Waaahhhhhh Bank 0 won't record - Bank 1 is fine and MIDI is working

So I fixed my MIDI problem, (swapped the 6n138) added an on off switch and put in the 1000uf cap and put it all back together, but damn!~ NOW there's a new problem...prior to this everything but MIDI was working, but now Bank 0 wont record. 

I boot up see the proper lights, LED 2 blinks (which means empty bank?) so I push Record and LED 0 lights up which is correct and it shuts off when I stop recording  but LED2 keeps blinking all the time and there is no sample. 

If I switch to bank 1 everything records as it should. I can even play bank 2 with MIDI         8-) 

In addition the half time button now seems to do nothing if that's a clue

Where do I look? what do I do? ....nothing physically changed on the board except the cap swap , the on off switch is just a break in the + voltage (on or off)

Should I reload the firmware?  


  • just a guess, check if it works without the plastic. i only know the pink stuff from ESD packaging which means conductive. would be the easiest fix, almost too easy but who knows
  • Well the problem showed up before the plastic, I just did that to see if it made a diference ...I tested the outer shell of the cap and its non conductive, Ohms - infinity , but what the heck I'll try aga
  • If one of the banks doesn't work and you don't see it fill (that LED keeps blinking) then it's probably not getting the clock correctly at the input pin.  Bank 0 and Bank 1 have different input pins on the AVR.
    Make sure when you changed the opto you didn't accidentally mess with the CLK connections on the top edge of the board -- they're very close to the MIDI pins.
  • I will check that but I swapped the opto by pulling it out of the socket I put in so the "messing"was pretty minimal, 
  • you said   
    Bank 0 and Bank 1 have different input pins on the AVR. Make sure when you changed the opto you didn't accidentally mess with the CLK connections on the top edge of the board -- they're very close to the MIDI pins.

    SO on the chip pin 14 is MIDI in and the XTAL ins are pins 12 and 13...is that where you mean to look? are those the CLK connections at the top pf the board?  sorry for being so dense.
  • Or do you mean the B1_CLK inputs between CV and MIDI Out at the top of the board 

    I'll check there too 
  • OK so I went and looked at the connection at the top of  the board and its counter part on the I/O card and  (thanks to Todd's suggestion) I'm pretty sure I found a problem there (hopefully THE problem ) but do not have time tonight to fix it. Will report back tomorrow. 

    I will say this for a second time if you are going to use ribbon cable and choose to work with 28 gauge stranded you need to be VERY careful that there are no loose strands and and do not plan to manipulate your two boards very much after installation, i.e. make that the last thing you install....that thin stranded wire is fragile, tightly packed  and after about 3 or 4 bends it can break easily at the solder joint.  

    That is what I found, the 5th wire from the left had broken off and crossed its strands which is one of the CLK_CV pins. SO I will fix that tomorrow but solder sucking and removal in that tight area is going to test my skill set. If I had it to do over I would have used thicker gauge single strands and lived with the "ugliness" of that. - sigh 

    I hope to report that all is well tomorrow - wish me luck....
  • Yeah, my ribbon cable broke in a couple spots and I just went and redid it all with individual solid wires.
  • @everybody- agreed re: wire connections in general. I kicked myself during all 14 units I built that I didn't make those solder points into a single IDC connector.
  • Chapter 1 no midi.....fixed with new6n138
    Chapter 2 now midi works but bank 0 wouldn't record....fixed by
    removing ribbon cable agnd re wiring with separate higher gauge solid wire
    Chapter 3 bank 0 and 1 now both work great, but hold your breath....no midi, just a clicking sound on receipt of note on , even with 2 good samples and correct midi channels
    So tomorrow retrace the midi signal and see what's up.....
  • Chapter 3 update 
    Well I put the scope on again, 
    checked voltage at pin 14 with no MIDI = 5V check
    Checked pin 8 on the opto = 5Volts 
    so the chips have power

    I get MIDI signal at the  I/O board
    same for the two pins at top of main board 
    I get MIDI signal at Pin 2 and 3 of the opto, I get MIDI signal at the diode and both sides of resistor 5 
    so MIDI is getting to the opto 

    BUT , nothin comes out of pin 6 
    Pin 6 has continuity to pin 14  
    I even replaced the opto one more time
    I removed that pin 5 to 7 resistor on the opto in case I screwed that up, no difference 

    The frustrating thing to me was I;m pretty sure MIDI was working at one point unless I got bamboozled by the set up 

    Any ideas on what to do next, there are no bad solder spots on the opto socket


  • Is it stuck high or low?  The MIDI output may be shorted to VCC or ground.  Or it may be shorted to an adjacent pin on the MCU (or the opto, or at a via on the board).
    Are you seeing correct levels across the input diode?

    Incidentally, if it was shorted to VCC this could probably break the 6n138 which might explain your woes.
  • Is it stuck high or low? 

    is what stuck high or low, pin 6?, i.e 5 volts = high?
    something else? 
    Sorry for being Mr. clueless here

    The MIDI output may be shorted to VCC or ground.

    Are you referring to output of pin 6? or the MIDI OUT pins on the board. 

    Will check for shorts on MIDI out pins too, undoing that ribbon cable was almost messier than putting it in..  8-)     gotta love solder wick . 
Sign In or Register to comment.