Altec Lg-Format Driver Diaphragm Replacement Instructions

7127 N. W. Third Street
Oklahoma City, Oklahoma 73127
(405) 789-0221
ALTEC® 288A
through E, & 291A
Series H.F. Drivers
TM
D IA P H R A G M /V O IC E C O IL AS SE M B L Y R E P LA C E M E N T
F O R A LT EC L AN S IN G ® 2 88 , 2 9 0 , 2 9 1, & 2 9 9 S E R IE S
H . F . C O M P R E SS IO N D R IV E R S
ALTEC® 288K-L, 291K,
& 299A Series H.F.
Drivers
ALTEC® 288G-H,
& 291B Series H.F.
Drivers
ALTEC® 290A-E
Series H.F. Drivers
D IA P H R A G M /V O IC E C O IL A S SE M B L Y
R E PL AC E M E N T F O R A LT EC L AN S IN G ®
2 88 , 2 9 0 , 2 9 1, & 2 9 9 S E R IE S
H . F . C O M P R E SS IO N D R IV E R S
2. As appropriate to the installation, remove
driver loudspeaker and/or horn from
enclosure or mounting, and take removed
H.F. compression driver assembly to the
prepared work area.
The diaphragm and voice coil assembly in
H.F. compression drivers is extremely delicate
and must be handled with care. Prior to starting
the replacement procedure, select a work area
that is clean and free from iron dust or chips.
Cover the surface with a few layers of clean
paper. The area must be free from drafts to
prevent iron dust particles in the air from being
magnetically attracted to and lodged in the voice
coil gap of the H.F. compression driver. Replace
the diaphragm and voice coil assembly in
accordance with the following procedures.
3. Remove screws securing driver cover (see
Figure 1).
4. Carefully lift the cover from the driver and
access the interior, as shown in
Figure 1. For the Altec Model 290-series
drivers, note that there is a transformer
mounting plate which covers the
diaphragm/voice coil assembly.
5. For Models 288, 291, and 299,
disconnect the two leads from their
internal binding posts; set cover aside (see
Figure 1). For the Model 290, disconnect
the leads that are attached to the two large
internal binding posts, remove the four
screws that secure the transformer
mounting plate to the body of the driver,
then lift off the transformer cover plate.
Set aside.
1. For Models 288, 291, and 299, remove
leads from the external binding posts.
Note electrical phasing (polarity) as leads
are removed. For the Model 290 driver,
disconnect cable.
COVER
CA UT IO N! The diaph ragm is extre me ly
delica te. U se ca re to pre ven t dam age. A void
physical contact with diaphragm. Keep
screwdriver away, as strong magnetic field may
a ttr ac t s cr ew d riv er in to dia ph ra gm .
INTERNAL
BINDING POST
ALTEC® 290K-L Series
H.F. Drivers
CAUTION!
The diaphragm is extremely delicate. Use
care to prevent damage. Avoid physical
contact with diaphragm. Keep screwdriver
away, as strong magnetic field may attract
screwdriver into diaphragm.
6. Remove the six mounting screws that
secure the diaphragm/voice coil assembly
to the body of the driver. Carefully work
diaphragm and voice coil assembly free.
Remove assembly (see Figure 2).
7. Clean foreign material from voice coil gap
with a short strip of one-inch wide
masking tape. Fold tape back to form a
strip with adhesive exposed on both sides.
Insert edges of the folded tape into voice
coil gap to full depth, and wipe clean
completely around circular perimeter of
phasing plug and top plate (see Figure 3).
Repeat cleaning procedure several times
with fresh tape until tape is clean when
withdrawn. Visually inspect magnetic gap
to make sure that it is free from all foreign
matter; repeat cleaning procedure, as
required.
MOUNTING SCREW
(Typical of 6)
CLAMP RING
GASKET
Figure 1. Typical Altec® 288/291/299 Driver
with Cover Open
P L E A S E N O TE : Where eas y access to th e driver is
available, the replacement procedure may be
completed without removing the H.F.
compression driver loudspeaker and/or horn.
DIAPHRAGM/VOICE
COIL ASSEMBLY
Figure 2. Typical Altec® 288/291/299 Driver
with Diaphragm/Voice Coil Assembly
Installed
Figure 3. Cleaning The Voice Coil Gap
8. LOOSEN the securing screw of each of
the two adjustable dowel locating pins
until the pins move freely (see Figure 4).
vertical side of the top plate.
11. With the new diaphragm/voice coil
assembly fully inserted into position,
tighten the securing screws on the two
dowel locating pins. This correctly centers
the entire assembly.
PHASING PLUG
12. Carefully remove the diaphragm/voice
coil assembly.
13. Remove the spider shim from the voice
coil gap.
SECURING SCREW 14. Carefully reinstall the diaphragm/voice
coil assembly; and, using an aluminum or
DOWEL
LOCATING
stainless steel screwdriver, install the six
PIN
mounting screws removed in Step 6.
NOTE: If you are installing a new-style
diaphragm/voice coil assembly in your
older 288 or 291 Altec® driver, proceed
to Step 15 before you install any
mounting screws. Exercise caution when
accomplishing this procedure in order to
prevent damage to the diaphragm/voice
coil assembly. To make certain that the
voice coil does not bind in the gap, apply
uniform pressure to each screw, tightening
them in a diagonal pattern until the
mounting clamp is secure.
Figure 4. Adjustable Dowel Locating Pin
9. Insert the spider shim that was shipped
with the new diaphragm/voice coil into
the voice coil gap, as shown in Figure 5.
SPIDER SHIM
15. If the old diaphragm you replaced on your
Altec® 288 or 291 series driver utilized
screw terminals to attach the leads, you
will need a 288-291 Series Leadwire Kit
to convert your H.F. compression driver
to the new-style push-on terminals used
on all diaphragms manufactured since
1983. To replace the old spade-lug type
leads with the new, push-on leads
provided in the kit, follow these steps:
VOICE
COIL GAP
PHASING PLUG
Figure 5. Spider Shim Installed Into Voice
Coil Gap
10. Carefully place the new diaphragm/voice
coil assembly onto the dowel locating
pins. DO NOT install the diaphragm holddown screws at this time. The shim sets
the voice coil into the precise position
necessary for proper sound reproduction,
while the free locating pins move to
accommodate the slight adjustment
needed to properly align the entire
assembly. Use care to avoid damaging the
edge and sides of the voice coil while
inserting it into the voice coil gap - it can
get caught between the shim and the
A. For the old-style nickel plated screwdown terminals (used on all Altec®
Models 288A-E, and 291A series
drivers), open the binding post by
unscrewing its top, then insert a small
screwdriver into the opening where
the speaker wire usually goes. Using a
pair of small needlenose pliers, turn
the nut inside that secures the binding
post to the rear cover while applying
pressure with the screwdriver in the
opposite direction. Take care not to
damage the small fibre washers that
insulate the binding post from the rear
cover. Repeat this process for the
second binding post.
B. Install the new lead wires on your
Altec® driver by connecting the red
wire to the L2 external binding post,
and the black wire to the L1 external
binding post. Tighten the nuts
securely by using the method given
above in Section A.
PLEASE NOTE:
Be sure to align the eyelets of the lead wires
onto the binding posts so that they will be
parallel to the top plate of driver when the
cover is fastened down to it. If this is not
done, they might come in contact with the
metal surface of the driver and short out when
the cover is reinstalled.
C. Take the six mounting screws that
come with the 288-291 Series
Leadwire Kit and, using an aluminum
or stainless steel screwdriver, secure
the diaphragm/voice coil assembly to
the top plate of the H.F. driver.
Exercise caution when accomplishing
this procedure in order to prevent
damage to the diaphragm/voice coil
assembly. To make certain that the
voice coil does not bind in the gap,
apply uniform pressure to each screw,
tightening them in a diagonal pattern
until the mounting clamp is secure
D. Connect the push-on connector of the
red lead to the terminal marked “+” on
the diaphragm mounting ring, then
connect the push-on connector of the
black lead to the terminal marked “-”
on the diaphragm mounting ring. You
may now proceed to Step 17.
16. For Models 288, 292, and 299, connect
the push-on connector of the red lead to
the terminal marked “+” on the diaphragm
mounting ring, then connect the push-on
connector of the black lead to the terminal
marked “-” on the diaphragm mounting
ring.
17. Install cover of H.F. driver, securing it
with the screws removed in Step 3. For the
Model 290 drivers, position the
transformer/cover plate assembly onto the
driver with the four screws removed in
Step 5; then connect the cable wire leads
to the internal binding posts, with the
black wire to terminal L1, and the white
wire to terminal L2.
18. Return driver to service; connect external
leads to binding posts. Take care to
maintain electrical phasing (polarity) as
originally wired.
M A D E A N D P R I N T E D IN T H E U N I T E D ST A T E S O F A M E R I C A B Y -
712 7 N . W . Th ird S treet Ž Oklahoma C ity, Okla. 73127
Telephone: (405) 789-0221 Ž www .GreatPlainsAudio.com
Great Plains Audio is a trademark of Great Plains Audio, Inc.
Altec and Altec Lansing are registered trademarks of Altec Lansing Technologies, Inc.
TM
42-02-035036
10/06/03