birdie3 Posted October 28, 2003 Share Posted October 28, 2003 I pulled a TIA out of my healthy spare parts 7800 and put it in my 2600 to replace a defective one. The 2600 now works fine. I pulled another healthy TIA from a 6 switcher and put it in my spare parts 7800 and all I get is screen garbage. When I put the old TIA back in the 7800 - it works again. Same with the other TIA. Works in the 2600 but not the 7800. Are these all the same chip or is there something I am missing here? Quote Link to comment Share on other sites More sharing options...
+Mitch Posted October 28, 2003 Share Posted October 28, 2003 I pulled a TIA out of my healthy spare parts 7800 and put it in my 2600 to replace a defective one. The 2600 now works fine. I pulled another healthy TIA from a 6 switcher and put it in my spare parts 7800 and all I get is screen garbage. When I put the old TIA back in the 7800 - it works again. Same with the other TIA. Works in the 2600 but not the 7800. Are these all the same chip or is there something I am missing here? It's hard to say, it could be that the 7800 pushes the TIA chip harder and if the chip is marginal, then it will work in the 2600 but not the 7800. All speculation though. Mitch Quote Link to comment Share on other sites More sharing options...
Robert M Posted October 29, 2003 Share Posted October 29, 2003 Did you try a 2600 cart in the 7800 with the 2600 TIA chip, or a 7800 cart? I suspect the TIA in the 7800 is able to handle the higher clock speed of the 7800. Moving the 7800 TIA chip to the slower 2600 should be trouble free as you observed already. Cheers! Quote Link to comment Share on other sites More sharing options...
DanBoris Posted October 30, 2003 Share Posted October 30, 2003 Did you try a 2600 cart in the 7800 with the 2600 TIA chip, or a 7800 cart? I suspect the TIA in the 7800 is able to handle the higher clock speed of the 7800. Moving the 7800 TIA chip to the slower 2600 should be trouble free as you observed already. Cheers! When the 7800 is running in "7800 mode" it slows the clock down from 1.79 Hz to 1.19 MHz whenever the TIA is accessed, so the TIA is always running at the slower speed. Dan Quote Link to comment Share on other sites More sharing options...
birdie3 Posted October 30, 2003 Author Share Posted October 30, 2003 So is there a different variation of the TIA that is designed specifically for the 7800? I am assuming the 2600 TIA and the 7800 are not the same thing. Quote Link to comment Share on other sites More sharing options...
+Mitch Posted October 30, 2003 Share Posted October 30, 2003 So is there a different variation of the TIA that is designed specifically for the 7800? I am assuming the 2600 TIA and the 7800 are not the same thing. They are the same thing. However there were different "batches" of the TIA chip some of which were buggy. A bug in one of the last runs of the TIA is what causes the Kool Aid man problem in some 2600jrs and 7800s. Mitch Quote Link to comment Share on other sites More sharing options...
Ferris Posted October 30, 2003 Share Posted October 30, 2003 ....A bug in one of the last runs of the TIA is what causes the Kool Aid man problem in some 2600jrs and 7800s. Mitch ...Don't you just HATE that?? Quote Link to comment Share on other sites More sharing options...
Vigo Posted November 4, 2003 Share Posted November 4, 2003 According to the 7800 schematics, the same TIA is used (which gets its 3.58Mhz clock from MARIA). Perhaps an old-type TIA shows different electrical characteristics (power consumption?) than a new one, causing these glitches in combination with the much more loaded 7800 board. Quote Link to comment Share on other sites More sharing options...
birdie3 Posted November 5, 2003 Author Share Posted November 5, 2003 Ha!!!! Quote Link to comment Share on other sites More sharing options...
tiw Posted December 14, 2003 Share Posted December 14, 2003 So it sounds like that new daughter card for teh 2600 that provides SVS and stereo outputs might possibly work in a 7800? Quote Link to comment Share on other sites More sharing options...
cwilkson Posted December 14, 2003 Share Posted December 14, 2003 So it sounds like that new daughter card for teh 2600 that provides SVS and stereo outputs might possibly work in a 7800? Yeah, it works fine. But only for 2600 games of course. 7800 games still output RF video. -Chris Quote Link to comment Share on other sites More sharing options...
tiw Posted December 17, 2003 Share Posted December 17, 2003 Please educate me. I don't quite understand your "7800 games still output rf"? Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted December 17, 2003 Share Posted December 17, 2003 Please educate me. I don't quite understand your "7800 games still outputrf"? The signal for the 7800 is still displayed through RF output. Quote Link to comment Share on other sites More sharing options...
JB Posted December 17, 2003 Share Posted December 17, 2003 The reason being that the 7800 doesn't use TIA for image generation except when it's in 2600 mode. In 7800 mode it uses the MARIA chip. Quote Link to comment Share on other sites More sharing options...
cwilkson Posted December 17, 2003 Share Posted December 17, 2003 I try to be everywhere at once, but the portals keep sticking. JB and Apolloboy, thanks for covering. Yep, I believe all 7800 audio is generated by the TIA chip also. That can be made to function normally, through both the RCA and the RF outputs, but at the price of the nifty stereo output. The RCA will be limited to mono. -Chris Quote Link to comment Share on other sites More sharing options...
JB Posted December 18, 2003 Share Posted December 18, 2003 I try to be everywhere at once, but the portals keep sticking. JB and Apolloboy, thanks for covering. Yep, I believe all 7800 audio is generated by the TIA chip also. That can be made to function normally, through both the RCA and the RF outputs, but at the price of the nifty stereo output. The RCA will be limited to mono. -Chris Hmmm... I guess you could do that. 7800 RF on one plug, 2600 composite on a second plug, and mono audio on a third. I figure the 7800 already has RF out, may as well use that. ... But then, I don't have one. There may be a flaw in the 7800's plug I'm not aware of. Quote Link to comment Share on other sites More sharing options...
cwilkson Posted December 18, 2003 Share Posted December 18, 2003 7800 RF on one plug, 2600 composite on a second plug, and mono audio on a third.I figure the 7800 already has RF out, may as well use that. ... But then, I don't have one. There may be a flaw in the 7800's plug I'm not aware of. yeah, that's the general idea. -Chris Quote Link to comment Share on other sites More sharing options...
JB Posted December 18, 2003 Share Posted December 18, 2003 7800 RF on one plug, 2600 composite on a second plug, and mono audio on a third.I figure the 7800 already has RF out, may as well use that. ... But then, I don't have one. There may be a flaw in the 7800's plug I'm not aware of. yeah, that's the general idea. -Chris I don't follow why you can't have stereo sound.Am I missing something? Quote Link to comment Share on other sites More sharing options...
cwilkson Posted December 18, 2003 Share Posted December 18, 2003 I don't follow why you can't have stereo sound.Am I missing something? It's because the two channels will be shorted on the 7800 motherboard. I think. There's only one audio channel in the RF modulation. If you split the channels for stereo, you'll lose one channel in the RF. This isn't a big deal if you're willing to run both RF and steeo cables for you 7800 games. But if you want to use the RF for your audio, then it's an issue.... -Chris Quote Link to comment Share on other sites More sharing options...
birdie3 Posted December 19, 2003 Author Share Posted December 19, 2003 And now for something completely different.. I found out from a reliable source that the TIA is exactly the same in any variation of 2600 and 7800. Apparently the 7800 is rather chip sensitive and a TIA that works in one may not work in another. I can't imagine why nor do I want to rip out all of my TIA's to find out which one I could replace it with. Now I am stuck with an expansion slot 7800 and no TIA to put in it. Quote Link to comment Share on other sites More sharing options...
cwilkson Posted December 19, 2003 Share Posted December 19, 2003 Now I am stuck with an expansion slot 7800 and no TIA to put in it. That's tragic! Really. I could get you a TIA chip, but I don't have my 7800 here, so I couldn't test it. How do you have a 7800 with no TIA? Did it blow up? Or did you steal the chip for another console? Just so I don't have to go digging through tons (literally) of docs, what's the incompatibility? If you have the old TIA that came witht he system, what's the date code on it? I might be able to find one from the same lot. (or a different lot if necessary.) -Chris Quote Link to comment Share on other sites More sharing options...
JB Posted December 20, 2003 Share Posted December 20, 2003 I don't follow why you can't have stereo sound.Am I missing something? It's because the two channels will be shorted on the 7800 motherboard. I think. There's only one audio channel in the RF modulation. If you split the channels for stereo, you'll lose one channel in the RF. This isn't a big deal if you're willing to run both RF and steeo cables for you 7800 games. But if you want to use the RF for your audio, then it's an issue.... -Chris Ah. Didn't think of that, because all my stuff runs through a stereo anyways. I've even hooked a Speak and Spell up to the stereo once, just for the hell of it. Quote Link to comment Share on other sites More sharing options...
birdie3 Posted December 20, 2003 Author Share Posted December 20, 2003 I stole it for one of my six switchers. I just need to figure out which one I put it into. Quote Link to comment Share on other sites More sharing options...
tiw Posted December 21, 2003 Share Posted December 21, 2003 Reading all the posts here it would seem that you would need a piggyback s video card for the Maria chip rather than the TIA chip? Is this correct? To me it I think it would be nice to have clean sharp video on both the 2600 and the 7800. I wonder if the chip used in the Jag which provides RGB, s-video and composite could be sandwiched in somehow. Quote Link to comment Share on other sites More sharing options...
JB Posted December 22, 2003 Share Posted December 22, 2003 Reading all the posts here it would seem that you would need a piggyback s video card for the Maria chip rather than the TIA chip? Is this correct? Nope. In 7800 mode, MARIA generates the video, but TIA generates the sound. In 2600 mode TIA does both video and sound. So any way you slice it you need 2 parts. Quote Link to comment Share on other sites More sharing options...
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