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15
INTERNAL MODIFICATIONS
WARNING: Voltages in this equipment are hazardous to
life. No user-serviceable parts inside. Refer all servicing
to qualified service personnel.
NOTE:
• Only make changes to jumpers (X) and resistors (R). The
circuit board contains holes where resistors are to be added.
• For Channel modifications, the first character of the refer-
ence designator indicates the channel number,(i.e., R1027
refers to a Channel 1 resistor, X2001 refers to a Channel 2
jumper, etc.). Modifications affecting the Master section are
preceded by a “9” (i.e., X9001).
• All Channel modifications in this section use Channel 1 as
an example.
DISASSEMBLING THE SCM410/SCM410E
To access the printed circuit board for internal modifications,
proceed as follows:
1. Remove the power cord from the ac power source.
2.Remove the knobs, retainer nuts, and washers from the
front panel, as shown in Figure 29.
KNOB ASSEMBLY AND DISASSEMBLY
FIGURE 29
3. Remove the four screws at each corner of the rear panel.
4.Remove the two screws at each bottom corner of the front
panel.
5.Slide the back panel and printed circuit board out from the
rear of the chassis.
CAUTION: When reassembling the SCM410, DO NOT
OVERTIGHTEN the knob retainer nuts.Damage to the inter-
nal components will result if too much force is used.
MODIFYING THE SCM410 FOR 220–240 VAC, 50/60 HZ OPERATION
As supplied, the SCM410 uses 100–120 Vac, 50/60 Hz power.
To modify if for use with 220–240 Vac, 50/60 Hz power, pro-
ceed as follows:
1.Disassemble the SCM410 according to the procedures in
the
Disassembling the SCM410/SCM410E
paragraph.
2.Locate Voltage Selector switch SW9001 adjacent to power
transformer T9000.
3.Using a screwdriver, turn the center rotor to the 230 position.
4.Locate Fuse F9000 and replace it with a T 50 mA L, 250 V,
time lag fuse for 220–240 Vac operation.
5.Replace the power cord with a cord rated for 220–240Vac
operation.
MODIFYING THE SCM410E FOR 100–120 VAC, 50/60 HZ OPERATION
As supplied, the SCM410E uses 220–240 Vac, 50/60 Hz pow-
er. To modify it for use with 100–120 Vac, 50/60 Hz power, pro-
ceed as follows:
1.Disassemble the SCM410E according to the procedures in
the
Disassembling the SCM410/SCM410E
paragraph.
2.Locate Voltage Selector switch SW9001 adjacent to power
transformer T9000.
3.Using a screwdriver, turn the center rotor to the 115 position.
4.Locate Fuse F9000 and replace it with a T 125 mA L, 250
Vac, time delay fuse for 100–120 Vac operation.
5.Replace the power cord with a cord rated for 100–120 Vac
operation.
INSERTING A 12 DB MIC PREAMPLIFIER PAD
A microphone preamplifier channel gain can be reduced by 12
dB. This may be desirable with high-output microphones.
Procedure:
1. Short jumper X1000.
2. Remove resistor R1006.
DISABLING PHANTOM POWER BY CHANNEL
To disable phantom power for a given microphone input chan-
nel, remove the resistor specified in the following table.
Channel Remove Resistor
1 R1005
2 R2005
3 R3005
4 R4005