What was found
PHX - AIR TURN BACK - FLT 0542 - CREW REPORTED THAT DURING CLIMBING OUT AT 7000 FT, FLIGHT ATTENDANTS REPORTED A BURNING ELECTRICAL SMELL THROUGHOUT CABIN. CREW ACCOMPLISHED ODOR REMOVAL CHECKLIST AND RETURNED TO PHX, LANDING WITHOUT FURTHER EVENT. MAINTENANCE DETERMINED THAT THE POTABLE WATER AIR COMPRESSOR WAS THE CAUSE OF ODOR. REMOVED AND REPLACED THE POTABLE WATER AIR COMPRESSOR IAW BOEING 757-200 MM 38-15-01-F. OPERATIONAL CHECKS WERE GOOD. VENDOR CONFIRMED FAILURE. FAILED PRE-TEST, THERMAL PROTECTOR INOP AND SHROUD DAMAGED. THE UNIT WAS REPAIRED AND TESTED IAW CMM 38-15-11 REV.10