MIDI-Thru problem ?

[tomg]

oops Paul says I got it backwards.....guess I need to look it up again
too!

Tom



> Hey Michael,  I know this sounds stupid but don't ground the thru 
> jack. The midi spec says to ground the midi in jack only. This makes 
> sure that the midi cables themselves do not create a ground loop. 
> 
> The truth is you don't really need to ground ether, the current loop 
> will work without it but you might run into problems on long cable 
> runs or radiate midi data into badly shielded neighbors. OTOH
> midi ground loops can be a real problem.
> 
> Tom
> 
> > Hello dear listmembers,
> > 
> > i am again here to pest you with my silly questions:
> > 
> > After some struggling with various embedded processors and much
> > help from you, i finally mamaged to biuld my first DIY MIDI device, a simple
> > MIDI note --> 16 Gates converter box.
> > It just works fine, but then i wanted to add a MIDI-Thru jack. So i looked at the
> > MIDI.org schematic at http://www.midi.org/images/midihw.gif
> > and added the output according to this.
> > My circuit ist here: http://www.takeonetech.de/midi.gif
> > 
> > OK, the inputs to my onboard CPU does work and recognizes all MIDI data
> > without problems, so i do think that there is no problem in the input stage - the
> > signals do also look fine when i look at them with a scope.
> > 
> > But MIDI gear hooked up at the MIDI-Thru connector receives only garbage
> > and erroneous data. After double-checking all parts, connectors and cables
> > and verifying that the data at the thru-connector looks to me absolutely the same
> > as the on as then in-connector, i am absolutely clueless.
> > 
> > Has anybody encountered such a problem yet ?
> > 
> > 
> > -Michael Buchstaller
>