IBM 6400 Maintenance Information Manual page 119

Symptom
Stacker limit switch
check
Table 5. General Symptom List
NOTE: This procedure tests the motion limit switches at the top and
bottom of the vertical rails. You will usually be referred to
this procedure from other troubleshooting procedures.
When you have completed this procedure, return to the
procedure that sent you here.
1. Power off the printer. Open the rear cabinet door. Unload the
power stacker. Move the elevator up and down by hand,
checking that it moves smoothly and without chattering or
shuddering. Eliminate causes of chattering or shuddering. (E.g.,
loose, damaged, or broken constant force springs, bent or
misaligned rails, obstructions, etc.)
NOTE: If the elevator assembly or the rails are bent or damaged,
you must replace the entire power stacker assembly.
2. Move the elevator up and down by hand. Check that the limit
switches are physically tripped when elevator reaches top and
bottom of travel. If necessary, gently bend the contact arms to
adjust limit switches. If you cannot adjust a switch that requires
adjustment, replace it.
3. a) Unfasten the cable clamp holding the stacker control panel
cables.
b) Disconnect stacker rail cable connector P107 from connector
J3 on the back of the stacker control panel. (See Figure 68,
page 376.)
c) Locate pin 1 of connector P107. (See the cable assembly
drawing in Appendix A, page 321.)
d) Check the stacker rail cable and limit switches for continuity
and shorts. Check continuity of the switch when open and
closed. (See the power stacker control panel PCBA pinout
drawing on page 298. STK FULL is the upper limit switch, STK
LIMIT is the bottom switch.)
Replace the stacker rail cable if it is damaged or fails continuity
test. Replace any switch that fails continuity test.
General Symptom List
Corrective Action
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