Panametrics DigitalFlow XMT868i, Руководство по обслуживанию, Страница: 36 / 74

Chapter 4. Parts Replacement
2 DigitalFlow™ XMT868i Service Manual
4.2 Removing the Circuit Board Assembly
All parts replacement procedures for the Model XMT868i require the removal of the circuit board assembly from the
electronics enclosure. Therefore, complete the instructions in this section before attempting any other service tasks.
The Model XMT868i circuit board assembly consists of circular front and rear circuit boards with several rectangular
circuit boards sandwiched between the circular end boards and oriented perpendicular to them. Specifically, some
or all of the following circuit boards may be included in the assembly:
FRONT BOARDS:
•
LCD Display/Interconnect Board Subassembly
REAR BOARD:
•
Terminal Board
MIDDLE BOARDS:
•
Main Board
• Receiver Board
• Power Supply Board
• Slot 1 Input/Output Card (optional)
• Slot 2 Logging or Communication Card (optional)
To disassemble the circuit board assembly, refer to Figure 7 on page 11 and complete the following steps:
1. Disconnect the power to the XMT868i and move the electronics enclosure to a safe area.
Note: If the electronics enclosure cannot be moved to a safe area, be sure the surrounding area is free of ignitable
gases before proceeding to step 2.
WARNING!
The main power to the Model XMT868i must be disconnected before proceeding.
2. Refer to Illustration 1 in Figure 7 on page 11. Loosen the set screw on the rear cover. Place a rod or long screwdriver
across the cover in the slots provided, and rotate the cover counterclockwise until it comes free from the
enclosure.
3. Repeat Step 2 to remove the front cover.From the rear of the enclosure, disconnect the power line leads from
terminal block TB5. Unplug terminal blocks TB1 to TB6 from connectors J1-J4.
4. Refer to Illustration 2 in Figure 7 on page 11, and remove the four terminal board mounting screws and the ground
screw. This will disconnect one end of the green grounding jumper wire and the label plate with the ground
symbol will come loose from beneath it.
IMPORTANT: Each screw will have a flat washer and a lock washer over it. Be careful not to lose these washers.
5. Carefully rotate the circuit board assembly counterclockwise about 20°, until the five bosses in the enclosure are
visible through the slots along the circumference of the terminal board. Then, slowly push the circuit board
assembly through the enclosure and remove it from the front of the enclosure. Refer to Illustration 3 in Figure 7 on
page 11.
Bring the circuit board assembly to a clean, safe work area and proceed to the appropriate section of this chapter to
perform the desired service procedure.