IBM 3112, Service Manual

Page: 37 / 184

bh1s.bk : bh1sdiag.doc 21 Thu Apr 20 12:42:16 1995
Diagnostic Information
21
engine board, the fuser, and the fuser wiper. Next, measure the voltage
to the fuser lamp during a POR; it should be line voltage until the 922
Error is displayed, if it does not, replace the LVPS, the fuser, and the
fuser wiper.
If the voltage to the fuser lamp is the not the same as the line voltage,
replace the LVPS.
If the lamp, fuser power cable, thermal fuse, thermistor and lamp volt-
age are OK, check J4-16 to see if the engine board is sending the cor-
rect signal to the TRIAC. At POR this signal should go to +5VDC and
then immediately drop to 0VDC until the fuser is warm; if it does not,
replace the engine board. If the signal is OK, replace the LVPS.
Fuser: 923 or 924 Error
Check the connection and continuity of the cable from the fuser exit
sensor board to engine board J8. Check the thermistor condition and
connection.
Check the thermistor resistance at engine board J8-3 to J8-4. It should
be from 100K Ohms to 260K Ohms when cold; it may be as low as 2.3K
Ohms when hot but increase quickly as the fuser cools.
Honeycomb
(Areas of the page are covered by faint 6 mm circles.)
This print defect is usually caused by the print cartridge. If it is not the
problem, verify that the tab on the transfer roll housing is touching the
contact on the HVPS; the transfer roll housing should have continuity to
ground. Make sure the HVPS ground lead to the side frame is in place
and making good contact.
Horizontal Void or Streak
This is usually due to the cartridge not being installed correctly. Check
the printhead area for obstructions, and check the mechanical workings
of the print cartridge and printhead shutter. If nothing is found
see
“Blank Page” on page 16 and follow those instructions.