1initial 2018

204 nov.2018failure in BOM and SchematicsLED-man
306 nov 2018BOM - review

please contact me if you want a assembled Module

The PCB and Panel is exclusively avaible from

The Schematics are only available for users who ordered the PCB or Module, contact me.

Module Description:

5U MOTM format  3U width (221,87mm x 132,97mm)

based on the Arp 4012 Idea

LED Slider

Resonance CV Vactrol based

easy to build

less wiring

skiff friendly

powder coated and silkscreened Aluminium panel

only 2 SMT components (led driver)

10/11mm leadspace (no bloody fingers like eurorack 7mm leadspace)

leadfree pcbs

MOTM Power header (-15V/15V)


3 Audio Inputs

3 CV Inputs

1 Resonance CV input

1 Output




BOM_potted_Module_4012_v1.2.xlsx one typo fixed  R2 = must be 470R instead 420R

BOM_potted_Module_4012_v1.3.xlsx  R2 must be 470R, R1 must 470R instead of 100K

(Double check with this file: 


There was a failure in old BOM and Schematics for the Controlpanel PCB, before 06.Nov.2018

R7 must be 3M3

R14 must be 150K

R29 to be doublechecked with JMLS in schematics 5K

c11 must be 22-47pf

R20 on controlboard is 100K - not listed in BOM.

Info for rare parts:

12N3958JFET N-Channel Dualrare part, ask Patrick aka DSL-man/LED-man
11k87Tempcorare part, ask Patrick aka DSL-man/LED-man


Short version:


start with the SMT Parts: 2 x LED driver diode on controlboard

assembly the controlboard, SW input pin 2 must be connected to SW output pin 2 (see picture)

mount all spacers for frontpanel and potted module, the 4x 12mm spacer are between controlboard and potted module, the other 4x 12mm spacer between potted pcb and DIYSYNTH cover pcb.

note: theres a LED above from the Vactrol, positive/negative is the same as the vactrol pinout marking, you can place it in the lower or upper position (its in parallel)

assembly the potted PCB:

place all resistors and 1N4148, solder this parts.

capacitors next, then IC socket, transistors.

The Ladder contains matched transistor pairs, match them to less 2mV VBE difference, or ask me for help.

test your 2N3958 tranistor and dont overheat them while soldering.


Note,  there´s one 2N3906 on left side of the tempco (from the pair the transistor on top)


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  1. Hi Patrick,

    After reviewing the BOM and comparing them with the PCB silkscreens,
    now I have a couple of questions.

    My PCB versions are: MOTM-VCF-REF1.1.8, 4012-BOARD5-REV1.1

    BOM_controboard4012 Questions

    1. C2, C3, C6, C7, C8, C9 (0.1 µF): which cap type is recommended?  MLCC?
    2. C10, C12 (1 µF): which cap type is recommended? 
    3. C11, C13: which values? which type?
    4. C14, C15: missing in BOM
    5. D3, D4: which diode? 1N4148?
    6. M1: what’s that?
    7. R1,R2,R3,R15,R34: (Bourns 3362) which resistance values?
    8. R38, R39: missing in BOM
    9. FILTER OUT: missing in BOM: female pin header?
    10. J1, J2: missing in BOM: female pin header?
    11. 6-pins +15/0/-14: missing in BOM: female pin header?
    12. ICs: silkscreen says, 2 ICs are LM301 (left and middle), 1 IC is LT1006Mj8 (right), but the BOM has 2x LT1006MJ8 and 1x LM301. is the silkscreen correct? or the BOM? in case of wrong silkscreen, a photo with corrections would be nice


    1. C-D1, C-D2, C-D3, C-D4: which diode? 1N4148 ok?
    2. C-C9: BOM says C0G, picture shows Film Cap, which is recommended?
    3. L1, L2: which value? regular MOTM ferrite beads?
    4. as all transistors are unlabelled on the silkscreen, a diagram would be nice, to know what is what

    Best regards and thanks,

    1. Thanks for your feedback Martin,

      i changed the BOM and added a silkscreen picture from the potted module.

      1. Thanks for the update,

        looks fine, except BOM_controboard4012 has R20 missing in BOM