68kMLA Classic Interface
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| Click here to select a new forum. | | midi interface | Posted by: Bolle on 2007-05-07 06:43:53
hi guys!
does anybody of you did build such a thing and got it working:
http://www.usyd.edu.au/anaes/rpa/Loadsmanextras/Macmidi.html ?
I did it exactly as it´s described but it´s not worky.
Any help would be cool.
>bolle.
| Posted by: tomlee59 on 2007-05-07 12:19:17
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.
| Posted by: Bolle on 2007-05-07 12:38:43
pin4 of u1 isnt grounded. i did build it using their board layout and there pin4 isn´t grounded. anyway thx.
| Posted by: tomlee59 on 2007-05-07 14:52:20
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)
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