IBM 3112, Service Manual

Page: 44 / 184

bh1s.bk : bh1sdiag.doc 28 Thu Apr 20 12:42:16 1995
28
Service Manual
•
The D-roll will not move at all. Check the paper feed magnet
adjustment. If the adjustment is correct, either the paper feed
magnet is defective or the engine board signal is incorrect.
Check the resistance of the paper feed magnet J14-1 to J14-2
for 100-250 ohms. If the resistance is correct, replace the engine
board.
•
The D-roll will move slightly but will not complete an entire
revolution. This indicates a bind or defect in the gear train.
If paper is jamming, clean the paper path of obstructions or repair any
damaged parts. Very thin or thick paper, labels, transparencies, or card
stock will have a higher jam rate than regular xerographic paper. Check
the condition of the paper in the tray and verify that the tray is installed
correctly. If the paper feeds but stops undamaged in the paper path run
the input and exit sensor test. Check for +5VDC at the input sensor
(engine board J9-6) and exit sensor (engine board J8-6) with paper
present. Check continuity on the cable before replacing a sensor.
If paper is curling badly enough to cause a problem feeding or stacking,
see “Fuser Temperature And Warm-Up Time” on page 43.
Paper Feed, Duplex Unit
Check that all gears and belts are working correctly both in the duplex
unit and on the tray top cover, and that the gear on the tray top cover
correctly engages the gear on the duplexer.
If paper is jamming in the table cover area, make sure the table cover is
properly installed. Run diagnostics Duplex Test 1 to make sure the
paper is feeding far enough into the duplex unit before reversing. Exam-
ine the condition of all rollers.
If paper is stopping or jamming as it is fed back across the top of the
paper tray, run diagnostics Duplex Test 2 to make sure there is no slip-
page in the paper path. Make sure the paper tray top cover is not dam-
aged. Cold paper curl can also cause jams here;
see
“Fuser
Temperature And Warm-Up Time” on page 43.
If paper is jamming at the front exit of the printer, inspect the duplex exit
selector switch and the linkage to the printer exit deflector. Check the
switch by removing the duplex top cover and table cover and reinstall-
ing the duplexer in the printer. Check for +5VDC at duplex system