gazjcollins Posted July 8, 2009 Share Posted July 8, 2009 Hi all, Just received my 7800 through the mail today. Hooked it up to the television using the standard coax cable and for the first minute or so, everything was great. However, the picture began to intermittently switch from black and white the back to colur then black and white again. This happens every half second or so - it is like clockwork. It seems to happen even more so when I have a 2600 cart plugged in. I have been reading up on some previous posts on here and one thing I suppose it could be is interference from Channel 5 (I am in the UK). Channel 5 transmits on channel 36 of the TV and - so does the 7800. Funnily enough, so does my old six-switcher 2600 and that was giving me grief picture-wise also. Opened up the 7800 to find "the tiny adjustable screw on the RF modulator" to adjust the Atari's freq as advised in a previous post but couldn't find it anywhere. Apart from doing a whole AV mod - does anybody have any suggestions? I would be very grateful for any help Quote Link to comment Share on other sites More sharing options...
mimo Posted July 8, 2009 Share Posted July 8, 2009 do you still have an antique called a video recorder? Try running it through that, it may help In my experience I have not found a decent PAL rf 7800 yet, the picture is godawful even at it's best. AV mod is the cheapest solution, or get a french system that has an RGB encoder built in Quote Link to comment Share on other sites More sharing options...
gazjcollins Posted July 9, 2009 Author Share Posted July 9, 2009 do you still have an antique called a video recorder? Try running it through that, it may helpIn my experience I have not found a decent PAL rf 7800 yet, the picture is godawful even at it's best. AV mod is the cheapest solution, or get a french system that has an RGB encoder built in Ha! Unfortunately do not have a video recorder. Having been having a look and think it may actually be best to do the AV mod after all. I've been in need of a weekend project anyway. Thanks for your advice. Quote Link to comment Share on other sites More sharing options...
gazjcollins Posted July 9, 2009 Author Share Posted July 9, 2009 Have been doing a bit of playing about to see if this was some kind of problem with my TV... For the first minute or so of the 7800 being on, the picture is fine but then it would begin to intermittently go b+w then to colour again. So I started playing around with the settings on the TV and adjusted the AFT (Auto Fine Tune) and voila! The 7800's picture stayed in colour - however, the graininess of the picture was now unbearable... Anyway - my diagnosis is that the 7800 transmits RF on channel 36 as it is switched on and the TV has no problem with this, however, as the 7800 warms up to operating temperature, it seems to slightly alter the RF of the 7800 to somewhere between channel 36 and 37 and the TV doesn't like this. So - at least I have a theory, but my problems still aren't solved..... Quote Link to comment Share on other sites More sharing options...
gazjcollins Posted July 10, 2009 Author Share Posted July 10, 2009 FIXED IT! Found the two little potentiometers on the board - the one toward the rear of the board affects the picture for 7800 games - the one below it alters the 2600 picture. Gave 'em both a tweek et voila! Decent enough picture. Marvelous! Quote Link to comment Share on other sites More sharing options...
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