I think I done Fried my CORE

[micah]

I built the SID + Core up this week, tested it, got everything working etc.

I turned it on yesterday and quickly looked up some some CC values for the controls, when I started smelling the heat. I unplugged it, I touched the 7805 and nearly burned my fingers off! I'm currently feeding the CORE 13V AC.

Well then I touched the PIC (I used my other hand for that) and nearly burnt my fingers off again! Then I tested it (in short intervals) and there was nothing. Not even a MIDI request. ???

So what are the possible culprits? A short? What should I look for and test, before I order another PIC and fry that too? I just don't understand what could have happened suddenly.

[moogah]

I'm currently feeding the CORE 13V AC.

.. ?  Whaddya mean by that?  In most cases I believe people have been using a DC wallwart power transformer to power their core. 

And, yes, be careful touching those regulators!  They can get *very* hot.  Search around a bit and you can find pics people have posted of their fingers with the regulators datecode and part number burnt into them!  Ouch!

It sounds like you've got a very wrong voltage going to the core, it should get warm at best, and if it's hot you need to remove it from the socket and test that it's getting only 5v, no higher.  If something is wrong there start troubleshooting the PSU section peice by peice.

[micah]

I'm still getting the correct voltages throughout the board.

HMM... Could my 7805 need replacing?

[micah]

I just supplied 9V AC to the CORE and the 7805 still got super-hot. Is this any kind of clue as to what could be wrong?

[th0mas]

Note that that touching chips isn't really a good idea - the oils on your skin stay on the chip, creating hot spots that will burn out the chip.

But it sounds like you might have already burnt your chip.

- question - what do have connected to the core? really bright LCD or something like that?

[micah]

No LCD. Just the SID module.

I am getting sporadic messages in my MIDI IN monitor (that's probably a good thing). Here's what it says

[FC] Stop

[F8] Timing Clock

[FF] System Reset

[FF] System Reset

[FC] Stop

[moogah]

Hmm.  I would replace the 7805 I guess, but I don't feel confident that is the problem.  If your core is sending messages I would think that it's not *dead*, although it is certianly possible if you burned yourself on it.  All I can really reccomend is to double back and check *everything*.  *three times*.  Literally get out every peice of documentaion about the core and check that you've got it correct.  It's a good idea to disconnect any other modules while testing if you havn't already.

I would reccomend a heatsink as well. ;)

[micah]

I troubleshot this thing all day. right now i have the "optimized" power supply going into the core only and I replaced the 7805. Still in the same boat though.

I tested pins 13-14 and the voltage is not what it should be. But I'm stuck about what to do now. I don't know what could be causing this. All of my solder joints are very neat and trimmed. Very frustrating  :-[

[moogah]

I've been in this situation countless times.  It's *always* been a simple mistake I made that was hard to spot because I was too close to the project.  Take a break for a couple days and then start again from the beginning.