RPTR AT ANC TRACON ALLEGES THAT AIRWAYS FACILITIES TECHNICIAN CAUSED ASR-9 RADAR TO FAIL WHILE HE PERFORMED A MAINT FUNCTION. NO INCIDENTS OCCURRED DURING OUTAGE.

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ANC TRACON RADAR MAINT ADVISED ATC THEY WERE GOING TO PERFORM A MAINT FUNCTION ON THE RADAR. SOON THEREAFTER; THINGS WENT AWRY. ACFT POS WAS INSTANTLY OFF BY 10 MI; HDG OFF BY 30 DEGS. I ASKED IFR ACFT IF HE WAS IN VFR CONDITIONS; TERMINATED RADAR SVC; AND ADVISED PLT OF RADAR FAILURE. I INSTRUCTED PLT TO MAINTAIN VFR AND GAVE POS OF KNOWN TFC; A POTENTIALLY CONFLICTING SBOUND CV58. PLT ADVISED HE HAD FIELD IN SIGHT AND WAS CLRED FOR VISUAL APCH. SHORTLY AFTER; RADAR RETURNED TO NORMAL. NO CONFLICT WAS EVIDENT; MD11 SHIPPED TO TWR. THIS IS THE SECOND SUCH OCCURRENCE IN LESS THAN 2 WKS. SUPPLEMENTAL INFO FROM ACN 348770: RADAR MAINT ADVISED THAT THEY WERE GOING TO PERFORM MAINT ON THE RCAG. SUDDENLY ALL TARGETS WERE OFF BY SEVERAL (10-15) MI. THE MD80 WAS NEARING TERRAIN IN THE CLB. I COULD NO LONGER MONITOR HIS CLB RATE WITH RESPECT TO THE TERRAIN; AND HIGHER MVA HE WAS NEARING. LUCKILY; HE WAS VMC AND ABLE TO PROVIDE HIS OWN TERRAIN SEPARATION. I HAD 2 OTHER ACFT (THE B737 AND A CV58) IN THE AIRSPACE AT THE TIME. I FELT REASONABLY CERTAIN THAT THEY WERE CLR OF TFC AND TERRAIN; SO I TOOK NO IMMEDIATE ACTION. THE RADAR SUBSEQUENTLY CHANGED AZIMUTH BY ABOUT 90 DEGS! THIS SAME THING HAPPENED TO ME ABOUT 2 WKS AGO; ALTHOUGH THIS TIME THE TECHNICIAN GAVE A 'HEADS UP.' BUT; HE SAID HE WAS ONLY GOING TO WORK ON THE RCAG; WHICH SHOULD NOT HAVE AFFECTED ANYTHING. THIS HAS GOT TO STOP BEFORE WE KILL SOMEONE.