HK Audio CDR 210 F - Manual (Page 99)

99
K 1
1 Routine Maintenance
and Service Checks
1.1 Fans in the Power Racks
and VX 2400
Regularly clean the fans in the PR 16 and the
VX 2400 power amp!
2 COHEDRA ® Compact
Replacement Parts
If at some point you require a part for the
HK AUDIO
® COHEDRA ® Compact system, please
use the names and part numbers listed in Table 1 to
order it!
Note:
• If your equipment requires service, please turn
to your HK AUDIO ® dealer or the HK AUDIO ®
distributor in your country. They stock the required
spare parts.
• In the event of a fault, always indicate the defective
device’s serial number. This way the HK AUDIO ®
service team can ascertain immediately if an
update is available for your product.
• Use only original HK AUDIO ® replacement spea-
kers and parts! Most of these have been developed
especially for HK AUDIO
® products and are not
available directly from speaker manufacturers!
3 Overview of Required
Tools
Just three tools are required to perform service work
on speakers - a 3-mm Allen (hexagonal socket) wrench,
a 4-mm Allen wrench and a Phillips (cross-headed)
screwdriver or power screwdriver (see Figure 3).
4 Replacing Loudspeakers
and Voice Coils
4.1 8" Midrange Speaker
Proceed as follows to replace an 8" speaker:
• Unfasten and remove the grille’s Phillips screws.
Remove the grille.
• Unfasten and remove the four hex head bolts
holding the compression chamber and remove it.
• Unfasten and remove the four hex head bolts
holding the 8" speaker in place (see Figure 6).
• Disconnect the speaker wires and remove the speaker.
When installing a replacement speaker, connect
speaker wires to the proper posts, ensuring that
the polarity is correct!
4.2 The 1" Driver’s Voice Coil
Caution:
Because COHEDRA
® voice coils are preselected,
their quality tolerances are narrower than those of
standard DE 160 voice coils. To make the most of
CohedraTM Compact mid/high cabinets’ perfor-
mance capability, always use HK Audio voice coils!
Proceed as follows to replace the voice coil:
• Remove the mid/high unit’s service panel (the
sheet metal cover on the left side). To do this,
unfasten the eight Phillips head screws.
• Remove the service panel from the housing.
• Unfasten the voice coil housing’s four hex head
bolts. Use a chamfered 3-mm wrench since the
bolts are not directly accessible! Disconnect the wires.
• Take the lid off the voice coil housing.
• The voice coil can now be replaced.
Important: Replace the voice coil in a clean working
environment only. Be sure to keep dust and dirt
out of the open driver. If despite your precautions
particles manage to get in, use a strip of adhesive
tape to remove them or carefully blow compressed
air into the back of the driver to whisk the particles
out. When installing the new voice coil, ensure it is
centered properly. Proceed as follows to check this:
Close the cover of the voice coil housing and re-
connect the cords (red = plus, black = minus).
Feed a sine wave signal with a frequency between
1000 Hz and 1500 Hz into the mid/high enclosure’s
input. Sweep through the frequency. If you hear
abrasive noises like crackling or scratching, the voice
coil is not centered properly. Reopen the voice coil
chassis and turn the voice coil a bit until the signal
is rendered cleanly!
Figure 1: The VX 2400’s air intake
Figure 2: The COHEDRA® Power Rack 16’s fan unit
Figure 4: CDR 108 C with grille and compression
chamber removed
Figure 5: Rear view of the CDR 108 C with service panel
removed
Figure 3: Required service tools