Specifications

Sound from low-frequency speakers should be
clean and free from buzzes or rattles which may
indicate speaker failure. Replace any speakers
found defective. Be sure to
resolder discon-
nected leads and fasten all hardware securely
to avoid rattles.
High-Frequency Driver Replacement
To replace a high-frequency driver, follow these steps:
1. Disassemble the high-frequency driver assembly
as described in Speaker Servicing.
2. Unsolder leads from driver terminals.
3. Remove three 6-32
x 1 % in. screws securing
high-frequency drivers to gasket and mounting
plate of throat adapter assembly.
4. Replace driver diaphragm and voice coil assem-
bly as described in High-Frequency Driver Dia-
phragm and Coil Assembly Replacement.
5. Carefully place repaired or new high-frequency
driver in position over gasket and mounting
plate, taking care to line up holes in driver
over holes in gasket and mounting plate. Be
sure that driver terminals are in same position
as when removed.
6. Replace three 6-32
x 1 % in. screws, and tighten
high-frequency driver assembly in upper en-
closure compartment.
7. Resolder removed driver leads.
8. Reassemble upper rear panel to enclosure and
fasten securely to avoid rattles.
High-Frequency Driver Diaphragm and
Coil Assembly Replacement
The high-frequency driver is attached to the mount-
ing plate with three 6-32
X 1% in. screws. Refer to
Figure
N for further identification of driver components.
Replace the diaphragm and coil assembly in the
high-frequency driver as follows:
1. Disassemble high-frequency driver assembly
from enclosure as described in Speaker Servic-
ing above.
2. Unsolder leads connected to driver terminals.
3. Remove screws securing driver to mounting
plate.
CAUTION
Do not allow driver to drop when removed.
4. Prepare clean work area, free of drafts and
metallic dust and chips. Cover work area with
clean kraft paper or newspaper.
5. Place driver on work surface. With three 6-32
X 1% in. screws securing driver to mounting
plate previously removed, remove'phasing plug.
6. Remove diaphragm and coil assembly by lifting
upward. This is a snug fit and a gentle prying
force may be required.
7. Clean voice-coil gap in magnetic structure as
follows: Insert strip of masking tape into
voice-
coil gap with adhesive side outward. Draw tape
around gap several times to provide good
wiping action. Repeat process with new piece
of tape with adhesive side facing inward.
MOUNTING PLATE
ADAPTER ASSEMBLY
1
GASKET- ! CLEARANCE HOLES 161*
DIAPHRAGM AND 1
COlL ASSEMBLY
I
VOICE-COIL GAP
LOCATOR
PINS 131
CLEARANCE HOLES 131
MAGNETIC
STRUCTURE
I
FIGURE N.
DIAPHRAGM AND
COlL ASSEMBLY REPLACEMENT
CAUTION
The diaphragm and coil assembly is a deli-
cate part. Do not touch voice coil and bob-
bin, or allow it to come in contact with
work surface, tools, etc. If assembly is
placed on work surface, rest it on dia-
phragm with voice coil upward.
8. Assemble new diaphragm and coil assembly to
to magnetic structure with coil facing magnetic
structure. Locate three small holes in dia-
phragm and coil assembly over locator pins
in magnetic structure. Three large holes in
diaphragm and coil assembly will line up with
holes in magnetic structure.
9. Assemble driver and phasing plug to mounting
plate. Position mounting holes so that solder
terminals are outward and do not interfere with
adjacent drivers.
10. Replace three screws and tighten them securely
but do not over-tighten.
Resolder driver leads.
Reassemble the high-frequency driver into the
high-
frequency driver assembly and replace assembly in
speaker enclosure.
Overvoltage Attenuator Network
Threshold Adjustment
The protection circuitry of the SR108 high-frequency
driver array contains a 2000-ohm rheostat
(R10) which
may under certain conditions (component replace-
ment, extreme shock, etc.) require readjustment. This
may be accomplished as follows.
1. Turn rear-panel LOUDSPEAKER OPERATION
Switch
(Sl) to BlAMP position.