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--- In tr-707@yahoogroups.com , "acousmatique" <acousmatique@y...>
wrote:

> This is my gradual project.
> I bought a DR110 off some d00d for a few dollars, it had some

problems. The

> edit screen was flaky, certain voice data blinking on and off. More

to my

> concern, the open hats, closed hats, and cymbals were not working.

Since all

> three of these sounds derive from a common source of filtered

digital noise, I

> poked around there. Noise chips worked, output all of the way...

Near the

> transistors where the brass envelopes are supposed to happen, I

narrowed it

> down to an electrolytic capacitor. It had been squezzed in a bad

way, which

> had pulled one of it's legs, and the solder pad, off of the board.

I repaired the

> trace with some fine wire, which I wrapped around the capacitor

lead, and

> thunderbirds are go! All drum voices work. But the display was

cracked, so it

> crubled off- too bad.
>
> I love the sounds of the DR110. The noise source is filtered in

just such a way

> for the brass timbres, which is explained in detail in the DR110

service notes.

> The claps, rimshot, kick, and snare are pure analog transistor

badness.

> Transistors are used to make analog envelopes for the hybrid brass

sounds,

> not unlike the voices in the TR-707. Kind of harsh, electro

sounding, and

> extremely moddable.
>
> Now, the 707 is my favorite "grid" style drum sequencer

interface. "X0X" at it's

> best.- but I have never like the drum samples in the unit. I guess

the toms are

> decent, but on the whole the sounds are lacking. Never played with

a 727, but

> I should. Great interface though!
>
> The DR110 is so small, that I can fit it's boards under the 707

circuits. What I

> am trying to do is extract triggers from the 707 envelope

circuitry, pretty

> straightforward. Use those triggers to fire the 110 sounds, run the

DR110

> output up to the drum volume sliders, and use toggle switches to

select 707 or

> 110 sounds. Since some of the sounds expect triggers with different

timing, in

> relation to each other (especially the handclaps), I think I will

include the cpu

> board as well as the voicing board. I wouldn't mind learning to use

a

> microcontroller for this, but neither have nor afford right now.
>
> I have tried using a circuit which I had built, which turns input

into +5v, 1ms

> pulses, to inject working triggers into the DR110. No success. I

know which

> transistors expect triggers from the onboard CPU, but they don't

fire voices

> when I trigger them manually. Since the triggers timing is ideally

arbitrated by

> the 110 cpu, I decided to try to trigger the CPU board. There are

bare traces

> on the board, which function as switches when the conductive rubber
> membranes close on them. These go through some diodes to the CPU. I

tried

> sending 5v pulses on those, but no dice. Lastly, I had tried using

a 4016 quad

> CMOS switch to use a trigger to close the connections between the

switches.

> Didn't quite work, apart from some random bursts.
>
> Next to try, when I have some time
> I have been reading that CMOS switches and what they are intended

to

> switch are supposed to be running from the same voltage. Ah. My

trigger

> circuit and the CMOS switch were on +15v, but the DR110 runs on 6v.
>
> I need to figure out whether or not the DR110 can run off of the

+5v provided

> by the 707 voltage regulator. Otherwise, on the trigger extracting

board, I

> might need to make a little 6v regulator.
>
> Since CMOS switches are sensitive, it seems I should probably

ground

> unused pins on the ic, and run wires which are short as possible,

perhaps

> even shielded. People typically use 4066 switches more often for

this sort of

> thing.
>
> If I can reliably get the switches to close in time with provided

triggers, then I

> can play the DR110 with just about any source! Since there are mods

I intend

> to do to the DR110 voices, I might just do an all-analog-outs

version of the

> 707, so I have panel room for the additional controls. Then I can

get another

> 707 down the line for grungy digital mods.
>
> Remember, "TR" supposedly represents "Transistor Rhythm" ! >;]P
> CJ