Mojotone FX LOOP v.2 Installation Manual

MOJOTONE FX LOOP VERSION 2 Installation Manual

How to Install the Mojotone FX Loop to Your Amplifier’s Chassis

Note: The following steps should be performed with the amplifier’s power cable unplugged. Follow all
electrical safety guidelines including discharging the amplifier’s capacitors. If you do not feel
confident to perform the following installation steps, let a qualified technician complete the work. If
you continue, you do so at your own risk.

Step 1: Line it Up Start by placing the template on the
amplifier chassis where the FX Loop will mount.
Ideally, since the signal will be sent through it, the FX
Loop should be placed as far away from the output as
possible. As a test, place the FX Loop in the location
where it will be installed, and make sure it does not
physically interfere with any other part of the amplifier.
Trace the insides of the holes on the template onto
the amplifier’s chassis using a marker, pen, or pencil.

Step 2: Drill it Out Drill the holes with either a step bit
or a regular metal cutting bit. Holes for the Send and
Return should be 7/16” in diameter. The hole for the
Bypass should be 3/16“ in diameter.

Step 3: Pop it In Insure that the FX Loop fits into the
holes and sits flush against the amplifier chassis.
Again, make sure the FX Loop’s components are clear
of obstruction from any other part of the amplifier.
Use the supplied nuts to secure the FX Loop to the
amplifier chassis. Note that mounting the FX Loop
component side up will position the Send jack on the
left and the Return jack on the right. The opposite will
result if the FX Loop is mounted component side
down.

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Wiring the Mojotone FX Loop into Your Amplifier

Step 1: What's on the Board Locate on the FX Loop component board the pads for the:

• Power Supply (B+)

• Ground (GND)

• Signal In (IN)

• Signal Out (OUT)

• Return Trimpot (RET TRIM)

• Send Mute (SEND)

Step 2: Hook it Up Solder a jumper wire from the low-power side of the amplifier’s power supply line,
which is usually after the final filtering capacitor and drop resistor, to the B+ pad on the FX Loop
component board. This voltage should not be under 150V or over 350V. Solder a wire from the
Ground (GND) pad on the FX Loop component board to a ground that produces the least amount of
hum noise. This will usually be the cathode ground for the stage before or after the insertion location
of the FX Loop.

Choose a point in the signal path to break and insert the FX Loop. The circuit is optimized for a point
just before the driver or phase inverter stage. In our JCM800 test circuit, the FX Loop either goes
between the treble and the master potentiometers, or just before the coupling capacitor into the
driver or phase inverter stage (see the schematics below). Solder wires to the Signal In (IN) and
Signal Out (OUT) pads on the FX Loop board, and run them to the area of the preamp where the signal
path will be broken. If this is on a PCB of which you do not want to cut traces, pull the coupling
capacitor from the board, and use the remaining holes for the installation. Remember, however, to
place the capacitor in line with the return lead of the FX Loop. If there are no DC considerations where
you are adding the FX Loop in the board, then it can be added without capacitors. If you experience
any sort of failure on install with the board, it is likely there was a bias consideration that is being
changed by the installation, and the circuit will need to be isolated with capacitors. Also, notice
ground pads above the send and return pads. These are added for convenience when using shielded
wire.

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