Sentry Sample II Low Pressure Installation, Operation & Maintenance Manual page 31

Controller
Fuses
Potential Fire Hazard – Replace fuses only with the same fuse type and ratings .
The two circuit boards in the Sample Sentry II contain fuses to protect personnel, wiring
and the electronics from excessive current draw. Each fuse requires a different trip rating.
Individual fuse ratings can be found in the Spare Parts List included in this manual.
The power supply uses a 4 A fast acting fuse rated for 250 V.
Replacement fuses for the power supply and circuit boards are available from Sentry. Refer
to the "Spare Parts List" on page 37 of this manual for further information. Refer to the
disassembly procedure for instructions on replacing user replaceable parts such as fuses.
Disassembly
Electrical Shock Hazard – Disconnect all power, including voltages connected to relays, before
servicing or replacing fuses .
Use the following steps to replace any user serviceable parts:
1. Remove the front cover of the enclosure by removing the four corner screws.
Disconnect the keypad extension cable from the CPU board.
2. Disconnect the interface cable and power supply cable from the CPU board. Remove
the CPU board by removing the four mounting screws.
3. Disconnect the power supply cables from the power supply. Remove the power supply
by removing the four mounting screws.
4. Replace desired part, such as fuse, circuit board or cable assembly.
5. Replace the power supply. Secure the board in place using the four mounting screws
removed in step 3. Replace the power supply cables.
6. Replace the CPU board. Secure the board in place using the four screws removed in
step 2. Replace the interface cable and power supply cable.
 NOTE
When the CPU board is replaced, the default valve needs to be configured . Use the following
procedure to select the PRV valve type .
1 . Connect power to the Sample Sentry II .
2 . While the Sample Sentry II boots, hold down the and MENU buttons at the same time to
bypass the startup sequence and enter the main menu .
3 . Enter password (101) . Holding the menu key while pressing the up and down arrows to adjust
value by 100 .
Sentry Sample Sentry II 31