[sdiy] Weird JX3P midi behavior

Tue Nov 27 19:37:46 CET 2012

Another interesting test - I connected the midi out to the midi
monitor only. Midi in was connected to the out of my Korg DW8000.
Nothing happened when playing the korg as usual, however if i
connected the RXD pin on the jumper from the JX's midi board to the
TX- pin, it essentially looped the midi input to the midi output and
registered the proper messages on MIDI monitor.  It looks like the
Midi input circuitry is working fine. Perhaps the midi mode switching
isn't correct or its something on the main board.

On Tue, Nov 27, 2012 at 12:26 PM, Travis Thatcher <recompas at gmail.com> wrote:
> I get the led lighting on the RX pin on the midi board when i send
> notes from another controller. this would be the final output on that
> pcb before going to the main board - assuming the 7400 is gating
> correctly?  When the switch is in midi position i get the protect pin
> going high and rxmode going low. When in middle possition protect pin
> is high and rxmode is high and when in programmer position protect is
> low and rxmode is high.
>
> On Tue, Nov 27, 2012 at 12:11 PM, Pete Hartman <pete.hartman at gmail.com> wrote:
>> If MIDI thru is working (things coming in go back out) then the optocoupler
>> sounds fine (said without the schematic, but MIDI circuits don't vary much).
>> The 7400 (acting as a buffer I presume) could have a problem.  Usually the
>> thru uses the same buffer chip, but individual gates could have issues and
>> others be fine.  An LED (with resistor) test on whatever output of that is
>> supposed to be going further upstream could be useful.
>>
>>
>>
>> On Tue, Nov 27, 2012 at 11:48 AM, Travis Thatcher <recompas at gmail.com>
>> wrote:
>>>
>>> It is a stock JX. I agree that it is bizarre to see some clock
>>> commands but there is nothing else running on my system that could be
>>> creating that. Its also weird that while its getting the 2 appropriate
>>> note commands to play the note, they are both at velocity of 1,
>>> instead of something like 64 for note on an 0 for note off (like my
>>> sixtrak does).
>>>
>>> MIDI out does not double as MIDI thru, however MIDI thru does indeed
>>> work.  In the last test it was outputting the note message for the
>>> notes i was hitting.
>>>
>>> >>MIDI-In might be broken if one of the following components is dead on
>>> >> the MIDI-Board:
>>> 74LS00 -> is there an easy way to test if this is functioning correctly?
>>>
>>> Optocoupler PC900 -> the test with the LED on the RX pin on the main
>>> board would mean this is working correctly, right?
>>>
>>> Diode 1S2473 -> removed and tested fine
>>>
>>> Q1 Transistor 2SC945 -> I'll test and can probably just drop in a
>>> replacement to be sure
>>>
>>> I'm wondering if it is not switching modes correctly? The test I did
>>> for the switch was to check if I could edit the sequencer.  Since this
>>> only works in programmer mode, as it should, I assumed the switch is
>>> correct.  Should I be testing the actual RX Mode pin and what should I
>>> look for?
>>>
>>> Thanks for walking me through all this guys!
>>> T
>>>
>>>
>>> On Tue, Nov 27, 2012 at 11:24 AM, Pete Hartman <pete.hartman at gmail.com>
>>> wrote:
>>> > Commonly there's a cap on the synth side of the MIDI in (as well as the
>>> > things Florian called out), is it ok?  Does your MIDI out double as MIDI
>>> > thru?  If so troubles with the input circuit could spill over into the
>>> > output side, otherwise the two shouldn't be connected.
>>> >
>>> > In that last test, did you actually hit D4, or did you hit some other
>>> > key,
>>> > and it's sending bad data generally rather than just for some things?  I
>>> > don't remember exactly where, but I've seen bad baud rates cause it to
>>> > look
>>> > like I was sending invalid MIDI bytes, and that isn't necessarily a
>>> > software
>>> > problem; Anything causing a drop in bits as well...  You might try
>>> > pressing
>>> > several side-by-side keys and see if the results vary any depending on
>>> > the
>>> > key.
>>> >
>>> > Just brainstorming...
>>> >
>>> > Pete
>>> >
>>> >
>>> > On Tue, Nov 27, 2012 at 10:25 AM, Travis Thatcher <recompas at gmail.com>
>>> > wrote:
>>> >>
>>> >> The synth does work perfectly but yes, the MIDI out appears to be
>>> >> corrupted and while that doesn't bother me as much, the MIDI in
>>> >> doesn't respond to note input at all.
>>> >>
>>> >> At first I thought it was only firing note on messages when I let up a
>>> >> key, but that was when I was just testing it controlling a soft synth,
>>> >> not actually looking at the midi stream.  This last test was done
>>> >> using midi monitor with no other midi input to my system and no other
>>> >> audio related programs running. Just midi out of jx to midi in on my
>>> >> Motu 828MKII.
>>> >>
>>> >> -T
>>> >>
>>> >> On Tue, Nov 27, 2012 at 9:10 AM, Florian Anwander
>>> >> <fanwander at mnet-online.de> wrote:
>>> >> > Am 27.11.2012 03:13, schrieb Adam Inglis:
>>> >> >
>>> >> >> Sounds like a problem reading the keyboard matrix,
>>> >> >
>>> >> > He would not be able to program the sequencer, if the kbd-matrix
>>> >> > would
>>> >> > be
>>> >> > read wrongly.
>>> >> >
>>> >> > As far as I understand Travis right. The synth itself works perfect,
>>> >> > but
>>> >> > the
>>> >> > MIDI-Out is corrupted.
>>> >> >
>>> >> > Just one question to Travis going back in the thread history:
>>> >> >
>>> >> >> 1. Midi out - note on events are only firing when you let up a key.
>>> >> >> No note off events are happening and nothing happens when you
>>> >> >> depress a key, only when you let off.
>>> >> > How did you recognize that? What was the receiver for the MIDI-Signal
>>> >> > coming
>>> >> > from the JX3P? How was the MIDI wiring set up?
>>> >> >
>>> >> >
>>> >> > Florian
>>> >> > --
>>> >> > http://fa.utfs.org/
>>> >> >
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>>> >>
>>> >>
>>> >>
>>> >> --
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>>>
>>>
>>>
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>>
>>
>
>
>
> --
> http://www.travisthatcher.com
> http://www.soundcloud.com/travisthatcher
> http://voiceofsaturn.blogspot.com

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