made composite amplifier so that it clips the sync signal too close to the blank level the way this one is. My symptoms are that all of my displays have some amount of sync instability, with some of them not syncing at all. Worse with brighter screens.
  6. None of the usual video mods for the Odyssey 2 gave me good results. I ended up designing my own from bits and pieces of amplifier examples I found on the web. It was an eye-opening experience. The Solarfox mods work okay, but they are emitter-follower which, although a stable and predictable option, provides no voltage amplification and in fact puts out a slightly dimmer picture than the source due to diode drop in the transistor. It also strips all DC bias from the signal, which not every display is happy with. The only way I could get a stable, bright picture on all displays under all conditions was to use a two-transistor amplifier with a pot for DC bias and a pot for amplification. I needed a small positive bias with a well-defined sync level and 0.7v from black level to white. I will check the UAV output again, now that I know what works.
  7. Well this is interesting, I encountered this issue again today when I built a composite output circuit for Odyssey 2. This time though, I had it on a scope AND I had an output level potentiometer. There was a ton of DC bias so I ran it through a capacitor and then gave it a schottky clamp to bring the sync level up closer to ground. Anyway, so what was happening? While tuning the output level, I adjusted the level up too high, the sync level got blown up to nearly meet the black level and bingo, sync problems and that same flag-waving effect. I'll have to take another look at the Atari UAV output now.
  8. It is, but I followed Bryan's advice from the manual by moving the boost to the opposite side of the decoupling capacitor.
  9. The mod does looks good aside from the sync issues. It's perhaps not as color saturated as the RF with the chroma boost, but it's very bright and clear. I'm very glad I was able to keep the RF and the chroma boost circuit. While I was at it, I added an RCA jack for RF so I could finally ditch the hardwired RF cable. I really hate those hardwired cables. After a bit of work with some copper tape in the RF area of the board, even the RF is looking better than ever. I will order up an S-video bulkhead jack and also an RG8 F-type bulkhead jack to replace the RCA RF jack I installed today, as I noticed that I did get a slightly cleaner picture when I plugged CATV coax straight into the board during testing. I went through the CRT repair faq, and the only thing that seemed to resemble my issue was sync loss on bright screens being a common issue related to inadequate filtering on the sync splitter in the TV itself. I'll check into that when I have nothing to do for a day.
  10. I reimplemented this because my placement of the UAV turned the RF into a snowstorm. Now the UAV is under the top shield and I'm tapping the signals from the resistors instead of directly at the socket. I'm also getting 5v and GND from somewhere else instead of from the RF's power supply. This cleaned my RF up just fine, but nothing changed with the composite issues I've described. I scoped the TTL signals to the UAV and the video output and they LOOK fine. Maybe someone will recognize these symptoms and tell me where to look in my TV or otherwise. Since it's affecting at least two different devices, I'm inclined to believe the Atari is a little bit non-standard.
  11. Is there something non-standard about the way the Atari 2600 syncs? After installing the UAV mod and using the composite output: - My CRT television shows a "flag-waving" horizontal distortion effect in the top 10% of the screen with bright playfields - Most of my CRT monitors lose sync for a frame or two on bright color flashes - Two of my monitors, both JVC A13SU, fail to sync vertically at all with the 2600 (rapidly rolling picture.) These things don't occur with the RF output. This is on a four-switch 2600, all five lines taken from the TIA socket. Any ideas?
  12. I had heard of Amiga but had never seen one. I had heard rumors of arcade-quality Dragon's Lair and other magic happening on it as an early teen, but also saw mid four-digit dollar amounts in magazine ads, so it was definitely not worth hoping for. But then I turned 15 and could have an after school job. That summer a friend's older brother finished his Air Force service and came home with an A2000. He gave us access to Shadow of the Beast, Armour-Geddon, Blood Money, Lemmings, F-18 Interceptor, Dungeon Master, Dragon's Lair, MED, DeluxePaint, DigiPaint, Imagine 3D, and SIRTIS.GIF (lol.) It's hard to say if any one of those things pushed me over the edge, because they all hit me at once and they all knocked my socks off, but probably Dungeon Master, F-18, and Imagine most of all. I bought an Amiga 500 several months later (as soon as I made enough money at my part-time drugstore job.) Over time I expanded it with an AdSpeed and an AdRAM. Wanted to do 3d rendering, definitely couldn't afford the mainstream accelerators and hard disk expansions, so I got by with a doublespeed 68000 and a big ramdisk with two floppy drives.
  13. I plan to make controller board from these schematics. Looks like there's a difference between the Jerzy and the SMIRK schematic, so I'll look hard at the photos people have posted and reason out which is correct. I have two of the most recent AtariMax happy boards. Although they don't have a header for the controller board like the original happy, all it is doing is watching the address decoder and clock, and setting SO under appropriate circumstances. The only question is, does the AtariMax expose the same address decoding on any of its GAL pins, or do I need to ignore the GAL and just add my own decoder to the controller board? Does anyone happen to know? If I use my own decoder anyway, It would be a solderless solution as a socket adapter to stack under the socketed 6502 on the Atarimax board.
  14. I'm interested in purchasing one of these carts. Do you sell them?
  15. Right, well some games definitely won't run in the other's format, but I don't think that has anything to do with whether it's a native PAL/NTSC system or the override mode is used. Last night I did run a few games on my PAL A500 motherboard and compared them to the NTSC Amiga in PAL mode, and I couldn't detect any difference at all. Yep, Alley Cat on a PAL system runs at 25 FPS instead of 30, and all of the game timing follows that. It would be neat to see the switcher get completed. I installed a VIC-II switcher on my C64, and it totally rocks.
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