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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Thanks Pete.<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>On a lucky guess, I swapped the </span><span lang=EN-US>6N138 chip (no other component changes) and now working OK.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>I’ve been testing with two other MIDI sources:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>M-Audio FastTrack Ultra, 5V signal, no problems.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>M-Audio </span>MidiSport 2x4, 3.3V signal, no problems.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>And now <span lang=EN-US>M-Audio UNO</span>, 3.3V signal, no problems<o:p></o:p></p><p class=MsoNormal>…apart from that pesky ground issue<o:p></o:p></p><p class=MsoNormal>…and it doesn’t work with another sound module, but not investigated that very far yet<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>And thanks Harry for the adapter suggestion.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Al<o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> Pete Hartman <pete.hartman@gmail.com> <br><b>Sent:</b> 18 January 2023 17:45<br><b>To:</b> ShedSynth <shedsynth@gmail.com><br><b>Cc:</b> synth-diy@synth-diy.org<br><b>Subject:</b> Re: [sdiy] M-Audio Midisport Uno Wire to pin ?<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Wed, Jan 18, 2023 at 11:29 AM ShedSynth via Synth-diy <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'>An update: I have just bought a <span lang=EN-US>M-Audio Midisport UNO.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>And I’ve got myself a hum-loop:</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>The shell of the UNO’s USB-A plug has a connection to the shell of the MIDI OUT plug (but not to the shell of the MIDI IN plug).</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>And my home-built MIDI module (<a href="https://shedsynth.wordpress.com/midi/" target="_blank">https://shedsynth.wordpress.com/midi/</a>) has a metal DIN socket on the front panel which is grounded through the rack.</span><o:p></o:p></p></div></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>MIDI IN isn't supposed to be grounded, and I believe this is the reason. But you're saying it's not deliberately grounded, but going through the panel & the rack?<br><br>My quick/dirty idea is wrap a piece of electrical tape around the outside of that DIN socket so it doesn't make contact :-D<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm'><div><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>And it doesn’t seem to work with my MIDI module:</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>I measure the UNO’s MIDI OUT signal level at 3.3V, which doesn’t seem enough to light up my 6N138 with recommended 220R series resistor.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-US>The UNO variously does or doesn’t play through my other MIDI devices.</span><o:p></o:p></p></div></div></div></blockquote><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>What's the voltage drop across the 220R? This is supposed to be a 5mA current loop, so you should see about 1.1V. If you don't see that, I would suspect the UNO itself.<br><br>The "classic" driver circuit uses 5V to drive the loop, if you think that the lower voltage you're seeing on the UNO output is part of the problem, you may want to try dropping the 220R to 150R?<br><br>Do you have the connections to the DIN socket correct? I have always had to read the spec 3 times before I'm sure that I have them going the right way. A lot of the pictures of DIY circuits online either 1) don't label pins 4 & 5 and 2) don't make it clear whether it's showing a front view or rear view with respect to the DIN.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Like this one for example: <a href="https://i.stack.imgur.com/VmuRr.png">https://i.stack.imgur.com/VmuRr.png</a><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Hope this helps....<br><br>Pete<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></div></body></html>