Dauber Posted April 13, 2019 Share Posted April 13, 2019 So I have a modded 7800...the old school composite mod, RCA outs. After about ten seconds, the video gets very fuzzy for a couple of seconds, then goes out completely. Audio is still there though. I checked the solder connections, and the video connections are good and solid. But what else should I check? Could this be a voltage regulator issue? Someone else suggested checking the 7505, but....which chip is that??? The 7800 in question is, I believe, one of the last ones out of the factory - no expansion port or a cut-out for the port, if that helps... (Thankfully this is my backup 7800; my main one is still rock solid!) Quote Link to comment Share on other sites More sharing options...
+sixersfan105 Posted April 13, 2019 Share Posted April 13, 2019 Maybe capacitors? I'm not very 7800-repair savvy so I'm likely way off, but thought I'd chime in! Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted April 13, 2019 Share Posted April 13, 2019 So I have a modded 7800...the old school composite mod, RCA outs. After about ten seconds, the video gets very fuzzy for a couple of seconds, then goes out completely. Audio is still there though. I checked the solder connections, and the video connections are good and solid. But what else should I check? Could this be a voltage regulator issue? Someone else suggested checking the 7505, but....which chip is that??? The 7800 in question is, I believe, one of the last ones out of the factory - no expansion port or a cut-out for the port, if that helps... (Thankfully this is my backup 7800; my main one is still rock solid!) Does this 7800 still have RF intact? If so, hook it up that way and see if you get picture and sound and if it is semi stable. If not, then without knowing exactly which mod you have, I'm going to assume it to be the simple composite transistor mod, and that mean the transistor is bad. Not sure what they use but I'd imagine it is a 3904/3906 type. I think by 7505, they meant the 7805 voltage regulator. But if that were going out I'd think you loose audio in addition to the video. But I suppose it is possible for it to be dying and not provide enough current to the rest of the system that you might only have audio, but...I'm thinking this isn't the issue. This is the reason I like to try and keep the RF in place if possible is to provide another means to hook up a system to verify everything is good with the main guts in the event that some modification work seems to be having issues. Quote Link to comment Share on other sites More sharing options...
Dauber Posted April 15, 2019 Author Share Posted April 15, 2019 Well, I found out why the video was fizzling out: It's just the stupid TV in my hotel room. For whatever reason, it can't handle the 7800's output. I'm in Milwaukee for Midwest Gaming Classic, and I wanted to play some 7800 stuff in my room. My main 7800 was at the Pie Factory Podcast table at the vendor hall, but I had my backup with me. After the show was over on Sunday, I went back to my hotel room and plugged in my main (and confirmed working) 7800...same exact problem. Tried my own TV that I brought....success! 2 Quote Link to comment Share on other sites More sharing options...
+sramirez2008 Posted April 15, 2019 Share Posted April 15, 2019 Freaking hotel room TVs! Quote Link to comment Share on other sites More sharing options...
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