What was found
THREE GARMIN AUDIO PANELS GMA 340 HAD TO BE SENT BACK TO GARMIN FOR REPAIRS DUE TO A SHORT CIRCUIT OCCURRING WHEN PLUGGING IN HEADSETS WITH THE MASTER SWITCH ON. FIRST WAS ON JANUARY 17, 2006, LAST TWO OCCURRED ON SAME DAY FEB 2, 2006. OPERATING AIRCRAFT FOR A LITTLE MORE THAN TWO YEARS, SUSPECTED FIRST FAILURE MAY HAVE BEEN AN ISOLATED EVENT DUE TO FACT THAT REPLACEMENT OF UNIT, WITH A LOANER, FROM ATLANTIC AVIONICS, WORKED JUST FINE. DIAMOND ISSUED SB DAC1-23-01 REV 0 TITLED DA20 C1 - GMA 340 ISOLATION DIODES ISSUED 08 DECEMBER 2004. NOT PROVIDED A COPY OF BULLETIN UNTIL AFTER FAILURES.