DU-RDT PTH Build Manual

Bill of Materials

Qty.Mfgr.PartDescription
1DU-RDT DIY PCB
1DU-RDT Front Panel
2AlphaSR1712F-01081P8T rotary switch
2Eagle450-4760D-shaft knob
1PanasonicESB-33133DPDT switch
1E-switchTACBLKswitch cap
1E-switchTL1105DF160Q13mm tactile switch
9QingPuPJ301M-123.5mm mono jack
9knurled nut
1NXP74HC7014Nhex buffer
274HC164N8-bit shift register
174HC74Ndual D-type flip flop
174HC86Nquad XOR
5LED, green 3mm
50.320" LED spacer
61N4148small-signal diode
52N3904NPN transistor
5220Ω resistor
101KΩ resistor
310KΩ resistor
4100KΩ resistor
50.1μF capacitor
12 x 8 0.1" pin header
5DIP-14 IC socket
2Kobiconn164-9008-EIDC socket 16-pin
1Amphenol191-2801-11628 AWG 16-cond. ribbon

DU-RDT Kit Parts

Our Mouser project cart has most of the necessary components.

Note that the rotary switches stocked at Mouser have a longer shaft than the ones shipped with the kit; this can be fixed with a Dremel, since they will be covered with knobs anyway.

The 74HC7014N buffer in DIP has been obsolete for some time, and as of 2017 is becoming difficult to acquire. No drop-in replacement appears to exist. An alternative is to purchase the 74HC7014D in SOIC, and use a SOIC-14 to DIP-14 adapter. If you are not comfortable with a small amount of SMT soldering, or simply want the convenience, an adapter with pre-soldered IC can be ordered from Proto Advantage using Digikey part number 1727-6342-1-ND.

Build Procedure

General Advice

Check that your kit contains all of the parts listed in the BOM above before starting. All components of the DU-RDT are through-hole parts, and the placement is largely obvious from the drill footprint and silkscreen. Pay attention to the resistor values and the orientations of the diodes, LEDs, and ICs. The soldering order is not critical; the suggested order tries to make it easy to solder some of the more tightly spaced components while adding the more fragile semiconductor components later in the process. Note that the 78L05 is optional, and should not be populated when using the 16-pin bus header.

Step 1: Eurorack bus header

The 16-pin Eurorack bus header is the only component soldered to the back of the PCB, as indicated by the silkscreen outline. Solder this header first, as shown. Make sure it is flush against the PCB.

du-rdt-step01

Optional: If you do not have a 5V rail on your Eurorack bus, you may use a 10-pin header, soldered to the bottom 5 pairs of pads, and add a 78L05 voltage regulator in TO-92 package (not supplied in the kit) where labeled.

Step 2: Register delay selector switches

Solder the two large 8-position rotary selector switches to their positions at the top-center of the PCB. The curved spring portion should be oriented upward. Solder the side tabs first, then the pins.

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Step 3: Pattern lock switch

Solder the 6-pin pushbutton switch to its position directly below the two selector switches. It has a locator peg that should fit the corresponding hole in the PCB to ensure correct orientation. Make sure it is flush against the PCB.

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Step 4: IC sockets

Solder all five 14-pin DIP sockets. Ensure that the notched end of the sockets are oriented according to the silkscreen, and that they are flush against the PCB.

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Step 5: Decoupling capacitors

Solder all five decoupling capacitors. Their orientation is not important.

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Step 6: Resistor identification

The next step is to begin soldering the resistors, so at this point, take a moment to gather, identify, and sort the resistors in the kit according to the following chart matching color bands to values.

resistor-220220Ω
resistor-1k1KΩ
resistor-10k10KΩ
resistor-100k100KΩ

Check the resistances with a multimeter if unsure.

Step 7: Resistors

All resistors are mounted vertically, with one lead curved in a U shape so that it is parallel to the other lead. The resistor body (i.e. the straight lead) will sit in the circle marked on the silkscreen. Make sure that the curved leads will not contact the inner surface of the panel! You can use one of the 3.5mm jacks as a guide: the top of the resistor lead should not protrude beyond the height of the black plastic.

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Step 8: Diodes

Solder all six 1N4148 diodes. They should be oriented such that the stripe on the diode aligns with the stripe on the silkscreen.

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Step 9: Tactile switch

Solder the 13mm tactile switch in the top left corner of the PCB. Its orientation is not important.

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Step 10: Input jacks

Solder the four input jacks along the left side of the PCB. Ensure that they are flush against the PCB.

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Step 11: LEDs

Insert the LEDs into their spacers and solder to the locations shown. Ensure that the long (positive) lead is oriented according to the + symbol on the silkscreen. When soldering, take care to keep the LEDs straight and vertical, and make sure there is snug contact between the PCB surface, spacer, and bottom surface of the LED body.

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Step 12: Transistors

Solder the five 2N3904 transistors to the locations shown, ensuring the orientation matches the silkscreen.

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Step 13: Output jacks

Solder the five output jacks along the right side of the PCB. Ensure that they are flush against the PCB.

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Step 14: IC seating

Insert each of the five ICs to the correct socket on the PCB (the part number visible on the silkscreen through the socket should match the part number on the IC). Ensure that the orientation is correct; the notched end or the end marked with a dot should be aligned with the notched end of the socket.

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Step 15: Front panel

Carefully place the front panel over the switches, jacks, and LEDs. Screw the supplied washer and nut onto each of the two rotary switches and tighten them down. Screw the supplied knurled nuts onto each of the 3.5mm jacks and tighten them down. Add the D-shaft knobs to the rotary switches and press down carefully until they are fully seated. Add the black switch cap to the pushbutton switch and press down until it snaps on fully.

du-rdt-smd-step09

Step 16: Power cable

Tightly crimp the IDC connectors to the ends of the ribbon cable as show in the image, ensuring that the key is facing inward, and that the arrow aligns with the red stripe. Fold the ribbon cable back over the top of the connector, and snap on the strain relief clip.

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