strange...

[DJMaytag]

At 03:41 PM 6/19/96 +0100, john.. wrote:
>On Wed, 19 Jun 1996, DJMaytag wrote:
>
>> well, maybe things aren't all that complicated after all, with this 606 to
>> cr-8000 triggering situation. i was able to trigger some of the 8000's
>> sounds with the cymbal and hi-hat triggers on the 606. it seems like those
>> triggers act normally, but something different is going on with the other
>> triggers. i got the 606 BD to trigger the 8000's BD, but it wasn't very
>> loud. maybe it's not at the right voltage? i tapped the trigger from one end
>> of R63, BTW.
>
>Hi Mitch,
>	I can't remember: does the T606 use positive pulses to trigger 
>it's drum sounds? (I know that the CR8000 uses `negative logic' for it's 
>triggers - ie in the `off' state, the trigger voltage is at +5v, with 
>trigger pulses being short bursts of `0v')
>
>When I was building my MIDI-trigger circuit, I had to play around with 
>pulse stretching for some of the sounds - notably the bass drum...


well, i know we scoped the normal trigger outs, and those are "negative
logic" outputs (is there a more definitive term for what's happening with
these pulses? are the being pulled to ground like a moog s-trig?). but i
can't really tell what's going on inside just by looking at the schematics.
there's a small circuit right in between where the trigger for the sound and
the "common trigger" goes and the pulse input to the sound generator
(op-amp's for the BD, SD, LT and HT, and god know what else is going on in
front of the CY's and HH's).

below is the circuit i'm talking about, for the bass drum (this should help
out those of us without 606 schems handy)

     0-----------------0------------0
     |                 |            |               0-- to  "+15 G"
     |                 \            |               |
    common         R62 /            |               \
 -- trigger            \            0               /
    input              /           /                \
                       |         |<                 /
                       0---------|  Q15       C18   |
                       |         |\        0---||---0
                       /           \       |     +  |
                   R67 \            0     GND       |
                       /            |               \
                       \            /               /
 BD in from            |            \ R63       R51 \
 CPU (pin 19)          0            /               /     0--> to pin 3
  |                   /             \     C25       |     |
  |   R69           |/              0------||-------0-----0----0   IC 5
  0---/\/\--0-------| Q14           |        +      |          |
            |       |\              \               \          0--> to pin 5
            \         >             /               /
            /          0        R64 \           R65 \
        R68 \          |            /               /
            /          |            |               |
            |          |            |               |
           GND       GND           GND             GND

i know that there is some sort of pulse coming from the cpu for each
instrument, plus a "common trigger" that is put out every "step"
(corresponding to the 16 LED's on the bottom) that goes to each instrument
(i was told that this "common trigger is amplified each time there is an
accent on a particular step, with the depth of the amplification determined
by the accent knob - i was completely unaware of this not too long ago).

anyway, i don't know what's going on here, but i tried a couple different
things and none of them has worked so far.

i built exact copies of this circuit and took the triggers from before R69
and R62 and applied them to my copies. no dice.

i built an exact copy of the "normal" 606 tom triggers (using a quad
comparator, a couple of transistors and a few R's). this didn't work either.
i tried adding the circuit around Q20 (on the top left side of page 5) that
is feeding the common trigger inputs of that quad comp. that didn't do a
thing for me.

i tried just directly jumping points from the 606 to the 8000. it worked and
it didn't work. the BD trigger at point R69 didn't work (well, i got the
bass drum to trigger 2 times each "step" - not what i wanted though, but it
only triggered it once when i had a bass drum note programmed on that
particular step). i tried at the point where R63 and R64 intersect. that
worked but it didn't seem to work right, the 8000's kick was too low. maybe
the trigger at that point wasn't strong enough? or not enough/too much voltage?

i stopped using and triggering both the 606 and 8000's kick's for a sec and
tried to trigger other sounds with the other 606 triggers. whattya know? i
was able to trigger the 8000's cowbell, the handclaps, and the rimshot
accuratly using the 606's CY and HH triggers (maybe even the 8000's conga's
and HH's, but i don't remember exactly - it was late last night).

it seems as if the triggering is different for the CY's and HH's compared to
the other 606 triggers. i went directly before each resistor where the
trigger goes into (or the seven silver jumper pins to the left of the 2 CMOS
memory chips (ic's 7 and 8)) and i got the triggers to work for some of the
8000's sounds there, but still got two triggers for each step on the other
606 triggers (execpt for when there is a note programmed, then there's only
one - which is what i want, but how do i stop the other two triggers per
step!?!?)

jeez, i've written toooo much tonight. if i lost anyone, i apologize (i'm
lost too) ahead of time. if ya can help me out, or at least try anyway, let
me know.

thanx,
mitch

djmaytag at terracom.net

three things to remember about me:
1) i'm not a dj
2) i have no intentions of becoming a dj
3) i'm not a washer and dryer repairman either