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Dr Memory

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About Dr Memory

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  1. I installed the video mod shown in the picture earlier in this thread, and it works great! I had to use a 47uf cap because I didn't have a 22uf as shown in a write-up I found nor a 220 like the one shown in the pic. Basically, I guessed that the exact value didn't matter, and sure enough, it works just fine. Minor puzzle - I did not have to install a diode to make it automatically sense Composite vs. S-Video. I tried it without, and it worked. Now I'm wondering if that was needed on the 800XLs? Oh well, no problem either way, I am happy. It works and looks really good.
  2. I've been working on this for a while now. It's a video test utility, meant to stress out CRTs a bit (but it works on all monitors of course). I think it's ready for people to beat on it. Feedback and bug reports welcome, but please be kind. vstress.xex vstress.txt
  3. Well the project isn't quite done still. I finally got all the chips replaced and the 64K upgrade working to my satisfaction, then remembered to my horror that I still had problems with the keyboard to deal with. Non-functioning HELP, BRK, left shift, and control keys, to be precise. Most of those are on trace 9 but one wasn't, so I was a little puzzled. Last time I took an XL keyboard apart, the springs sproinged. I suppose that isn't a real word but it gets the correct idea across. So this time I watched all the videos I could find, first. It turns out that the trick to not having that happen is really pretty easy - you need to have the keyboard sitting on your work area keys down when you remove the mylar. That's it. Same thing for the function keys, which I did first. All the little springs peacefully sit in their little spring holes if you do it that way. You still have to be a little careful but really, it was a lot easier than expected. I was able to track down the problem pretty easily with a multimeter in continuity test mode. It turned out that the traces on one end of the mylar had broken on the fold. Not visibly, but they no longer made connection. The odd assortment of dead keys was because there was a physical component to the problem - only keys on trace 8 or 9 that were also past the fold where the breaks happened were impacted. So that's why left shift didn't work and right shift did. Huh. Learn something new every day. Easily fixed with a Circuit Scribe conductive ink pen from Amazon. Now the keyboard works. Yay! All that's left to deal with is video. The quality is good already, but I want to enable chroma/luminance and have it auto-switch like my other XLs do. So I guess looking into how to apply that fix to a 600XL is next on the agenda. Getting close!
  4. Ya I had the socket and already had everything ripped apart, so figured I might as well. Even though I have no specific plans for such a thing at this time.
  5. Thanks! I've got the Hakko. Basically, I had to use both the pipe cleaner and the thicker cleaning tool that you use after you remove the tip. I didn't realize how much power the thing had lost until I got all that sorted out. When I first tried to stick the tool in there it wouldn't even go in it was so clogged and degraded. I've been emptying the solder repository every session or two and thought that was all that was needed. That'll teach me to assume! Well, briefly at least. Even with the little problems with the 600XL project, I don't regret the desoldering gun purchase - it was life-changing! I never would have even attempted a project like this in the past. Oh, I just finished upgrading the 600XL to 64K. I used one of the methods linked, the one with 3 wires. It really doesn't look too nice - apparently I still need to learn how to cleanly solder wires to bent-up pins and pins on chips in sockets - but it works. Little adventure - at first it didn't work, so naturally I was cursing myself and checking and rechecking my work, as it doesn't look all that tidy. I finally thought to try different chips. Sure enough, 2 of the 6 chips I bought from eBay are bad! On the bright side, now I can use Sys-Check to figure such things out. So yay, it works, and it's socketed! Just like a real boy er 600Xl.
  6. Update on my little 600XL project! It was taking a while for the DRAM to get here, so I decided to re-chip the board. Yes, the whole board. All 23 chips. This is by far the most ambitious such project I've ever taken on. In the end, it worked out, but there were... issues. Here we have the same system (as shown on post 10 above) with all the chips desoldered. Ugh. Full disclosure - I did this as well as I knew how, and still broke two chips and a capacitor. It turns out that my desoldering gun has multiple levels of cleaning that it may need, and I didn't understand that it needed the full teardown and filter replacement until I had pulled up a couple of traces. Oops. Anyway, here it is, after the de-soldering (de-chipping?): I certainly learned a lot by doing this. Next time I have to remove a socket I think it'll go a lot more smoothly. However, I hope to never have to de-chip a whole board like this again! I snapped a capacitor, the one to the left of GTIA, while I was trying to pry GTIA out. It wasn't quite as strong as expected. I wasn't able to find an exact replacement - I don't know where to get those weird axial aquamarine caps Atari used on these - so I replaced it with a more common disc cap. I checked the voltage of the original and this should be fine. The bigger problem is, I killed the 74LS14 and the 74LS138. Oops? Both of these had to do with the desoldering gun not having the effect I was expecting, and me not understanding that until too late. Lesson learned - if it seems like you're getting less suction, you are, and never ever force things when pulling out a chip! I didn't have either in stock and had to order and wait, as all of the Radio Shacks in my area are gone, as well as the Frys. Oddly, they still both got here before the DRAM. /shrug So here is the end result of the socket installation: You can see the replacement cap on the top of the left picture. Those yellow jumper wires on the bottom of the board are the other thing I had to fix - apparently I delaminated a couple of the holes on the 4050 while trying to desolder the chip. Again, I tried to force things when desoldering didn't feel right. It was a little challenging to fix, as not all of the problems were visible, even with a loupe - I had to trace things out with a multimeter to figure out why I was missing colors and luminance values and such. Things like the SuperSALT cart are great for normal problems but not so helpful if you have a lower-level problem like a chip with impaired connectivity. Anyway, I didn't give it more memory or better video yet, I just thought someone might be interested in seeing my socketing adventure. I think if I ever get another non-socketed 600XL I'm just gonna turn around and re-sell it. What a pain! Final toll - 23 sockets (various sizes), 1 capacitor, 2 logic chips, a few small lengths of wire, and a truly impressive headache.
  7. That sounds just like mine. PAL, Video circuitry populated, DIN connector present and working but no Y/C yet, and no freakin' sockets. That last one is the only one that bugs me - didn't previously even know it was a possibility! Well, now I do. Thanks for the links.
  8. Thanks again Mazz, that looks well worth doing. I'll probably wait until I get the memory going properly though, in case things go bad. I assumed that Sys-Check would allow me to use the external memory function even on a sad 16K 600XL, but it appears that tf_hh really means what he says about it not being happy if your 600XL lacks 64K of main memory. Even with it set to use 64K from the board instead of system memory + the 512K expansion, well, it actually doesn't and just goes to system self-test. Fair enough, the manual actually said it wouldn't be happy in this circumstance. Oh well. The reason I dug into this is I was hoping to use my SIDE3 cart on it, because most of my validation and test programs are on there. No joy, so I copied them to Ultimate, but it's a bit fussier, AND it turns out most of my stuff needs more RAM than that. Even, to my surprise, some things I wrote. 16K isn't very much RAM! Oh well, maybe I'll spend some time socketing things while I wait for my 4464s. I've got a dead 1050 to fix too, so not like I'm bored.
  9. Ok, I ordered some 4464s from eBay. It looks like most of the upgrades require those. Bummer as I already had 4164s in stock, but so it goes. I'm pondering the precision socket thing. Several people here seem to swear by them, but I haven't actually had any trouble with the good old cheap sockets, ever. The only real advantage I can see for switching is the lower profile but perhaps I'm missing something. To be fair, the low profile argument is a pretty good argument for something as crowded as a 600XL, but in general this reminds me of the "you must immediately replace all of your capacitors" thing. Oh, a little more on the "no socket" thing. I saw in a couple of threads here that some very late PAL 600XLs have partial sockets or no sockets. I guess I just got lucky. There is no date code on the bottom of my machine, but it says this, in various spots: Serial No. 72RHA B-035 8409654 Made in Taiwan I don't know how to interpret the serial number or the B-number or anything, perhaps there is a clue there for those more knowledgeable about the history of these things? And just for the humor of it, I happened to notice this on eBay today: https://www.ebay.com/itm/ATARI-600XL-COMPUTER-Retro-games-vintage-serial-no-72RHA/284234009218?hash=item422daaca82:g:QZwAAOSwrLZgVhug That is the same machine I just bought, from the same vendor. WTF? When I say the same machine, I mean that even the pictures match, though it's listed for more than mine was. I'm thinking the vendor has gotten his wires crossed somehow. Maybe he had two? Very odd to see the same serial number for sale, that I'm holding in my hand...
  10. Hmmm. I am, and I think you're correct. I actually checked first, and saw where it said "Sys-Check also works fine with an Atari 600 XL", but somehow managed to miss the rest of the sentence. Oopsie. So that's probably a bogus bad memory report I'm getting. I'm still gonna have to socket the DRAM as a minimum, and probably a lot more than that if I'm gonna put in a video upgrade as well.
  11. Wow! Thanks for the memory upgrade info, guys! I will almost certainly do that - I never intended to live with 16K. I did a little more testing on this thing. Three keys are dead - left shift, BRK, HELP. Odd assortment. The memory passes the internal test, and SALT, just not Sys-Check. I certainly trust Sys-Check more! I was shocked to see all that red. I have some known good DRAM chips and a memory tester so should be able to figure out what's going wrong. However, I hit a snag. It took me quite some time to disassemble the thing, and I found to my surprise that it is not socketed! I thought all 600XLs were socketed? So I can't just pop the DRAM and test it, there will be some work involved. Huh. So that's going to slow me down a bit. On the bright side, it already has the video components filled in, which also seems unusual - I expected to have to get a kit or a bunch of discrete components and do that myself. Maybe because it's PAL? Are PAL 600XLs known to have their video stuff already populated and no sockets? The picture quality isn't bad, but is composite only, no Chroma nor Luminance. I'm letting it rest for a little bit here, had to use WD-40 to get a couple of the screws loosened. It seems likely this thing was never opened before. But if that's the case, then I'm very confused about the video situation. I'm also very confused, almost shocked at the lack of sockets. Guess I need to do some more research here. And some desoldering, of course.
  12. Well. This doesn't seem like a good thing. It did say "untested"! Interestingly, it boots, and I get a plausible response from ?FRE(0) (13326), but as you can see, it is not a happy camper. Keyboard issues too. Not sure what else yet. Oh well, opportunity to learn things!
  13. There was another one not too long ago that sold for over $400 also. I don't really get it. I bid on this one but they passed the max I was willing to bid like 2 days before the auction closed, and I was already feeling guilty considering spending as much as I was on such a thing. Oh well. I'd like to get one someday because the very first Atari I bought, new and from a store, was a 1200XL. I sold it because friends convinced me I really wanted one of the older models for compatibility with things. It was probably the right decision at the time, but now I'd like to get a replacement for sentimental reasons. The prices are just insane though, and frankly, it just isn't as important to me as it obviously is to others. Isn't that a good chunk of the cost of a 1088XLD w/daughterboards? Sheesh!
  14. I replaced it with a #3 x 1/2 in Flat Head Zinc Wood Screw. I think a #4 would have been all right as well, and I probably could have gotten away with 5/8 in but it would have been tight. The head on the #3 fits in the recess nicely, so I gained a little depth from that. Cartridge now seems stable and much sturdier. Still my favorite utility cart! I got a little frustrated in Home Depot when I got jostled and dropped (and thus lost) the original screw so went with the best match I had at that time. Home Depot on Saturday afternoon is not the most mellow place to shop. That's not really an Atari-related problem though.
  15. Did I make a pun? Yes, I did. If you expect me to apologize for that, well, I'm a frayed knot. Anyway, I noticed that my SIDE3 cart was having a little trouble. When I inserted it into a machine, it didn't always work right away. I often had to remove and reinsert it and/or jiggle it. So I took it out and fiddled with it a little and realized that it wasn't connected solidly. In fact, the back pulled off with minimal force, and no screwdriver involved. Huh. Looking at it more closely, I realized that the screw had eaten some of the plastic from the board side of the case, and as there wasn't much overlap between the screw and the case, it was enough to make the connection loose. I tried to screw it in and it just turned... That may have been an error to try but it was already hosed so I probably didn't make it worse. Looking more closely, I realized that the screw tapers off pretty quickly, and only penetrates into the hole on the board side a little bit. Unfortunately, I dusted off both sides a bit just so I could see what was going on prior to realizing I should take pictures, but here is what I found anyway: Just the screw. Note the abrupt taper. Measurement of the screw. The threaded part is about 1 cm, the tapered part maybe 2-3 mm. With the screw in the case, it only sticks out a little - that little bit is all it can use to attach to the other side. Maybe 1-2 mm? Then on the other side, where the board is, the board sticks out over the plastic hole a bit. So there is only a tiny bit of overlap between the part of the screw that reaches the hole and the hole. Seeing this, I guess it's no surprise that the screw wore away the plastic enough in normal use to basically fall out. I guess if I can find a replacement screw with the same diameter but without the taper, I should be able to fix this pretty easily. I'll go to Home Depot later and see if I can find one. I love my SIDE3 cart and have no complaints, just this little mechanical challenge. I posted in case others might have the same issue. If someone knows what size that screw is, it would be helpful to know that so I can skip the store search part of this. If I screwed up the metric stuff, sorry, I was raised on the English system, but this stuff is so small that trying to explain it using fractional inches seemed like a bad idea.
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