MOUNTING BRACKET
SCREWS (4)
3
OPLS
OPHM
S/N16
- +
measure resistance
between pin 3 of
No
Yes
PIN 1
PIN 2
PIN 3
(Front View)
[7] Using ohmmeter,
[9] Replace
[4] Is
clock chain
cover removed
[8] Is
resistance
between 66 ohms
and 70 ohms
No
terminal of coil
and positive (
+
)
AND
AND
OR1
68
FLATHEAD SCREW (4)
OSC
OS
MSO
(FRONT)
remove power from clock chain
panhead screws holding rear of
network clock chain control
flathead screws and network
clock chain control cover
[3] Depress
ROS/OFF
switch to
[5] At rear of frame, remove six
[6] At front of frame, remove four
[1] See CAUTION 1. Obtain
volt/ohmmeter (KS-14510)
CLEAR R1 OR PLS FAULT — 39B OSCILLATOR
R1
PLS
[2] At appropriate power switch,
PLS
SCREWS (6 PANHEAD)
CONTROL COVER
(REAR)
ensure
ROS/OFF
switch is
OFF NORM
lamps lighted)
rotated to
ROS
(
OS
and
lighted)
(
OFF NORM
and
PWR OFF
lamps
Yes
CAUTION 1
Always remove
NCSU from service
and disable all
oscillators (using
switch) before
working on any
network clock
problem
ENABLE/DISABLE
Figure 1 - Network Clock Control
[Figure 3]
Figure 3 — R1/PLS Circuit Schematic
Figure 2 — PLS Circuit
switch [Figure 2]
cover [Figure 1]
TAP
PAGE 1 of 2
234-151-013
128
Issue 8
DEC 1995
