Mod Nexus Series User manual

Seismic Shift JFET Boost
SEISMIC SHIFT
SEISMIC SHIFT
Copyright © 2021 by modelectronics.com
The Seismic Shift is a JFET boost based on one of the earliest effects to ever be
used on stage. This pedal adds subtle color to a guitar's sound while
maintaining the natural tone of the guitar. It packs a serious punch that can cut
through any mix when soloing or whenever some extra “umph” is required. The
Seismic Shift pairs nicely with amps and other pedals. Place it ahead of tubes,
preamps, overdrives, distortions, and fuzz pedals to shift your gear onto a new
level.
The Seismic Shift pedal kit is the introduction to the Nexus Series from Mod
Electronics. This series features a PCB base rather than the Mod Electronics’
traditional point-to-point wiring kits to offer builders an even wider variety of
effects to build. The Seismic Shift kit is designed for all skill sets and is the
perfect first build for those unfamiliar with PCB construction.
The pedal operates on both 9VDC and 18VDC. A center negative power supply
is required for use (not included w/ kit). There is no battery connection. When
using 9VDC the pedal draws 8mA. When using 18VDC the pedal draws 16mA.
The enclosure size is a standard 1590B (4.4" x 2.4" x 1.2").

Table of Contents
Seismic Shift JFET Boost 1
Notes on PCB Construction
Parts Lists
PCB BOM's
Applying The Sticker
Main PCB Construction
3PDT PCB Construction and Enclosure Parts
Calibration
Schematic
2
3-4
5
6
7-9
10-13
14
15
Section Page
Required Tools
Adjustable Wrench
Cutters
Lead Formers
Needlenose Pliers
Phillips Head Screwdriver
Ruler
Small Flat Head Screwdriver
Solder
Soldering Iron
Wire Stripper
Xacto Knife of Similar Cutting Tool
Optional Recommended Tools
Anti Static Wrist Strap
Desoldering Braid
Desoldering Pump
Helping Hands
Multimeter
Oscilloscope
PCB Vise
Signal Generator
Tweezers
For a full-color digital copy of these instructions please visit https://www.modelectronics.com/

Notes on PCB Construction
Seismic Shift JFET Boost 2
Lead Spacing
This section is intended for those unfamiliar with or new to constructing circuit boards.
Components are made in two common mounting types, radial and axial. Radial
components feature leads that are parallel and oriented in the same direction
whereas the leads of axial components protrude from each end of the component
oriented in opposite directions.
These parts will have corresponding footprints on the PCB marked with text.
C_ designates a capacitor and R_ is used for resistors. The BOM (bill of materials)
will cover all of the designators. Each footprint has a specific spacing.
Footprints for the radial parts will match the spacing of that part but axial parts
require preparation to fit. For the resistors in this kit you can simply use your
finger to push the lead until it is perpendicular where the lead meets the part.
Other axial parts will have lead spacing that are referenced in the instructions.
Use a lead former tool on these parts.
Soldering
After inserting the PCB into its footprint make sure that the component is sitting
flush against the PCB. Hold it in place and bend the leads on the opposite side of
the PCB away from the component. This will keep the component flush to the PCB
when soldering.
Make sure your soldering iron is fully warmed up before soldering. Position the
tip of the iron so that it is touching both the solder pad of the PCB and the
lead of the component. Slowly feed solder onto
the pad. The solder should flow evenly across
the pad and will slope up onto the component
lead. You may need to move the end of the solder
strand around the pad to ensure that the pad is fully
coated in solder and that it is also bonding to the lead.
Repeat this process for each lead of the component then
use a pair of cutters to snip the lead directly above the peak
of the solder.
Ideally the solder will flow through the pad hole and a small
amount will reach the opposite side of the PCB. This can
take some practice to master and is not critical. Focus on
consistently achieving full coverage of the pad with slight
slopes surrounding the lead first.

R-N100
Main PCB Parts List
R-N100K
R-N22K
1MΩ1/4W Metal Film Resistor
P-Q1N5817
C-D100N-50
C-D100-3000
C-PEID047-100
C-PEID1-100
P-QPF5102
R-VT96Y-5K
R-VAV-B500K
100Ω1/4W Metal Film Resistor
100KΩ1/4W Metal Film Resistor
R-O1M
22KΩ1/4W Metal Film Resistor
1N5817 Schottky Diode
250uF Electrolytic Capacitor
100nF Film Capacitor
100pF Ceramic Capacitor
47nF Film Capacitor
100nF Ceramic Capacitor
50uF Electrolytic Capacitor
5KΩTrimmer, 3296Y
B500KΩ9mm PCB Mount Potentiometer
PF5102 JFET, N-Channel
C-ET50-50-MOD
C-ET250-25-MOD
Qty 1
Qty 1
Qty 2
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
Qty 1
K-902-BOARD Seismic Shift Main PCB Qty 1
Seismic Shift JFET Boost 3

P-L352
P-H501-L-BLK
R-N1K
Red 5mm Diffused LED
1KΩ1/4W Metal Film Resistor
Qty 1
Qty 1
Qty 1
P-L710-RED
P-K382B
W-RN-11
Black Skirted Knob with Arrow
Mono 1/4" Jack
Qty 1
Qty 2
Qty 1
S-W3024TC-BK-50 24AWG Stranded Top Coat Wire 3 ft
P-H1590BCE-BK Black 1590B Enclosure Qty 1
P-PC-3PDT-BOARD 3PDT PCB
Soft Click 3PDT Footswitch
Qty 1
3PDT PCB Parts List
Enclosure Parts Lists
Seismic Shift JFET Boost 4
Seismic Shift Sticker
K-902-LABEL Qty 1
Red LED Lens
P-JB-IN-U Low Profile DC Barrel Jack Qty 1