GE DigitalFlo XGM868i, Service Manual

Page: 38 / 80

Chapter 4. Parts Replacement
30 DigitalFlow™ XGM868i Service Manual
4.6.1 Attaching an Optional Heat Sink to an I/O Option Card
If you need to attach an optional heat sink to an I/O option card (the TI, TR, FI or FR options in Appendix B of the
Startup Guide) , refer to Illustration 9 in Figure 8 on page 35 and complete the following steps:
1. Orient the thermal heat pad(s) to the heat sink as shown in Figure 8 on page 35 and apply it to the heat sink.
2. Loosely attach the aluminum backplate to the I/O heat sink with three screws, lock washers and flat washers.
Note: The following step applies only to the TR and FR option cards. Otherwise, proceed to step 4.
3. If you have an optional heat sink bridge, attach it to the I/O heat sink with two screws, lock washers, flat washers
and nuts.
4. Attach the assembled heat sink by straddling the power supply components on the option card with the aluminum
plate to the left (inside) and the heat sink to the right (outside).
5. Tighten the three screws (step 2) to secure the aluminum backplate to the heat sink.
Complete the option card installation by proceeding to Assembling the Circuit Board Assembly below.
4.7 Assembling/Installing the Circuit Board Assembly
Most of the parts replacement procedures described in this chapter require removal of the circuit board assembly from
the electronics enclosure. Furthermore, most of the procedures require varying degrees of disassembly of the circuit
board assembly. See Figure 8 on page 35 and follow the instructions in this section to assemble the circuit board
assembly and/or to install it in the electronics enclosure.
4.7.1 Assembling the Circuit Board Assembly
If the circuit board assembly has been disassembled to any degree, complete the steps below. Otherwise proceed
directly to
Installing the Circuit Board Assembly on page 32. See Figure 8 on page 35 and complete the following
steps:
1. If necessary, replace the angle bracket on the main board, insert the screw (with flat washer and lock washer), and
screw it into the standoff on the main board. See Illustration 11 in Figure 8 on page 35.
IMPORTANT:
The small angle bracket on the terminal board must be positioned on the outside of the main board with
the previously removed nylon washer between them.
2. Face the User Program side of the main board toward the rear of the power supply board. Orient the boards so that
the pins along the bottom of the main board align with connectors J2 and J6 on the power supply board, and push
the two boards firmly together.