MBF COMPANY CONFIDENTIAL FIELD INFORMATION BULLETIN

SERVICE GROUP(S): LARGE                MFG: IBM

 NACS  TYPE(S): 0248                   MFG. MODEL(S): 4248

CATEGORY: PRINTER                      DESC: BELT PRINTER

                   *** TABLE OF CONTENTS AS OF 12/20/90 ***
FIB 00001.General Information...............................(Text Inco09/15/87
FIB 00002.MCH CHK 0313................................................11/05/87
FIB 00003.4248.GETS CARRIAGE CHECKS W/REF CODES 8305,8307 AND 8209 ...11/05/87


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                              *** MCH CHK 0313 ***

SYMPTOM/TEXT: MCH CHK 0313 CALLS OUT A3T2 OR MICROCODE AS MOST PROBABLE CAUSE.
RAN 6A THRU 92, TEST 6C FAILS WITH REF 6C31; 6C31 CALLS A3K2. SWAP OUT BOTH
CARDS AND MICROCODE, STILL FAILS.

FIX: THE FIX WAS TO REPLACE THE =5 VOLT LOGIC POWER SUPPLY.
ORIGINATOR: RAY MATTHEWS


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FIB 00003                                                             11/05/87

       *** 4248 GETS CARRIAGE CHECKS W/REF CODES 8305,8307 AND 8209  ***

SYMPTOM/TEXT: CUSTOMER REPORTS CARRIAGE CHECKS. DIAGNOSTIC ROUTINES 82 AND 83   
FAIL WITH REF CODES 8209, 8307 AND 8309.
REPLACED CARRIAGE DRIVE BELT AND MACHINE WOULD RUN TEST FOR A SHORT PERIOD OF   
TIME THEN FAIL WITH THE SAME INDICATIONS AGAIN. THE SAME RESULTS WERE RECEIVED  
AFTER REPLACING BOTH CARRIAGE DRIVE MOTORS,CARRIAGE DRIVE BOARD AND CARRIAGE    
PREDRIVE.BOARDS. ALL VOLTAGES WERE CHECKED ON LOGIC GATE WITH NO DISCREPANCIES  
NOTED. REPLACED TRACTOR DRIVE SHAFT AND BELTS. NO CHANGES WERE NOTED. CARRIAGE  
MOTOR TACH PULSES LOOKED GOOD ON SCOPE.
WHILE.RUNNING THE CARRIAGE, A SLIGHT FLICKER IN THE OPERATOR MESSAGE DISPLAY    
WAS OBSERVED.

PROBLEM ISOLATION AIDS: WHILE CARRIAGE IS MOVING SCOPE TB3 PIN 5 (REF 15-230 OF
 POWER SECTION ). OBSERVED HALF WAVE RECTIFICATION  OF THE +5VDC OUTPUT AT THIS
 POINT. THIS NET IS ONLY USED AT THE OPERATOR PANEL AND THE CARRIAGE DRIVER BOX/
PREDRIVE BOARD. THE VOLTAGE WOULD ALSO DROP BELOW 3.8 VDC DURING CARRIAGE
MOVEMENT.

FIX: REPLACE +5VDC LOGIC SUPPLY. RUN ALL DIAGNOSTICS TO VERIFY CORRECT OPERATION

ORIGINATOR: RAY MATTHEWS  LOGON: 13FPS4


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