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5.3.V2 Controls

Control Terminal J2

J2 is a 8 position (only 7 used) , 0.1 inch pitch screw terminal connector located on right end of the LDR3x.V2 board as shown in the picture below.
ldr3x.v2 J2 & IR connections
J2 provides for the optional interfacing of three (3) control/status items:  the Encoder, the IR Module, and the Status LED.

The use of J2 is entirely optional provided the IR Module is mounted directly on to the V2 board and the V2 is controlled solely via a handheld remote.

The J2 Terminal interface points are shown in the following diagram and discussed below in more detail.

Label Type
IR D Input Infrared receiver pulse (required for remote)
+5V power Power for externally mounted IR Module
Gnd power Electrical ground
ST D Output Status LED (optional)
ES D Input Encode Switch (optional control input – on/off etc.)
Ea D Input Encoder leg A (volume control & input switching)
Eb D Input Encoder leg B (volume control & input switching)
n/c no connection – not used

ldr3x.v2 control wiring diagram

LDR3x IR Receiver module pins/wiring
IR Receiver | J2-IR

The V2 is supplied with a high performance 38 khz infrared receiver module (IR Module). The IR Module is supplied loose and not installed. The IR Module can be mounted on the V2 board in the location shown in the picture above. As a practical matter, it’s more likely that the IR Module will be located external  to the V2 board; typically behind an opening in the front panel of an enclosure. An externally mounted IR Module can be terminated either to J2, or alternatively, can also be conveniently terminated via mounting holes provided by a DM1 Display Module.

The picture to the right shows the IR Receiver and  its 3 pin connections. Incorrect wiring of the IR Receiver will immediately destroy it so be very deliberate when connecting the IR Module to the V2 board. If you locate the IR Receiver external to the LDR3x board, pin 1 must be connected to common ground (J2-Gnd), pin 2 must be connected to +5 volt power (J2-+5V) and pin 3 must be connected to J2-IR. Connecting wires to an externally mounted IR Module pins is an awkward exercise in soldering. We recommend using our DM1 Display Module which provides a mounting location for the IR Receiver on its circuit board.

Regardless of where you choose to locate the IR Receiver, it must have reasonable line-of-sight access to the handheld IR remote. The most common approach is to have the IR Receiver be “looking out” from the front panel of whatever enclosure you use to house the LDR3x.

Status LED | J2-ST

J2-ST is an output signal that when connected to an LED provides status information on the V2. The positive lead of the LED (the longer lead) connects to J2-ST which provides +5 V when the LED is turned on. The negative leg of the LED (the shorter lead) connects to common ground (J2-Gnd). In most cases you’ll want to place a resistor in series with the Status LED to limit current (and brightness) through the LED. We recommend a 10-30k resistor but this will ultimately depend on the specifications of your LED and your desired brightness.
The Status LED provides the following information

  • Multiple Brief Flashes:  Upon unit being powered up or turned on, or anytime the Enter key is pressed.
  • Steady On: Unit is on, is Un-Muted and is in normal Volume Adjust Mode (default).
  • Blinking Slowly: Unit is either Muted or at maximum Volume.
  • Blinking Rapidly:  Unit is in Balance Adjust Mode.
  • Blinking Very Rapidly:  Unit is in Remote Pairing Mode.
  • Brief Flash Every 2-3 Seconds:  Unit is off but is running auto-calibration.

Encoder Inputs | J2-ES, J2-Ea & J2-Eb

These 3 inputs are for interfacing the LDR3x.V2 with a rotary Encoder with integral push button switch. The Encoder switch is terminated to J2-ES.  J2-Ea and J2-Eb are for connecting the “A” and “B” legs of a rotary encoder. The common leg of the rotary encoder must be connected to electrical ground (J2-Gnd).

The LDR3x was designed and tested to work with the Alps EC11 series of encoders and more specifically the model EC11B15242AF although probably any of the EC11 encoders (or equivalent) will work.

Wiring Encoder Backwards:  If clockwise rotation of the encoder results in decreasing volume and counterclockwise rotation increases the volume, then simply swap the Ea and Eb inputs.

Pairing With Remote | J2-ES

There is one control function that can only be done via the Encode switch or some other switch connected via J2-ES. This control function involves pairing the V2 with the Apple Remote. Please refer to the preamp controls section on Apple Remote pairing.

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