Voltage check for IC2 inverted

MIDIbox SID
1

Howdy all!  After having been away from them for a couple years (long story), I sat down again with my kits to try to get a simple Core <-> SID making noise.  I’d bought the Smash kits for these two modules and managed to get them about 80% done then had to step away for a while.  So I’ve been poking at them again the past several days, and I’m astonished to discover that I have managed to make it all work… almost.

I have the core acting as expected;  it was one of the pre-burned MIOS PICs from the smash kits, so when I put power to it, it cheerily pops out the one little Sysex message.  And I’ve built the SID module, and wired them together with the single ribbon cable, (9v for the SID itself comes next), and per instructions, I go to check the IC voltage for the three sockets.  And what i get is:

IC1  25 -> 14: 5.2V

IC2  8 -> 16: -5.2V (negative, inverted)

IC3  8 -> 26: 5.2V

I’ve squinted at the schematics but I’m far too much of a newb to see what i could have done wrong to get just one of them inverted.

Have I missed some important piece of information during my long absence?  I have a vague uneasy feeling that I’m looking at instructions that are newer than the kits I have – my PCBs allege to be CORE_R4D and SID_R3A…  should I be checking with one of the "omg this is so deprecated but we keep it around for clueless slowpokes’ sets of instructions?

Thanks in advance for any thoughts on this.

2

You’re probably measuring the opposite way (hence the inverted value).

Perhaps you mounted IC2’s socket the wrong way around.

Check against SmashTV’s info page:

http://avishowtech.com/mbhp/mbhp_SIDR3a.html

3

Assuming you have mounted the socket the wrong way around, don’t bother desoldering it, just make a bigger notch in the other end, or a mark of some kind. I know this might be obvious to some, but we have been asked before whether it’s OK to leave an IC socket the wrong way around…  :wink:

4

Ha!  That’s exactly it.  I figured it might be something dumb on my part, but I wasn’t looking THAT dumb yet.  It hadn’t occured to me that the ICs might face different directions, all notches point north, right?

Thanks for the quick (and correct!) reply, off i go to see if I can get noise out of this thing tonight.  As usual, you guys kick ass.

5

The notches are in the picture on Smash’s page. They don’t all face the same direction!