midi interface

I never built that one, but I see at least one error in the schematic. U1 has output pin 4 going to ground. Yikes! The *input* should be grounded, not the output. The board layout is ok, but if you were going by the schematic, that could be your problem. If you're noticing a toasty -- or even toasted -- U1, rewiring that piece of it should fix it.

Otherwise, the schematic seems to be ok, after a 90 second skim.

pin4 of u1 isnt grounded. i did build it using their board layout and there pin4 isn´t grounded. anyway thx.

Well, since the board layout seems to be ok, then there are only a couple of possibilities:

1) You've got one or more dead components.

2) There's a wiring/installation error. Double-check your work carefully. Look for the usual suspects, like backwards-polarity diodes, incorrect polarities for electrolytic capacitors, chips upside-down, cold solder joints, solder blobs that short adjacent traces, etc. Use a voltmeter to verify that power is where it's supposed to be. Feel if any components are hot (none should even be warm in this low-power circuit)