The usual suspect is a faulty optocoupler (6N138).
Perhaps this is not installed, or there are bad joints there.
i.e. The PIC sends the upload requests, therefore “MIDI Out” is working. In the normal case, it would receive the upload packets and reply with acknowledgement messages. If the PICs don’t receive the packet, then they don’t reply. Therefore, the most likely problem is a fault in receiving MIDI, which is probably the optocoupler or something else related to it, the resistors connected to the optocoupler.
You might want to check the following components are correct and have good joints and connectivity:
D1 (check orientation!), R5, R11 (near optocoupler), R6_CORE1, R6_CORE2, R6_CORE3, R6_CORE4 (under PICs).
Refer to this, part labels on PCB will be obscured:
http://www.mb6582.org/plans/MB-6582_Base_PCB_Color.pdf
Checked all of these components, everything appears fine
MIDI Troubleshooting tests-
TEST CORE1: bought from Smash, so should be rtg
TEST CORE2: n/a
TEST CORE3: visually all looks alright
TEST CORE4: all check out
TEST CORE5: all check out
TEST CORE6: all good
TEST CORE7: ok
TEST CORE8: ok
TEST CORE9: ok
TEST CORE10: Hmm, so this wasn’t expected… When I used my Lexicon Lambda as my MIDI interface the situation outlined in above messages occured. When using my Novation Remote (NOT a Remote SL, which is blacklisted) I received an endless series of upload requests as outlined in this section of the troubleshooting guide. However, I tried to trace this signal path and check for any accidental solder bridges etc and didn’t find anything.
TEST IN1A: ok
TEST IN1B: ok
TEST IN2: ok
TEST IN3: led lights, can’t get it to flicker when sending a series of midi messages, perhaps just not enough of an effect for me to notice
TEST IN4: led lights
TEST IN5: LED flickers ever so subtly
TEST IN6: LED stays lit no matter what!
TEST IN7: no voltage measured from the test, whether switch open or closed. I tested 2 different 6n138’s as I had one from when I initially tried a year or so back to build a midibox sid using the standard modular pcb’s (not a mb6582) and had similar issues with my core. The optocoupler ripped from there reacted the same way as the one I received with the kit.
TEST INOUT1: not receiving any data back into the input
TEST PC1: ok
TEST PC2: ok
Even trying w/ 2 octocouplers I received the same results. Is this just a case of 2 faulty optocouplers? I’ve seen the messages that have said “when all else fails, its the optocoupler” and I just sent in a Fatman only to find out the optocoupler was faulty!!! OPTOCOUPLER! I WILL DESTROY YOU!!!

Yeh, is that what this all means?