Transducer Issues - QSC K.2 Series Service Manual

8.14 Transducer issues

There are many different types of failures for transducers in K.2 series loudspeakers. The most common issues found are
the following: spider becomes unglued from the frame, cone tears near the surround, burnt voice coil (because of an ampli-
fier module failure), and voice coil rubbing on edge of magnet. These are often manufacturing issues but they do not occur
very often.
Symptoms:
• Missing or intermittent high and/or low frequencies
• Distorted sound
Failure verification:
• Tears in cone or surround, glue application issue, magnet damage, or other obvious transducer failures
• Open circuit measured across the transducer's terminals (or at the molex connector)
• Can hear obvious distortion when powering the transducer with a sine-wave tone using a separate amplifier (not the
amplifier module).
Repair notes:
LF transducer
• The low frequency transducer can be replaced without removing the baffle.
• Verify the gasket is installed on the replacement transducer Spare part K.2 LF
transducers should come with the gasket pre-installed.
• Verify the orientation of the LF transducer is correct. The wire tabs should be at
the 2 o'clock position.
Important note: When refastening the low frequency transducer to the baffle,
tighten the screws in a crisscross pattern (Figure 8.14.1). Be careful to not
damage the surround on the replacement transducer when fastening screws.
The surround cannot be repaired except by replacing the entire driver...Again!
HF transducer
• To replace the high frequency transducer, the baffle must be removed.
• All K.2 Series models share the same HF transducer.
• A diaphragm replacement is available for the HF transducer. This is a cost-saving
alternative and is recommended.
• Note the wire color in the table below for each model.
Wire Color
Green
Green / black
Yellow
Yellow / black
White
White / black
• Before attaching the grille, do a quick test on the loudspeaker. Plug a low-distortion audio sine wave generator into a
1/4" or XLR input on the amplifier module. Gradually sweep the frequency from 20 Hz to 20 kHz. All frequencies should
be audible and free of distortion or rattling. You should notice the sound crossing over from the woofer to the horn at
about 2 kHz.
48
Connection
LF +
LF -
HF +
HF -
Front LED anode
Front LED cathode
Figure 8.14.1 - Use a crisscross pattern
when tightening LF transducer screws
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