bad optocoupler?

[fadedpaper]

So I'm not getting any midi in to my core. I've tried all the tests on the troubleshooting page and failed mostly all of them. I'm sure it's not my midi interface since I get LEDs to light when I connect it straight to the midi cable.

I built the circuit to test the optocoupler (http://www.ucapps.de/howtodebug/mbhp_core_opto_test.gif) and I get +5V whether the switch is open or closed. Does this mean my optocoupler's bad? What causes an optocoupler to go anyway?

[Wilba]

I've had optocouplers fail on me, for no good reason.

One day it works, the next it just didn't. It's not like I fried it with 14V or something.

Optocouplers have a LED and phototransistor inside them... both of which could curl up and die due to a voltage spike I suppose, or an electrostatic discharge. That's my guess, I'm no expert.

Stick in another optocoupler and I bet it will all work.