GE DigitalFlo XGM868i, Service Manual

Page: 36 / 80

Chapter 4. Parts Replacement
28 DigitalFlow™ XGM868i Service Manual
4.5 Replacing the User Program
The Model XGM868i’s User Program is stored on an erasable programmable read only memory (EPROM) chip. The
EPROM, which is designated as component
U6
, is mounted in a socket on the front of the main circuit board. EPROM
replacement may be required to replace a defective chip or to upgrade to a newer software version.
To replace the User Program, refer to Figure 7 on page 34 and complete the following steps:
1. Complete the steps in Removing the Circuit Board Assembly on page 24.
2. Place the circuit board assembly on a flat surface with the terminal board facing upward. See Illustration 7 in
Figure 7 on page 34, and remove the
three PCB mounting screws (with flat washers and lock washers) indicated.
This will also remove the green grounding jumper .
3. Locate and unscrew a fourth smaller bracket screw close to J2 on the terminal board, capturing the lock washer, flat
washer and bracket nut on the back side. Then, carefully pull the
terminal board away from the main board/power
supply board assembly and option board.
4. Remove the two screws, flat washers, lock washers and heat sink in the corners of the power supply board (see
Illustration 8 in Figure 7 on page 34).
Note:
A XGM868i with a DC power supply will include two more mounting screws, but no heat sink.
5. Carefully pull up the power supply board and heat sink assembly, then slide it out.
The U6 EPROM is located along the upper edge of the main board, on the side that was facing the power supply board
(see Illustration 8 in Figure 7 on page 34). It is the only socketed chip on this board and it has a white identification
label.
6. Using a chip puller, remove the EPROM from its socket. If a chip puller is unavailable, a straightened paper clip
may be used in the notches at the upper right and lower left corners of the socket. Gently pry the EPROM up, a
little at a time, at each notch until it comes free.
CAUTION! The EPROM is easily damaged by static electricity. Before handling the new chip, touch a
grounded metal object to discharge any built-up static electricity and avoid touching the leads
on the side of the chip.
7. Make sure that the beveled corner on the new EPROM is aligned with the beveled corner of the socket and place
the EPROM into the socket.
8. By applying equal pressure on all four corners, gently press the EPROM into the socket until it is fully seated. Do
not strike the EPROM or apply excessive force during this procedure.
Complete the User Program replacement by proceeding to Assembling the Circuit Board Assembly on page 30.