Longhorn Engineer Posted November 30, 2009 Author Share Posted November 30, 2009 I'm wondering if ASEL on the FMS6400 should be low. Does luma really need the 6dB gain? How does it look without the above changes, but with ASEL tied low? I would think this would be ideal as the FMS chip runs hot; lowering the gain should cool it off a bit. I should have some time tonight to do a few more experiments. I'm also wondering if anything ever came of this experiment. When I was building the circuit without it the picture was so dark you couldn't make anything out. Parker Quote Link to comment Share on other sites More sharing options...
Ransom Posted November 30, 2009 Share Posted November 30, 2009 I'm wondering if ASEL on the FMS6400 should be low. Does luma really need the 6dB gain? How does it look without the above changes, but with ASEL tied low? I would think this would be ideal as the FMS chip runs hot; lowering the gain should cool it off a bit. I should have some time tonight to do a few more experiments. I'm also wondering if anything ever came of this experiment. When I was building the circuit without it the picture was so dark you couldn't make anything out. Parker Ah, good to know! Quote Link to comment Share on other sites More sharing options...
cwilkson Posted November 30, 2009 Share Posted November 30, 2009 What's the shipping status on the 2600 mods? One was ordered on my behalf, but I haven't gotten any word on if/when it will ship. Order placed 11/03/09 I believe. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted November 30, 2009 Author Share Posted November 30, 2009 What's the shipping status on the 2600 mods? One was ordered on my behalf, but I haven't gotten any word on if/when it will ship. Order placed 11/03/09 I believe. I have been turing them out in buches. Yours should be coming up. Parker Quote Link to comment Share on other sites More sharing options...
Carey85 Posted December 1, 2009 Share Posted December 1, 2009 I installed a Longhorn mod today that I've had lying around for a month or so. Got it in trade from a friend of mine who populated the bare board. The rest of the work was done by myself. Got pretty pissed as the first 2600 I tried the mod on was a broken system, serves me right for not testing it before the install . Ended up installing it in the system that I had my 8bitdoman mod in and I'm very pleased with the results, especially the faux-stereo sound which sounds nothing short of beautiful in Pitfall II. Only problem I've found and it might be as a result of being on an high definition display, is that on some games with a lot of flicker (Wizard of Wor) at certain times the sprites will have horizontal lines through them during heavy flicker. I also noticed the same issue in the red shield around the Qotile in Yar's Revenge. I dunno if this is the mod pointing out weaknesses in the system, a result of usage on a high definition screen, or the fact that I used a Rev. 14 4 switch board for the mod. I've heard that the best results are obtained with a 6 switch system but I can't bring myself to sacrifice one for the sake of my own vanity Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 1, 2009 Author Share Posted December 1, 2009 Only problem I've found and it might be as a result of being on an high definition display, is that on some games with a lot of flicker (Wizard of Wor) at certain times the sprites will have horizontal lines through them during heavy flicker. I also noticed the same issue in the red shield around the Qotile in Yar's Revenge. I dunno if this is the mod pointing out weaknesses in the system, a result of usage on a high definition screen, or the fact that I used a Rev. 14 4 switch board for the mod. I've heard that the best results are obtained with a 6 switch system but I can't bring myself to sacrifice one for the sake of my own vanity Its a limitation of the Atari. The mod unfortunately shows some of the programmers tricks sometimes. Quote Link to comment Share on other sites More sharing options...
Carey85 Posted December 1, 2009 Share Posted December 1, 2009 Yeah, that's what I figured. I deduced that it was a result of creative usage of bankswitching or something of the like. I'm very happy with the result, though. Thanks for your hard work. Want to buy an 8bitdomain 4 switch kit ? Quote Link to comment Share on other sites More sharing options...
Kenny_McCormic Posted December 1, 2009 Share Posted December 1, 2009 Will I still have RF with the Longhorn mod? Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 1, 2009 Author Share Posted December 1, 2009 Will I still have RF with the Longhorn mod? No but you can use S-Video and Composite at the same time. Quote Link to comment Share on other sites More sharing options...
Kenny_McCormic Posted December 1, 2009 Share Posted December 1, 2009 What if I did not lift the 4 pins on the TIA, what would happen then? Also, how does the mod interact with the VLBANK pin? I need to learn about the VBLANK pin for a pause project I have been thinking about. Keep in mind you are talking to someone who runs dial up every now and then just to do it. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 1, 2009 Author Share Posted December 1, 2009 What if I did not lift the 4 pins on the TIA, what would happen then? Also, how does the mod interact with the VLBANK pin? I need to learn about the VBLANK pin for a pause project I have been thinking about. Keep in mind you are talking to someone who runs dial up every now and then just to do it. If you don't lift pins 12 and 13 then you will not get stero sound. Not lifting pins 6 and 9 could cause some interference on the chroma signal. The mod just mixes the Blank signal into the luma signal. Which seems to help remove the vertical lines on LCD screens. Blank just signals the end of the screen or blacker than black if I remember correctly. Quote Link to comment Share on other sites More sharing options...
Kenny_McCormic Posted December 1, 2009 Share Posted December 1, 2009 Do you know when Blank is high/low? I'm thinking up a pause modification that would use it. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 1, 2009 Author Share Posted December 1, 2009 Do you know when Blank is high/low? I'm thinking up a pause modification that would use it. Nope. Any oscilloscope should show you tho. Quote Link to comment Share on other sites More sharing options...
Kenny_McCormic Posted December 1, 2009 Share Posted December 1, 2009 (edited) Unfortunately the only scope I have is a non functioning antique RCA WO-91B. Vacuum tubes, selectable between 1.5 and 4.5 MC. Edited December 1, 2009 by Kenny_McCormic Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 2, 2009 Author Share Posted December 2, 2009 Worked on the 7800 mod a bit today. Still working on the bleeding red. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 2, 2009 Author Share Posted December 2, 2009 (edited) Red Bleeding seems to be associated with the LUMA signal being slightly out of sync (like 38ns) with the Chroma. More testing needed before this is the final conclusion tho. Parker Edited December 2, 2009 by Longhorn Engineer Quote Link to comment Share on other sites More sharing options...
horseboy Posted December 2, 2009 Share Posted December 2, 2009 Worked on the 7800 mod a bit today. Still working on the bleeding red. :lust: :lust: Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 2, 2009 Author Share Posted December 2, 2009 Ok to do a really quick test this morning I pulled out my roll of magnet wire and used the entire spool to delay the chroma signal. I don't know how much wire is on the spool (close to 300-400ft left) so I don't know the delay but it was enough to lessen the bleeding to almost non existent. Now of course this is a very poor implementation of a delay but atleast it demonstrated what was the issue. Seems the NOR gate in the 7800 is really dam slow and is the prime reason for the serious bleeding. So im going to cut out the CD4050 and NOR chip and just run the mod straight off the MARIA chip and see what I get. Parker Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 2, 2009 Author Share Posted December 2, 2009 By the way for those that want to read up on luma/chroma delay and signals there is a nice article here. http://www.extron.com/company/article.aspx?id=svideoprimer Figure 3 is what is happening with the 7800 mod and what used to happen with the 2600 mod. Also this http://www.maxim-ic.com/appnotes.cfm/an_pk/1184 http://pdfserv.maxim-ic.com/en/an/AN3634.pdf Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 2, 2009 Author Share Posted December 2, 2009 (edited) Ok if I use some SOIC chips I can get the Luma delay to around 11ns which is within the spec needed. SN74LVC07AD - http://focus.ti.com/lit/ds/symlink/sn74lvc07a.pdf SN74F02DG4 - http://focus.ti.com/lit/ds/symlink/sn74f02.pdf No DIP chips have delays that are short enough. I think I am going to change the 2600 mod to use that SOIC chip as well just to cut down on the amount of different parts I have to buy. Also, I am planning on having the 7800 mod install just like the 8bit domain mod. Remove that one chip and solder in a socket. Anyone know where I can get the socket pins? Edited December 2, 2009 by Longhorn Engineer Quote Link to comment Share on other sites More sharing options...
horseboy Posted December 2, 2009 Share Posted December 2, 2009 You make me happy. Quote Link to comment Share on other sites More sharing options...
HARMIK Posted December 3, 2009 Share Posted December 3, 2009 I have an 8bitDomain mod for a 7800 if you need that for any ideas. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 3, 2009 Author Share Posted December 3, 2009 I don't need to rip off 8bit domain. That's taking the easy way out. I ordered the parts so next week I will be able to test a full fledge 7800 mod. Then its off to 5200 and PAL land. Quote Link to comment Share on other sites More sharing options...
+batari Posted December 3, 2009 Share Posted December 3, 2009 Ok if I use some SOIC chips I can get the Luma delay to around 11ns which is within the spec needed. SN74LVC07AD - http://focus.ti.com/lit/ds/symlink/sn74lvc07a.pdf SN74F02DG4 - http://focus.ti.com/lit/ds/symlink/sn74f02.pdf No DIP chips have delays that are short enough. I think I am going to change the 2600 mod to use that SOIC chip as well just to cut down on the amount of different parts I have to buy. Also, I am planning on having the 7800 mod install just like the 8bit domain mod. Remove that one chip and solder in a socket. Anyone know where I can get the socket pins? There could simply be too much parasitic capacitance on the output of the gates. I might suspect those loose wires, or possibly fat PCB traces? Just a guess. Quote Link to comment Share on other sites More sharing options...
Longhorn Engineer Posted December 3, 2009 Author Share Posted December 3, 2009 Ok if I use some SOIC chips I can get the Luma delay to around 11ns which is within the spec needed. SN74LVC07AD - http://focus.ti.com/lit/ds/symlink/sn74lvc07a.pdf SN74F02DG4 - http://focus.ti.com/lit/ds/symlink/sn74f02.pdf No DIP chips have delays that are short enough. I think I am going to change the 2600 mod to use that SOIC chip as well just to cut down on the amount of different parts I have to buy. Also, I am planning on having the 7800 mod install just like the 8bit domain mod. Remove that one chip and solder in a socket. Anyone know where I can get the socket pins? There could simply be too much parasitic capacitance on the output of the gates. I might suspect those loose wires, or possibly fat PCB traces? Just a guess. Adding the long length of wire pretty much solved the issue. Its gate delay. 38ns is the total estimated gate delay of the circuit and anything over 20ns is fairly noticeable. Quote Link to comment Share on other sites More sharing options...
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