New info added...

edit: erroneous info

I built the little-scale MIDI to Sync24 circuit located here and I'm running into a few issues when using the Arduino Duemilanove. The sketch loaded fine, so I'm thinking it's one of a few areas in my build. Overall it's what I need - 5pin MIDI to Sync24.

- I've noticed the circuit will not work when I ground the Arduino. If I remove the ground, I get a (very unstable) signal. Odd. It's being powered via USB, so perhaps there's a ground loop somewhere?

- Instead of the 4n28 (none available atm), I tested with both the 6n136 and 6n139 optocouplers, similar to the Arduinoboy circuit. Could this be cause for the unstable signal? Could resistor values possibly change this?

- The schematic called for caps on pins 8/9/10 but I did not see any in the actual photo of the circuit. Are these necessary, or just for protection? I did not include these.

I've built DIY MIDI interfaces for other machines and multiple Arduinoboys in the past, but I'm going on day #2 now. Any advice would be greatly appreciated.