NoahsMyBro Posted August 3, 2003 Share Posted August 3, 2003 Well, I've nearly finished modding my 5200 for composite A/V. This is probably the toughest hardware 'hack' I've done, and I must say I was pretty nervous when I went to test the system a few minutes ago. FWIW, the system is a 4-port. I didn't really give that much thought until I went to test things, and realized that I would still need to attach the switchbox in order to power the unit. D'oh! I haven't hooked up audio yet - the FAQ leaves the 2 1uF caps off of the parts list, and it's too late to pick one up. When I connected the video (I tied luma and chroma together at the end, just before the RCA jack), I got a sharp Black & White image on-screen. I noticed that on Jon Soper's page, he suggests just attaching sync & luma together in the middle of the job, and testing to see if you get a sharp B&W image. Does this suggest my chroma may not be securely connected? In the FAQ, there is a 1uf capacitor on the Chroma line. As I'm adding the chroma and luma together to use composite, should I NOT use that capacitor? For that matter, if I wired up the capacitor backward, would this be my result? I wasn't sure which leg was positive when I used the cap. Thanks, Steve Quote Link to comment Share on other sites More sharing options...
NoahsMyBro Posted August 4, 2003 Author Share Posted August 4, 2003 Why would I have a B&W picture? Should I have the 1uF cap on the chroma line if I am tying it together with the sync/luma for composite output? If I do have that cap on the wire, and it's backward, what will be the result? Thanks, Steve Quote Link to comment Share on other sites More sharing options...
Spirantho Posted August 4, 2003 Share Posted August 4, 2003 The result of a cap put on backwards is usually one dead cap! It actually depends on the type of capacitor, but if you're using an electrolytic it can explode a bit! Check the polarity - usually the longer leg is the cathode from what I remember, and will have a minus sign on it somewhere probably. I think you should be able to try it without a cap on that line at all, as it's there to smoothen the image, but don`t quote me on that. I *think* if you connect the chroma and sync together with no luma then you'll get a recognisable but very dark picture. Of course I`m not responsible for anything going wrong etc. (insert disclaimer bumpf here!) Quote Link to comment Share on other sites More sharing options...
jsoper Posted August 5, 2003 Share Posted August 5, 2003 Electrolytic caps can blow up when wired backwards, but I doubt these voltages will be high enough to do any harm. It is a good idea to block the DC component of the chroma when connecting it to luma, but again, not sure if it would be a big problem. One thing I would recommend, try connecting the chroma resistor into the base of the transistor, just like the luma resistors, you should get better sharpness. Are you sure you tapping into the right spot for chroma? It should be in color. Is the RF signal still color? And the 4-port switchbox can be removed, see website below. Quote Link to comment Share on other sites More sharing options...
NoahsMyBro Posted August 7, 2003 Author Share Posted August 7, 2003 I needed to get the dining room table cleared ASAP, so tonight I went ahead and toghtened up all of the connections and reassembled the 5200, in the desperate hopes that my B&Wness was due to a bad connection between the chroma signal and the rest of the circuit. No such luck. I've still got a B&W picture, although it is a very sharp picture. The sound is good too. I'll have to test the RF and get back to you guys on that. As for where I picked up Chroma - the bottom leg of the 2nd resistor from the right, on the row where all of the sync and luma signals are. I realize now I never checked to make sure the connection was good between my wire and the resistor on the motherboard. I'll have to double-check that too. Oh well. Hopefully I'll get to resume work on this over the weekend. Quote Link to comment Share on other sites More sharing options...
NoahsMyBro Posted August 11, 2003 Author Share Posted August 11, 2003 Well, I haven't had a chance to revisit this yet, but over the weekend somebody made me a suggestion that I wanted to run by you guys -- If the center post and outer ring on the video RCA socket are reversed, would/could that cause a black & white image? Quote Link to comment Share on other sites More sharing options...
sebastius Posted August 11, 2003 Share Posted August 11, 2003 Well, I haven't had a chance to revisit this yet, but over the weekend somebody made me a suggestion that I wanted to run by you guys -- If the center post and outer ring on the video RCA socket are reversed, would/could that cause a black & white image? No, it would just be 'no picture at all', since you'd be connecting the ground wire to the signal wire. But sure, you should try it. Quote Link to comment Share on other sites More sharing options...
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