Internal Modifications - Shure SCM800 User Manual

NOTE: Remove AC power before opening the unit.
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.
LINE-LEVEL OUTPUT TO MIC-LEVEL OUTPUT
DISABLE MASTER LEVEL CONTROL
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
-6 dB
0
6 dB

INTERNAL MODIFICATIONS

Resistance
5.1 kΩ
10 kΩ
20 kΩ
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 first 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 modifications in this section use Channel 1
as an example.
Procedure:
To pad the gain of the MIC position
1. Remove surface mount resistor R1023.
2. Solder a 680 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:
1. Remove surface mount resistor R1026.
2. Solder a 1.5 k 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:
1. Short jumper X901.
2. Remove resistors R900 and R909.
Procedure:
1. Remove resistor R9230.
2. Install new resistor at jumper X914.
9