SMA Y HAD LTSS FROM SMT X. NMAC. SYS ERROR.

Narrative

I HAD SMT X AT 70 ON V510 SEBOUND AND WAS CLBING SMA Y NW ON V510 TO 80. SMA Y WAS CLBING SLOW AND WAS JUST REACHING 50 WHEN I TURNED HIM 15 DEG OFF THE AIRWAY; 'VECTOR FOR CLB; OPPOSITE DIRECTION TFC; 12 O'CLOCK AND 10 MI.' SMA Y ACKNOWLEDGED AND READ BACK THE HDG OF 280 DEG. I THOUGHT ABOUT STOPPING SMA Y'S CLB AT 60 BUT DUE TO THE CONVENTION WE WERE HAVING TROUBLE COORD WITH CHICAGO CENTER SO I WANTED HIM LEVEL AT 80 BEFORE MAKING MY HDOF. I HAD SENT 2 70'S TO S RADAR ALREADY AND WAS ABOUT TO SEND 2 MORE (ALL XING) SO STARTED TO COORD A PLAN OF ACTION WITH THE S CTLR AS HE ALREADY HAD 4 XING 70'S AND WAS ABOUT TO GET 2 MORE. WHEN I NOTICED THE SITUATION; SMA Y WAS LEAVING 60 AND WAS 5 MI AWAY. HE WAS ALSO ON THE CENTERLINE OF THE AIRWAY. AS I WAS ABOUT TO ISSUE EVASIVE TURNS TO BOTH ACFT; A THIRD ACFT CAME ON THE AIR WITH A PIREP. (AFTER LISTENING TO THE TAPE; THE PIREP TOOK APPROX 18 SECS). BY THE TIME THE PIREP WAS FINISHED; THE SMA Y WAS THROUGH 64 AND WAS AT 3 OR LESS AND 12 O'CLOCK. I IMMEDIATELY ISSUED EVASIVE TURNS TO BOTH ACFT. TARGETS MERGED AND I NEVER SAW THE ALT READOUT. BY THIS TIME I HAD TOLD MY SUPVR (AT THE DATA POS) I HAVE AN ERROR; AND HE ADVISED I HAD 500 FT AT THE TIME THEY MERGED. AFTER THEY PASSED; I PUT THEM BOTH BACK ON COURSE. SMA Y ADVISED IT WAS A 'NEAR MISS'. CONTRIBUTING FACTORS: EXPERIENCE TOLD ME TO LEVEL SMA Y AT 60 BUT LANDLINE SITUATION MADE ME CHANGE. IF S SIDE RADAR WOULD HAVE NEEDED HELP; HE WOULD HAVE ASKED; OR NOT TAKEN MY HDOFS; YET I LET MY ATTN BE DIVERTED TO HIS AIRSPACE. THE PIREP GOT IN THE WAY. I FEEL IF A PLT IS GOING TO MAKE A LONG XMISSION; HE SHOULD FIRST ASK IF THE CTLR IS READY.