OMNI

Additional Manufacturer Narrative

THIS EVENT OCCURRED IN (B)(6).

Description of Event or Problem

THE CUSTOMER REPORTED THAT THEY PERCEIVED A CHARRED SMELL OF THE DEVICE. THE CUSTOMER SWITCHED OFF THE SYSTEM. NO ADVERSE EVENTS OCCURRED FOR THIS EVENT. THE FIELD SERVICE ENGINEER CHANGED THE POWER SUPPLY OF THE DEVICE. WITH THE NEW POWER SUPPLY, THE DEVICE WAS SAID TO BE WORKING FINE. THE AFFECTED POWER SUPPLY WAS INVESTIGATED. THE FIRST VISUAL INSPECTION SHOWED NO SIGN OF BURNING ON THE ELECTRONIC COMPONENTS. A FAINT SMELL OF BURNED COMPONENTS COULD BE DETECTED NEAR THE POWER SUPPLIER BOX. THE OPENED POWER SUPPLY SHOWED A LOT OF DUST INSIDE. UPON FURTHER INVESTIGATION OF THE POWER SUPPLY UNIT, A DEFECTIVE BLOWN VARISTOR WAS FOUND WITHIN THE POWER SUPPLY. THERE WAS VISUAL EVIDENCE THAT THE PART HAD BURNED OR MELTED. THE INPUT FUSE ON THE AC/DC MODULE WAS ALSO BLOWN. THE VARISTOR IS RESPONSIBLE FOR LIMITING OVERVOLTAGE. IF THE ENERGY IS TOO HIGH, THE VARISTOR WILL BE DESTROYED AND OFTEN CAUSE A SHORT CIRCUIT. THE SHORT CIRCUIT CAUSES THE INPUT FUSE OF THE AC/DC MODULE TO BLOW AND CAUSED THE BURNING SMELL. NO SPECIFIC CAUSE OF THE VARISTOR FAILURE COULD BE DETECTED. IT IS ASSUMED THAT THE FAILURE WAS DUE TO AGING OF THE VARISTOR. THE RISK OF FIRE IS HIGHLY UNLIKELY AS THE SURROUNDING MATERIAL OF THE DEFECTIVE VARISTOR IS FIRE RETARDANT MATERIAL.