tokumaru Posted June 10, 2012 Share Posted June 10, 2012 Hey guys, today I was modding my 2600 from PAL-M back to NTSC. After removing the transcoder board, restoring traces and removing jumpers, I tested the console to make sure everything was OK. Apart from the messed up colors, which were expected because I hadn't replaced the crystal yet, everything was fine. After replacing the crystal for a 3.579545 MHz one, everything was B/W. Some patterns were visible in areas that were supposed to be flat though. I found another crystal with the same frequency, but different packaging, and it worked fine. Doe anyone know what could have happened here? Both crystals had the same frequency written on them, so maybe the packaging makes difference (the first looks like this and the second like this)? Maybe the polarity? I'm not very knowledgeable when it comes to hardware, and I would really like to understand what happened so that I can avoid problems like this in the future. Another issue with this console is the insane amount of interference. I know that a little RF interference is characteristic of the 2600, but what this console does is ridiculous. I can barely read the Harmony Cart menu. The metal shield doesn't make any difference as far as I can tell, and I'd rather leave it off because it's all rusty and ugly. I replaced the RF chord, soldering the new one directly to the board because the connector was also very rusty, but this didn't improve the image at all. I tried different power adapters, no difference. I have another 2600 (which I have also modded back to NTSC) that works great, I can barely see any interference on its video. Some faint bars on flat colored areas is the only wrong thing I can see, and that doesn't bother me at all. The new console however, has snow and wavy patterns everywhere, and very noticeable bars that shift sideways every few scanlines. what are the common causes for bad video on the 2600? How can I try to improve the image? Any help is appreciated! Quote Link to comment Share on other sites More sharing options...
Rybags Posted June 10, 2012 Share Posted June 10, 2012 Such crystals don't have polarity, no idea if there's any around that do. Possibly there is some specific voltage or current requirement and the one you're using has drifted because it's running off spec? I had to scavenge the crystal from a 7800 to use elsewhere, replaced it with an NTSC one in turn salvaged from some old PC gear and it works fine, except of course it's now black & white. You need the speed to be within certain limits otherwise the TV won't lock onto the colourburst. Missing colourburst = black & white picture. Also, if the scanline or frame frequency isn't within tolerances you can get the same problem. Actually - Pal-M ... does that require the second crystal for colourburst like other Pal systems? Or does it use the same ~ 3.6 MHz clocking as NTSC? The difference being from old Atari 8-bit gear that NTSC simply generates colour from the master clock, Pal systems need the second crystal fed into a seperate pin. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 10, 2012 Author Share Posted June 10, 2012 Actually - Pal-M ... does that require the second crystal for colourburst like other Pal systems? At least in this case, no. PAL-M is fairly different from the other PAL systems AFAIK, being 60Hz and all. Quote Link to comment Share on other sites More sharing options...
Rybags Posted June 10, 2012 Share Posted June 10, 2012 The thing's drifted off spec I'd reckon. The "pattern" - the chosen relationships between line/field/colour clocking freqencies is to minimize that sort of thing, so maybe it's a sign of drift. New crystals are like 4 bucks, so maybe just grab one. Quote Link to comment Share on other sites More sharing options...
iesposta Posted June 10, 2012 Share Posted June 10, 2012 . ... what are the common causes for bad video on the 2600? How can I try to improve the image? Any help is appreciated! If the picture started out ok then got snowy, replace the green "chicklet" capacitor. Fixed mine right up. Even used a different value. Correct is 0.1uf Only green part in lower left looking down on circuit board. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 11, 2012 Author Share Posted June 11, 2012 New crystals are like 4 bucks, so maybe just grab one. The crystal issue is solved, actually. I just used another one I bought a while ago. It was pretty cheap, less than U$1 IIRC! I was just trying to understand the problem in order to not make the same mistake in the future. I guess I should just have a bunch of different crystals! =) If the picture started out ok then got snowy, replace the green "chicklet" capacitor.Fixed mine right up. Thanks, I'll give it a try. Maybe I should try replacing the voltage regulator as well? I've seen people blaming bad video on it... Quote Link to comment Share on other sites More sharing options...
Trinity Posted June 11, 2012 Share Posted June 11, 2012 . ... what are the common causes for bad video on the 2600? How can I try to improve the image? Any help is appreciated! If the picture started out ok then got snowy, replace the green "chicklet" capacitor. Fixed mine right up. Even used a different value. Correct is 0.1uf Only green part in lower left looking down on circuit board. Does radio shack sell that? Do you have the part #? Quote Link to comment Share on other sites More sharing options...
iesposta Posted June 11, 2012 Share Posted June 11, 2012 . ... what are the common causes for bad video on the 2600? How can I try to improve the image? Any help is appreciated! If the picture started out ok then got snowy, replace the green "chicklet" capacitor. Fixed mine right up. Even used a different value. Correct is 0.1uf Only green part in lower left looking down on circuit board. Does radio shack sell that? Do you have the part #? Radio Shack: 0.1µF 50V 10% PC-Mount Capacitor Catalog #: 272-1069 Model: 272-1069 | Quote Link to comment Share on other sites More sharing options...
Trinity Posted June 11, 2012 Share Posted June 11, 2012 . ... what are the common causes for bad video on the 2600? How can I try to improve the image? Any help is appreciated! If the picture started out ok then got snowy, replace the green "chicklet" capacitor. Fixed mine right up. Even used a different value. Correct is 0.1uf Only green part in lower left looking down on circuit board. Does radio shack sell that? Do you have the part #? Radio Shack: 0.1µF 50V 10% PC-Mount Capacitor Catalog #: 272-1069 Model: 272-1069 | Thanks! I have a vader I wanna try that on. Hope it works! Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 11, 2012 Author Share Posted June 11, 2012 Mine is a Vader too. Actually this is my second console with this kind of problem. The first one is in much worse condition though (see ), because not only the video is terribly bad but the TIA is acting pretty crazy, glitching objects randomly. This new one I'm trying to fix looks mostly like that, but with color and without the TIA glitches. Now that I have some idea of what parts might be bad, I might actually try to fix that other console too. I'll buy the parts x 2 and try to fix both consoles. That way I'll have 3 working consoles, and I won't feel so bad about experimenting with one of them. I want to try a composite video mod, things like that. Quote Link to comment Share on other sites More sharing options...
iesposta Posted June 11, 2012 Share Posted June 11, 2012 Concerning repairing Atari 2600's... I was playing SpiceWare's Space Rocks last night, and was marveling how good the display looked on a tube TV. Then I realized I was playing my Heavy Sixer through RF on Channel 3! Deep rich vibrant color with no interference, and I have not replaced any parts, just cleaned the switch contacts. It is a shame that they made such a good piece of equipment — that they got it right the first time — and then had to make revision after revision just to produce it cheaper and cheaper, and introduced poorer video, more interference, parts that fail / break. Don't get me wrong, I like restoring and cleaning up classic hardware the same way people like restoring autos or motorcycles... and if it warrants it, upgrading the video output to composite or S-Video, stereo, etc. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 11, 2012 Author Share Posted June 11, 2012 Deep rich vibrant color with no interference, and I have not replaced any parts, just cleaned the switch contacts. I know what you mean. Ironically, the 2600 I own that has the best picture is one of those with a single-sided PCB manufactured in Brazil (picture). It looks much cheaper than the common double-sided green rev.16 board, but this console is flawless. The picture is perfect, I can't see any interference at all, and there's no shielding or anything. It also has a built-in transformer, so you don't need a separate power adapter, you simply plug it to the wall. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 22, 2012 Author Share Posted June 22, 2012 If the picture started out ok then got snowy, replace the green "chicklet" capacitor.Fixed mine right up. Even used a different value. Correct is 0.1uf Only green part in lower left looking down on circuit board. I bought the 0.1uF capacitor the other day, but when I opened the console today, to my surprise I found something very different from the expected green part: it's a quite big yellow-violet-yellow-white-brown capacitor. After some research, I found that this is a 0.47uF capacitor, so it's quite different from the 0.1uF specified in the service manual. Now I'm not sure I should try using the 0.1uF one... You said that even a different value worked fine, so I wonder if this difference is acceptable. Any thoughts? Quote Link to comment Share on other sites More sharing options...
iesposta Posted June 22, 2012 Share Posted June 22, 2012 I replaced my 0.1uF with a 0.22uF I had. I read that some Atari 2600's have that part as 0.22uF. I don't know enough to tell you it would be ok to go down that far in value. Someone with more electronics experience needs to comment. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 22, 2012 Author Share Posted June 22, 2012 I see... Well, since I had a console in worse condition (the one that glitches pretty badly after a few minutes of use) that also had a 0.47uF C241, I decided to try the new capacitor on it. The old capacitor was cracked actually, so I thought this repair would make a difference. Nothing changed though. The interference is the same, and the 3 main ICs still overheat. Bummer. I checked with a multimeter and the voltage coming out of the 7805 is just fine, so I have absolutely no clue what could be wrong with that one. Anyway, after that I'm not sure the new capacitor will even make a difference in the console that's in better condition and only has the interference problem, since it didn't do anything for the fucked up console and both show similar interference. Maybe this really is related to the mainboard layout? I mean, the one that has the cheap (?) single-sided PCB manufactured in Brazil and doesn't even have any shielding has great picture, not a single dot of interference, while the 2 that have the regular Rev. 16 board show similar interference... this is so frustrating! Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 22, 2012 Author Share Posted June 22, 2012 I think I fried my Atari... =( I tried the 0.1uF capacitor in the good console, since it appeared to work with the other console, and now all I get is a black screen, even after putting back the original capacitor. Damn, I wish I could understand the hardware as well as get the software... =( Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 23, 2012 Author Share Posted June 23, 2012 So yeah, it was stupid of me to try the wrong capacitor, even though it appeared to work in the other console. Does anyone have a clue about what might have happened? What could the wrong capacitor have ruined? Do you think there's any hope for this console or should I just accept that I really screwed up and move on? Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 28, 2012 Author Share Posted June 28, 2012 I was so upset that I ended up buying a new console. Now, this one is in great condition, it looks brand new, I've never seen such a good looking 2600. Problem is... it has the exact same kind of interference as the previous one (maybe this is a tiny bit better, but still)! What the hell, how can this be? Is every console like this? http://youtu.be/h9U5tWMZqJw I'll probably not mess with this one like I did with the previous, I'm done ruining consoles. I just find it incredibly odd that finding a 2600 with good video is so hard! I wish I knew more about these things so that I could understand what the problem really is. Quote Link to comment Share on other sites More sharing options...
iesposta Posted June 28, 2012 Share Posted June 28, 2012 I would like to see the part with the strange capacitor. I'd say the Atari is fine, just not compatible with that TV, but I don't know about Brazillian TVs. Seems the one made for Brazil is perfect? Quote Link to comment Share on other sites More sharing options...
tokumaru Posted June 28, 2012 Author Share Posted June 28, 2012 I would like to see the part with the strange capacitor. What do you mean? You want to see the capacitor itself? I'll post a picture tomorrow, as I just finished packing everything... =) It looks exactly like this though. I'd say the Atari is fine, just not compatible with that TV, but I don't know about Brazillian TVs. Seems the one made for Brazil is perfect? They're all made for Brazil, but earlier ones are (officially) modded from original Rev. 16 boards, while newer ones use a board manufactured here. I haven't opened the new console yet, but from what I can see it's one of the newer ones, with the single-sided PCB (like the one shown here), just like the other console I have that outputs crystal clear video. Quote Link to comment Share on other sites More sharing options...
soonersfan60 Posted September 4, 2012 Share Posted September 4, 2012 Is there any place where I can see a tutorial about how to fix RF on a 2600 clone console? It doesn't match anything I've seen before, and it went from bad snowy pic that would only work randomly, to no pic at all after trying to fix it using parts from standard 2600 machines. Quote Link to comment Share on other sites More sharing options...
tokumaru Posted September 14, 2012 Author Share Posted September 14, 2012 (edited) Is there any place where I can see a tutorial about how to fix RF on a 2600 clone console? I'm starting to thing that all these cases of snowy video could be related to rust or something like that on/in the RF box. I'm hoping that removing it and installing a composite video mod will result in good video. I think I fried my Atari... =( I think there's still a chance to bring this Atari back! After the mishap with the wrong capacitor (I tried a 0.1uF capacitor, like the schematics show, but the original was actually 0.47uF, and it looks exactly like these), I finally got the right one and soldered it to the board. I can see that games are running now, but for a very short time, like a second or so. After that it all turns black and/or glitchy. Personally, I think that the games being able to draw to the screen is a great sign, because it means that the main chips are still working. If something important had fried I would never be able to see a picture, right? So now I need help from you guys to figure out what component that wrong capacitor could have ruined. =) Is this a problem you've seen before (game running for a second and then crapping out)? Do you have any idea of what could be causing this? What is the purpose of that capacitor anyway? I checked the voltage all across the board, it looks normal. No components feel particularly hot to the touch. Since I don't know much about electronics, I don't know what else to test. Any ideas? Thanks again for your patience... But you know how it is when we collect consoles, right? We always want them in the best possible shape! Edited September 14, 2012 by tokumaru Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.