EvilDoctorShortCrust Posted January 20, 2013 Share Posted January 20, 2013 Can anyone please help with an atari 800xl I have which has no sound? I should straight away fill you in with where I am up to with it - Well I currently have 7 800XL's. 5 are working and 2 have issues. the one I'm trying to fix at the moment has no sound so I took the POKEY chip out and tried it in a working machine and we got sound ergo it's not the POKEY. I know someone is going to mention oscilliscopes at some point - no I don't have one. I don't mean to sound to direct but it'll just speed things up a bit to let everyone know now. I do have a DVM though and I'm not to bad with a soldering iron Also I am in PAL area and they do have the monitor output (I saw people mentioning this on a similar 600XL thread - I never realised NTSC consoles didn't have this) If anyone could advise I'd be really grateful Oh ps my other none runner has a black screen issue - tunes but does not display. I reckon I'll have a go at this machine when I've fixed the sound fault on the first one Quote Link to comment Share on other sites More sharing options...
BillC Posted January 20, 2013 Share Posted January 20, 2013 Can anyone please help with an atari 800xl I have which has no sound? I should straight away fill you in with where I am up to with it - Well I currently have 7 800XL's. 5 are working and 2 have issues. the one I'm trying to fix at the moment has no sound so I took the POKEY chip out and tried it in a working machine and we got sound ergo it's not the POKEY. I know someone is going to mention oscilliscopes at some point - no I don't have one. I don't mean to sound to direct but it'll just speed things up a bit to let everyone know now. I do have a DVM though and I'm not to bad with a soldering iron Also I am in PAL area and they do have the monitor output (I saw people mentioning this on a similar 600XL thread - I never realised NTSC consoles didn't have this) If anyone could advise I'd be really grateful Oh ps my other none runner has a black screen issue - tunes but does not display. I reckon I'll have a go at this machine when I've fixed the sound fault on the first one I don't know about the differences between NTSC/PAL systems, but I don't think there would be any significant difference in the audio circuit. The most likely cause I see for no audio is the LM358 op-amp, U1. The are also assorted resistors/capacitors in the circuit as well but these are less likely to have failed. 1 Quote Link to comment Share on other sites More sharing options...
EvilDoctorShortCrust Posted January 20, 2013 Author Share Posted January 20, 2013 Thanks, I'll pop that bad boy out tonight and give it a test in the socket one I use for such things. Hopefully the saga ends there but should that turn out to be good then any readings on the resistors/caps would be really helpful. Again thanks for the nudge in the right direction - really appreciate it Quote Link to comment Share on other sites More sharing options...
+orpheuswaking Posted January 20, 2013 Share Posted January 20, 2013 Just FYI, it is only the 600XL NTSC that omits the monitor port Quote Link to comment Share on other sites More sharing options...
EvilDoctorShortCrust Posted January 20, 2013 Author Share Posted January 20, 2013 UPDATE: Dropped chip from position U1 and tested in working board and we've still got sound so not that me thinks. Bill if you or anyone else has any readings which you believe I should test then I'd be really happy. As described above I do have a fully socketed, fully working system with which I can swap out chips. Resistors I'd need a bit of help with and if anyone can highlight which caps are most likely to be suspect then I can easily replace these. Please keep the ideas coming folks - I really want to crack this baby Quote Link to comment Share on other sites More sharing options...
BillC Posted January 21, 2013 Share Posted January 21, 2013 UPDATE: Dropped chip from position U1 and tested in working board and we've still got sound so not that me thinks. Bill if you or anyone else has any readings which you believe I should test then I'd be really happy. As described above I do have a fully socketed, fully working system with which I can swap out chips. Resistors I'd need a bit of help with and if anyone can highlight which caps are most likely to be suspect then I can easily replace these. Please keep the ideas coming folks - I really want to crack this baby I am attaching a ZIP file containing the Sobola 800XL schematics, this should help you with the troubleshooting. The sound circuit starts at the ANTIC on page 6, continues on page 8 with the LM358, and finishes with the connection to the monitor port on page 9. 800xl.zip Quote Link to comment Share on other sites More sharing options...
EvilDoctorShortCrust Posted January 21, 2013 Author Share Posted January 21, 2013 Cheers Bill, I have a good study of that Quote Link to comment Share on other sites More sharing options...
IronWorks Posted January 21, 2013 Share Posted January 21, 2013 One thing to check If they`ve not worked before and you are using the TV aerial connection is what pal version they are? Uk (pal I) uses a different audio carrier to most of the rest of europe (pal b/g). Unlikely but just a thought. Quote Link to comment Share on other sites More sharing options...
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