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FOR GUIDANCE
Diagnosis of low frequency driver failures resulting from
misuse:-
SYMPTOM
Charred voice coil
F u s e d , b r o k e n o r b l a c k e n e d l e a d o u t w i r e s
Voice coil out of gap
Coil rubbing
Broken frame or misaligned magnet assembly
Torn or punctured cone
Cone to coil joint failure
Suspension to coil/cone joint failure
Diagnosis of high frequency driver failures resulting
from misuse:-
SYMPTOM
Charred voice coil
Fused or broken leadout wires
Leadout to coil joint failure (solder)
Coil rubbing
Diaphragm cracked or pulverised
Misaligned magnet assembly
Diagnosis of manufacturing defects:-
DEFECT
Insufficient glue on:-
Cone to coil/suspension
Cone to surround
Surround to frame
Suspension to frame
Incomplete bonding of voice coil to
diaphragm or insufficient glue on rubber
surround to phase corrector joint
Dry solder joints on leadouts
Faulty welds at the voice coil terminations
on the coil former
Poorly assembled driver
PROBABLE CAUSE
Under powered amplifier clipping; Excessive peak amplifier
power; DC at amp output (amp failure)
Under powered amplifier clipping; Excessive peak amplifier
power; Excessive low frequency equalisation applied
Excessive peak amplifier power; Excessive low frequency
equalisation applied
Excessive continuous amplifier power resulting in separation of
coil former from cone or suspension; Coil delamination due to
excessive temperatures generated; Improper mounting of driver
resulting in deformation of frame; Dropping of cabinet resulting in
deformation of frame or shifted pole piece
Dropping of cabinet ; careless transportation
Excessive low frequency equalisation applied; Excessive peak
amplifier power; vandalism
Excessive low frequency equalisation applied
Excessive low frequency equalisation applied
PROBABLE CAUSE
Under powered amplifier clipping; Excessive peak amplifier
power; DC at amp output (amp failure)
Excessive amplifier power; connection to low frequency or
midrange amplifier in active system
Excessive amplifier power generating excessive temperatures
which melts solder >300°C
Excessive continuous amplifier power resulting in separation of
coil former; Coil delamination due to excessive temperatures
generated; Improper replacement of diaphragm assembly;
Dropping of cabinet resulting shifted pole piece
Excessive continuous amplifier power (often frequency related);
Under powered amplifier clipping; Connection to low frequency
or midrange amplifier in active system.
Dropping of cabinet ; careless transportation
TEST
Sine wave sweep
Sine wave sweep
DC resistance of voice coil termination
DC resistance of voice coil termination
Visual check
Sine wave sweep
Page 8
RESULT
Buzzing sounds due to separation of
defective joints
Buzzing sounds; Coil rubbing; Separation
of the coil from the diaphragm
Coil resistance greater than the rated
impedance, or open circuit
Coil resistance infinite or intermittent
Buzzing sounds; Loose parts; Coil
rubbing; foreign particles in magnetic gap
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