Chapter Three – Troubleshooting Guides
45
3.7 SIDERAIL LOCKOUT CONTROLS TROUBLESHOOTING GUIDE
NOTE
Before replacing any circuit boards, ensure applicable cables and connections are intact (visually and me-
chanically). To check for +5 VDC at various points called out in the troubleshooting, use digital ground as
a reference point (negative side of C18 on CPU litter board). When measuring 110 VAC at any point, use
only the neutral (white) side of the power line as a reference point. DO NOT use digital ground as a reference
point when measuring 110 VAC.
PROBLEM/SYMPTOM SOLUTION(S)
Siderail lockout controls will not activate/deactivate
(head, knee and up/down motion lock).
A. Check for +5 VDC at connector P1, pin 6 of the
foot board keyboard (p/n 3000–500–943) (see
page 202 for board location). If voltage is present,
use a voltmeter and verify following switches are
O.K. – SW3 Head Lockout, SW4 Knee Lockout,
SW5 Up/Down Lockout. If switches are not O.K.
and/or LED’s 3–5 are not illuminating when acti-
vated, replace keyboard.
B. Check footboard IFC p/n 3000–500–955 for +5
VDC at connector P2, pin 6. (Pin 7 may be used
for digital ground ref.). If voltage is not present,
check fuse F1. If fuse is O.K. and the problem still
exists, check for 110 VAC at connector P1, pin 18.
If 110 VAC is present, replace litter CPU board. If
110 VAC is not present, check power junction
board (p/n 3000–300–961) at connector P1, pin 1
for 110 VAC (see page 199 for board location). If
voltage is not present, check fuse F1. Replace
fuse, if necessary. If fuse is O.K. and 110 VAC at
connector P1 is not present, check connector J1,
pin 2 for 110 VAC input from power cord. If 110
VAC is present at connector J1 but not at connec-
tor P1, replace power junction board.
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