A B737-300 WITH A CHRONIC #2 GENERATOR DROPPING OFF LINE WAS WORKED BY THE RPTR WITH NO POSITIVE FIX ACCOMPLISHED. LATER FOUND XFER RELAY FAILED.

Narrative

ON JAN/SUN/07; APPROX XA00; AFTER COMPLETING A FAN BLADE SET CHANGE ON AN OTS ACFT; MY LEAD TOLD MR X AND I TO GET A TURNOVER ON ACFT WITH ELECTRICAL PROBS AND TO MOVE IT FROM A TO B. TOLD US THE #2 GENERATOR DROPS OFF LINE AND THAT HE HAD RECONNECTED THE #2 GENERATOR WHICH WAS ON MEL. HE ALSO TOLD US HE DID NOT KNOW THE CAUSE OF THE PROB. MR X TALKED TO MAINT CTL AND DISCOVERED THAT THIS ACFT HAS BEEN HAVING ELECTRICAL PROBS ON ORIGINATING FLTS FOR AWHILE AND THAT TECHNICIAN FOREMEN HAVE BEEN WORKING ON IT. AT APPROX XB00 MR X AND I WENT TO A AND CLOSED #2 ENG COWLS AND BOTH E&E DOORS TO MOVE ACFT. WE PUSHED BACK FROM A AND STARTED BOTH ENGS WITH A NORMAL START; AND PUT BOTH ENG GENERATORS ON LINE. ON TAXI #2 GENERATOR DROPPED OFF LINE. AT THAT TIME WE XFERRED PWR TO APU AND BACK FOR TROUBLESHOOTING; #2 GENERATOR DID NOT COME BACK ON LINE. WE ALSO TRIED RESETTING THRUST REVERSER #2 AND THRUST REVERSER #3 CIRCUIT BREAKERS FOR TROUBLESHOOTING FROM PREVIOUS PROBS. WE ARRIVED AT B AND PARKED THE ACFT AND SHUT DOWN ENG. WE PULLED UP SOME WIRING DIAGRAMS AND A LITTLE MORE TROUBLESHOOTING; BUT OUR SHIFT WAS OVER AT XC00; SO DID A WRITTEN TURNOVER ABOUT #2 GENERATOR DROPPING OFF LINE ON TAXI AND THAT APU PWR WOULD PWR BOTH BUSSES; ETC. MR Y; TOLD ME THAT HE DID FIND THE PROB WITH THE #2 GENERATOR. IT WAS THE R4 'ALT' XFER RELAY. I THEN CHANGED THE R4 RELAY AND SIGNED IT OFF WITH AN OPS CHK REQUIRED.