User Manual

9
INTERNAL MODIFICATIONS
NOTE: Remove AC power before opening the unit.
ABOUT PRINTED CIRCUIT BOARD MODIFICATIONS
A jumper is represented by “X” on the printed circuit •
board legend, a resistor is represented by an “R.”
Therstnumberinthereferencedesignatorindicatesthe•
channelnumber;i.e.,R1027referstoaChannel1resistor,
andX7216referstoaChannel7jumper,etc.
Components in the Master section are preceded by the •
number “9” (X901, etc.).
The circuit board contains holes where resistors are to be •
added.
Asingledropofsoldercanserveasajumperbetween•
adjacent jumper pads.
AllChannelmodicationsinthissectionuseChannel1•
as an example.
INSERTING A 15 dB MICROPHONE PREAMPLIFIER PAD
Each channel’s microphone preamplifier gain can be reduced by 15 dB.
This may be desirable with extremely high-output microphones.
Procedure:
To pad the gain of the MIC position
Remove surface mount resistor R1023.1.
Solder a 680 2. Ω resistor at jumper X112. For a greater gain
reduction, use a resistor with a value greater than 680 Ω. Use a
lesser value resistor for less reduction.
To pad the gain of the PHM (phantom) position:
Remove surface mount resistor R1026.1.
Solder a 1.5 k2. Ω resistor at jumper X110. This reduces gain by
8 dB. For a greater gain reduction, use a resistor with a value
greater than 1.5 kΩ. Use a lesser value resistor for less reduction
NOTE: To compensate for higher output condenser microphones,
the factory-set gain in the PHM position is 13 dB lower than the
gain in the MIC position.
Procedure:
Short jumper X901.1.
Remove resistors R900 and R909.2.
LINE-LEVEL OUTPUT TO MIC-LEVEL OUTPUT
The Master gain control can be disabled so it cannot be tampered with. The
following table indicates the resistor value to be used for the desired gain.
Master Section Gain Resistance
-6 dB
5.1 kΩ
0
10 kΩ
6 dB
20 kΩ
Procedure:
Remove resistor R9230.1.
Install new resistor at jumper X914.2.
DISABLE MASTER LEVEL CONTROL