Tech Guide - Technical Bulletins

Typical Failure Modes of Piezoelectric Audible Alarms

Component/Subsystem Failure Mode End Result Occurrence
Circuit Components (Resistors, Capacitors, Diodes, IC’s, etc.) Over-voltage by customer’s application Unit ceases working. Vast Majority of Returns
Transducer/Wire Solder Operation Not enough wire strands in solder joint Wire breaks after period of time & unit ceases sounding Rare
Physical Assembly Transducer wire pinched, adhesive/epoxy run down onto transducer, or RTV adhesive seal failure Intermittent operation Rare
Soldering Operation Incorrect Solder Temperature or Time Causing Cold Solder Joint Intermittent operation or unit ceases working after period of time Very Rare
Circuit Components Random Component Failure; Wrong Component Used; Missing Component Unit ceases working under normal operating conditions Very Rare
Transducer Wire Defect in Wire; Wire Strands Damaged in Production Wire breaks after period of time & unit ceases sounding Very Rare
Piezo Transducer Incorrect Polarization by Manufacturer; Glue Bonding Failure Sound volume level decreases over time. Exceedingly Rare


  1. Customer returns of Mallory audible alarms for failure to operate are very rare. Of the few parts returned each year, the vast majority of the root cause of failure is an overvoltage or voltage spike condition caused by the customer’s application.
  2. All Mallory alarms are, at a minimum, function tested 100% during production, and a final audit is performed. Mallory SC/SBM/SNP/LSC/VSB/MSR/MSO series of alarms are audited 100% at final test by checking that sound level, frequency, and current are within specification limits from 2 to 4 different voltage levels. 

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