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SMC sierra monitor corporation Sentry Instruction Manual - Version 6
SERVICE
Page: 59
Action: check fuse F2 on power supply board. If power
supply jumpers have been cut, cold start requires 110
VAC.
7.2.2.2 POWER SUPPLY ADJUSTMENTS
The +24 volts can be measured at TP1 or TP2 (Test Point 1
or 2) with respect to ground (GT1). Figure 7-3. If there is no
+24 volts and replace fuse F1
The +5 volts can be measured at TP4 If there is no +5 volts
check and replace fuse F3.
The +15 volts can be measured at TP5.
The -12 volts can be measured at TP7
7.2.2.3 LITHIUM BATTERY
The lithium battery which is located on the main control
board, Figure 7-2, looks like a large coin and is mounted in
a round battery holder with a metal retaining clip. Typical
battery voltage should be 3.0 volts and can be measured by
connecting the negative lead of the meter to Ground Test 1
(GT1) on the main control board, and the positive lead to the
shoulder of the battery holder arm. The voltage should be
greater than +2.2 volts or the battery should be replaced. To
remove the battery (use Panasonic BR2325 or equal) use a
nonmetallic probe to carefully lift the metal clip and push the
battery to one side.
It is advisable to increase the tension on both the positive
and negative contacts before installing the new battery. To
do this slide an insulator between the contacts and use a
small screwdriver to lift the lower contact up and push the
upper contact down. Install the new battery with the positive
terminal ("+") facing up. The insulator is important to avoid
shorting the two terminals as this will erase the data
accumulated in RAM.
Battery replacement is necessary when the REPLACE
BATTERY message appears on the lower display during
normal operation. The controller memory of factors,
calibration and history will be retained for a period of several
minutes during battery replacement.
7.2.2.4 EPROM'S
There is one EPROM located on the main control board.
Figure 7-2. The EPROM can be identified by the white label
on the window. The EPROM stores all the software for
Sentry. The EPROM needs replacement when the user
wishes to upgrade to additional options or when a factory
upgrade is issued for the system. The following precautions
must be exercised when replacing the EPROM:
• EPROM’S are sensitive to static discharge and
extreme care must be used in their handling. The
technician should be grounded before picking up
or installing EPROM’S.
• Always remove power to the controller before
removing or installing EPROM’S.
• Before installing check each EPROM for bent
pins.
• Insure that pin orientation is correct, pin 1 toward
center of controller.
• After installation clear RAM using diagnostic
code 0099. (See Section 8.3.5)
• If there is a problem with the EPROM, the display
will read an "E-01" error. This is usually a result
of an improperly installed EPROM.
7.2.2.5 CHANNEL VOLTAGE
There are eight regulated power supplies on the main control
board. The regulators supply power to the module channels.
The voltages which can be measured between the power and
ground connectors of any channel should be between +20.5
and +19.0 volts with no sensor modules connected to any
channel. If the channel voltage is greater than +21 volts that
channel should not be used.
7.2.2.6 ALPHANUMERIC DISPLAY ANGLE
ADJUSTMENT
The alphanumeric display is the lower display on the front
panel. The viewing angle can be altered via the display angle
adjustment potentiometer located on the side of the display
panel. To access the adjustment slide the left panel back and
use a small screwdriver on the only visible potentiometer on
the front panel assembly.
7.2.2.7 RELAY REPLACEMENT
The three socketed DPDT 3 Amp dry contact relays are on
the main control board Figure 7-2. The relay function can be
tested using the TEST ALARMS function of the controller
which causes each relay to throw during the time the
respective display is indicated on the front panel.
It is important that replacement relays be installed in the
same orientation; pin 1 of the relay must line up with pin 1
of the socket.