5
2.3 Connector and Pin Functions (See pcb layout on page 4 also)
PL6
–
Power Input
Pin
Function
Connection To
Comments
1
+ Ve supply
Red
9 Volts to 18 Volts DC
2
-Ve Supply
Black
PL8
–
Audio Input
Pin
Function
Connection To
Comments
1
Input Signal
Yellow
2
Signal Ground
Black
PL9
–
Audio Output
Pin
Function
Connection To
1
+Ve Speaker Drive
White
Do not short to Ground
2
-Ve Speaker Drive
Blue
Do not use as Ground
NOTE
S:
1.
While the Audio Input is referenced to ground, the audio output is balanced. It is therefore
imperative that the Speaker (-) connection is not grounded at all.
2.
When using this module with a headphone socket, place a 100 Ohm 3-Watt resistor between
the Speaker (-) ground and the socket Ring, while switching the Speaker (+) through the socket
Tip connections.
LED Overload Indicator
A Red LED indicator is provided on the Keyboard PCB to indicate that there is an Audio Overload or Fault
condition. There is also an overload LED on the main pcb.
LED Status Indicator
A Tri-colour LED is provided on the keyboard PCB indicates the various module modes
2.4 Controls
2.4.1 PCB
The level controls provide adjustment of the audio level through the module. The module is factory set
to give a gain of approx. 1 with an 8 Ohm input and 8 Ohm speaker on the Output. The level that is
heard in the speaker when the unit is unpowered should be the same level when the unit is powered
and the DSP is set to Off. Potentiometer VR2 is the adjustment for the audio throughput gain.
Potentiometer VR3 changes the volume of the audio indicator beeps which indicate the functions of the
module. The solder link across JP16, which is adjacent to this control may be removed to stop these
tones completely. Potentiometer VR1 allows adjustment of the Piezo sounder level (if fitted). This is
factory set for optimum level but may be adjusted to suit individual requirements when the module and
sounder are fitted within an enclosure.
