jamesgillre Posted December 20, 2015 Share Posted December 20, 2015 Hi all, new around here - hope I am not breaking any rules but I have recently resurrected my brother in law's 7800 which had a few problems (as I think most 7800s do I have learned) I had to replace the power switch - which is now resolved I had to clean the inside of it out and I also chose to do an A/V Mod since the RF modulator seemed to be corroded - it wasn't putting out a good picture at all and no audio just white noise. He had no power supply, so I ordered a replacement one also. I should also point out this is a PAL - I model. Long story short, I did the A/V mod - and I am really pleased with the picture - brilliant and exactly what I hoped for, but there is no sound whatsoever. I am very limited in my atari knowledge and basically follow all the instructions for the mod which I bought off a seller (I can provide more details if required). I was wondering if anyone could shed some light on the lack of sound - I have spent about a week thinking about it, and retrying different things - then I came upon your forums. I have some pictures also I took of the board incase anyone notices anything, but the capacitors all look fine, there is 2 circular components in the centre that have a brown/gluey type substance maybe they are the problem, I am not sure what their function is or if it is normal. I would be really grateful for any input at all. Many thanks and sorry for the long post. Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 (edited) try add 47K resistor betwen R33 & R32 and then take audio from R33 you can remove RF modulator too dont touch potentiometers / brown glue is only to keep factory setting On picture you can see my COMPOSITE mod Edited December 20, 2015 by tdididit 1 Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 (edited) Thank you so much for this response, I will give it a shot. I should point out I am a complete rookie when it comes to modding - I just have basic soldering skills from school. So I should desolder the R33 and R32 join, insert 47k resistor in place bridging between R33 and R32 and then pull audio from R33. Can I get the resistor at a regular electronic store like maplin or will I need to order one? Like would this be ok? http://www.maplin.co.uk/p/metal-film-2w-47k-ohm-resistor-d47k Also, did you have to do the same thing for yours? I did wonder if the sound was working before when I tried the RF, it just seemed like white noise, would this be consistent with what you're thinking? Once again really really appreciate the help - I'm hoping to relive some atari moments with my brother in law! (Oh and yea I didn't remove the RF modulator yet, I didn't tidy it up as I was so disappointed the sound was not working and spent hours pulling my hair out) Edited December 20, 2015 by jamesgillre Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 Thank you so much for this response, I will give it a shot. I should point out I am a complete rookie when it comes to modding - I just have basic soldering skills from school. So I should desolder the R33 and R32 join, insert 47k resistor in place bridging between R33 and R32 and then pull audio from R33. Can I get the resistor at a regular electronic store like maplin or will I need to order one? Like would this be ok? http://www.maplin.co.uk/p/metal-film-2w-47k-ohm-resistor-d47k Also, did you have to do the same thing for yours? I did wonder if the sound was working before when I tried the RF, it just seemed like white noise, would this be consistent with what you're thinking? Once again really really appreciate the help - I'm hoping to relive some atari moments with my brother in law! buy any 47Kohm resistor. now you will not have sound on RF too bc you have removed R32 and R33 my audio out was soldered to R33 (right side) now I am using audio out from cartridge thats why you not see cable there. In recipient atari 7800 schematics - should be helpfull 7800.zip Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 Okay I will give it a shot. Yes I know RF is dead now anyway Do you think there is a good chance it will fix the audio? I am hoping beyond hope! Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 And don't worry Everybody was a rookie first I didnt get my skills from school too Here is a picture of PAL 7800 mainboard prepared for heavy hardware mod I just finished de-soldering work Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 Okay I will give it a shot. Yes I know RF is dead now anyway Do you think there is a good chance it will fix the audio? I am hoping beyond hope! Audio is not broken !!! you just unpluged it when you removed R32 resistor Regards 1 Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 Ok I ordered 2 47k ohm resistor to pick up in store - gotta go get them now, then I will try your suggestion and show you a picture and let you know how it goes! I hope it fixes the audio Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 (edited) Ok I ordered 2 47k ohm resistor to pick up in store - gotta go get them now, then I will try your suggestion and show you a picture and let you know how it goes! I hope it fixes the audio you need just one, check my first picture. you need connect R33 & R32 right pads with it (the two resistors you have removed) , then your audio output will be at right pad of R33 keep my fingers crossed Edited December 20, 2015 by tdididit Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 Oh yes I know, I study your picture, I am getting 2 just in case I make a mistake with the first one! 1 Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 Just got done with that, still no joy - heres the picture. Still no audio at all.... perhaps I should try taking the audio direct instead of through the mod chip? Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 Just got done with that, still no joy - heres the picture. Still no audio at all.... perhaps I should try taking the audio direct instead of through the mod chip? 12414261_10153801763566624_1076188014_o.jpg Audio signal should be on R33 right pad, try to connect it direct to output plug Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 Audio signal should be on R33 right pad, try to connect it direct to output plug Do I remove the resistor or leave it in place? and do I need to join the r32 and r33 pads? Quote Link to comment Share on other sites More sharing options...
tdididit Posted December 20, 2015 Share Posted December 20, 2015 Do I remove the resistor or leave it in place? and do I need to join the r32 and r33 pads? resistor stay on place, and please, short those naked cables. it will make a shortcut Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 20, 2015 Author Share Posted December 20, 2015 (edited) resistor stay on place, and please, short those naked cables. it will make a shortcut Still no audio at all after connecting it directly onto pad beside resistor at r33 Edited December 20, 2015 by jamesgillre Quote Link to comment Share on other sites More sharing options...
jamesgillre Posted December 21, 2015 Author Share Posted December 21, 2015 Just got the sound working to anyone that was following this and thanks to tidididit's help ! 2 Quote Link to comment Share on other sites More sharing options...
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