ApolloBoy Posted November 15, 2012 Share Posted November 15, 2012 Just thought I'd ask this about performing a component mod after looking at the datasheet for the TMS9928. Looking at said datasheet, it looks like all I need to get component video out of it are three 470 ohm resistors and three 15 pF caps all tied to ground, has anyone tried this method yet? I'd really like to be able to attempt this using the parts I have on hand right now. 1 Quote Link to comment Share on other sites More sharing options...
ten-four Posted November 15, 2012 Share Posted November 15, 2012 Hi ApolloBoy. I'm looking forward to see what you comes up with. I have experimented with this very issue, and it was not as simple as you want to try. I do not have this problem now a days, because I have the French CBS version. The French version is born with RGB out. (Euro connector - Scart - EIA multiconnector). Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted November 15, 2012 Share Posted November 15, 2012 You need to check out this thread. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted November 15, 2012 Author Share Posted November 15, 2012 You need to check out this thread. Not interested in buying a kit, I'd like to be able to use standard parts that I have on hand. The main reason why I ask is because I plan to eliminate the 12V and -5V rails in the system, which means I'll lose the AV mod I already have installed. Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted November 15, 2012 Share Posted November 15, 2012 Not interested in buying a kit, I'd like to be able to use standard parts that I have on hand. The main reason why I ask is because I plan to eliminate the 12V and -5V rails in the system, which means I'll lose the AV mod I already have installed. I too tried experimenting with simple and more complex setups and failed. I don't believe what you propose will work without further refinement (complexity). One issue I believe is the relatively loose tolerance on the RGB output from the TMS9928. I managed to get a nice crisp black and white image on my LCD TV with fixed resistors. However, because of the loose tolerance on the outputs you'll need some pots on those outputs to adjust them to get decent colours on your TV. The kit I linked to has pots on each output which appears to confirm my suspicions. Good luck with whatever you try and let us know how you get on. BTW - I have installed the kit in a CV and it works great - just a pain getting the pots set right so the colours look good. Quote Link to comment Share on other sites More sharing options...
+5-11under Posted November 16, 2012 Share Posted November 16, 2012 Answering the initial post... The problem is that the ColecoVision doesn't output component video. Close, but not exactly.You should get an output, but the blues will be too bright. If you turn down the blue, you'll also affect other colours, especially the yellows. My component mod kit accounts for this. If you're lucky or good, there may be a simpler way to accomplish the same goal. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted November 18, 2012 Author Share Posted November 18, 2012 I tried the setup as described in the TMS9928 datasheet, although I substituted the 15 pF caps for 30 pF ones. I did get the same problem that 5-11under described but if I turn down the brightness on my monitor it actually looks very good, albeit with some slight vertical lines. I think I might add some adjustment pots later so I don't have that issue, but overall I'm pleased that I have something that's at least mostly useable. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted December 4, 2012 Author Share Posted December 4, 2012 I just recently tried replacing the 470 ohm pulldown resistors with 1K pots acting as variable resistors and I didn't notice any difference; the pots just seem to act as on-off switches and I can't get any control over the R-Y or B-Y levels. I think I'm done messing around with this for now but I might revisit it and try different value pots. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted October 1, 2013 Author Share Posted October 1, 2013 This is strange, I recently picked up a new PVM to replace the one I was using before, and surprisingly it automatically adjusts the image so that black is actually black with my CV component mod and not dark blue. Kind of strange this is happening but a very pleasing development nonetheless. Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted October 1, 2013 Share Posted October 1, 2013 This is strange, I recently picked up a new PVM to replace the one I was using before, and surprisingly it automatically adjusts the image so that black is actually black with my CV component mod and not dark blue. Kind of strange this is happening but a very pleasing development nonetheless. What's a PVM? Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted October 1, 2013 Author Share Posted October 1, 2013 What's a PVM?It's a series of professional-quality monitors made by Sony. They usually have a variety of inputs including composite video, S-video, RGB and component. They're renowned for their excellent picture quality which is part of the reason why I have one (two actually!). Quote Link to comment Share on other sites More sharing options...
Ikrananka Posted October 1, 2013 Share Posted October 1, 2013 It's a series of professional-quality monitors made by Sony. They usually have a variety of inputs including composite video, S-video, RGB and component. They're renowned for their excellent picture quality which is part of the reason why I have one (two actually!). Thanks for the explanation. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted October 26, 2013 Author Share Posted October 26, 2013 (edited) Here's a request for anyone who had their CV modded for component by doubledown. I'd like to know what method he used, as I'd not only like to do some further tweaking to the circuit I have in my CV, but I'm also interested in modding my Sega SG-1000 II for component by switching out the TMS9918 for a TMS9928. As I stated before, the circuit I used works perfectly fine on my two new Sony PVMs, but it still has the color difference issue (with black being dark blue, etc.) on other TVs and monitors. I'd love to be able to use this on any TV, in case I decide to bring my CV or SG-1000 to a friend's place or something. Edited October 26, 2013 by ApolloBoy Quote Link to comment Share on other sites More sharing options...
+5-11under Posted October 27, 2013 Share Posted October 27, 2013 (edited) Here's a request for anyone who had their CV modded for component by doubledown. I'd like to know what method he used, as I'd not only like to do some further tweaking to the circuit I have in my CV, but I'm also interested in modding my Sega SG-1000 II for component by switching out the TMS9918 for a TMS9928. As I stated before, the circuit I used works perfectly fine on my two new Sony PVMs, but it still has the color difference issue (with black being dark blue, etc.) on other TVs and monitors. I'd love to be able to use this on any TV, in case I decide to bring my CV or SG-1000 to a friend's place or something. Doubledown used a more passive method when providing component video output. Many years back I asked how he did his component video mod, and he didn't really tell me anything more than that... The Zaxxon picture doesn't show yellow (edit: referring to the VGA one, because he's using a converter from component), but you can see how the other colours are skewed, so I'm guessing he's not doing anything to bring back the brightness of the yellows: http://atariage.com/forums/topic/130346-colecovision-video-upgrade-comparison-pictures/ Edited October 27, 2013 by 5-11under Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted October 27, 2013 Author Share Posted October 27, 2013 Sounds like he might have used a very similar method compared to what I have in my CV. Has anyone tried using a 1K ohm pulldown resistor on Y as opposed to 470? The CV seems to use that so I'm wondering if that would have any affect on the color difference issue. Quote Link to comment Share on other sites More sharing options...
ApolloBoy Posted October 28, 2013 Author Share Posted October 28, 2013 (edited) Well I've done a little experimenting and now it looks like the picture is very greenish, no matter what I do. I'm thinking the VDP is toast now... NM, I actually forgot to ground all my jacks! Works fine now! Edited October 28, 2013 by ApolloBoy Quote Link to comment Share on other sites More sharing options...
.thumb.jpg.74d5183f8a8eb1828ba82cf052d5cf85.jpg)
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.