Sir Radon . . . . .
My dealings with your situation was back in circa 1958 with an accompaniment sound effects electronics unit that a solo musician could use.
At that time it was all first generation transistors with NO I.C.'s yet being on the scene.
It had 3 sections just like yours does . . .the top white (pink) noise generation unit and the bottom, creating the specific different instrument voices of the unit.
They were blended to get the proper musical simulation effect if a heavy-medium-light "noise tail" was needed .
Your central unit uses a u-Processor brains to spit out triggers to all of the sound generation sections . . . . and repeat at required musical tempo timing .
In my case, this was all found to be using sequential transistor flip flop chains that outputted to hundreds of small signal diodes that steered into triggering a particular sound effect and then required further repeats with the music score.
One could individually trip an effect or there was a muuuuuulti pole switch that could select "programmed sequences" I remenmber FOXTROT-SAMBA-WALTZ-CHA_CHA-MARCH-TANGO-BOLERO-SHUFFLE-2BEAT-4BEAT, etc
Naturally that is what operation a solo musician would be choosing.
Instrument voices I remembered were sand block( thats where the white noise came in strong) . . . also on brushes.
Cymbal, bass drum, trap drum, conga drum,drumsticks,wood block were being other individual sounds.
The pots shown in the bottom board is where adjustment is need to trim in the "right"/ true instrument sound being created.
(BTW did your pots come selectively labeled and have paint drops sealing a setting, or did they give you resistance settings to set to ? )
They used schmitt trigger stages, critically tuned twin T circuits to be triggered, oscillators and blends and filters to create all of the distinct instrument sounds.
15 flip flop series arranged transistor oscillator pairs provided the sequential timing for the very longest tune sequence.
I had to reverse engineer and create a custom schematic and only made I copy and that was kept in the unit/ sent away.
(Any new fangled ZEE-ROCKS machine was being 25 miles away, burning 17cent gal gas.)
NOW . . . to help you . . . . I need mo' info than you have provided.
D-tronics, the site of your programmer /sequencer doesn't show me any equipment's internal photos.
Supply the source (kit) of your top noise generator and bottom instrument generator.
Initially evaluating I can see that your pink noise originates at top left corners 8 pin IC "PentaNoise" (proprietary techno gobbledy gook gibberish) generator
The next lower hex inverter pair are labeled as well as the powers 78L05 in upper top corner . . . is saying . . . me too . . .ME TOO . . .!
Then bottom . . . quasi . . . left corner is an op amp waiting to be identified.
Also, on it, track down pin 7 buss going right and later being labeled as [ ???Drive ???].
Also need confirmation of all weak showing TURQOISE Labels writing . . . one. . . .Decay is confirmed, others ? Also confirm another . . . as BLEND POT ?
On the bottom generator board confirm the ID of the left 8 pin IC, the transistor up at top above it as well as the central board located hex inverter, which may be the same one used on the other noise PCB.
We have to logically "consume" that all of the shown board flying wire interconnects had to come from the kits info.
(Dtronics . . . . .they say ? whaaaaaaaaat gives ?)
I second "The eyes" suggestion for additional filtering + shunting with .1ufd ceramic to the power supply connections at the kits boards.
Clicks may be due to direct DC connection between the noise generators output via the TURQ wire down to the bottom 8 pin IC's pin #2.
Try a .1 ufd paper or poly coupling /DC isolating cap inserted in series.
Thaaaaaaaaaasit . . . . . . 'til I heers back from you . . . . . .
73's de Edd . . . . .
I perused the cafes menu, thinking of trying something totally new, then asked the waitress for a quickie and she then HARD slapped me.
The older, and more worldly wise woman, sitting next to me, then said
"it's pronounced 'quiche', dear" . . . . . . '(key+shut)'
.