GE DigitalFlow GF868, Service Manual

Page: 44 / 74

Chapter 4. Parts Replacement
34 DigitalFlow™ GS868 Service Manual
4.3 Replacing the EPROM
The Model GS868’s User Program is stored on an erasable programmable read only memory (EPROM) chip. The
EPROM, which is designated as component
U4
, is located in the top left corner of the rear of the printed circuit board.
See Figure 9 on page 40 for a rear view of the printed circuit board.
EPROM replacement may be required to replace a defective chip or to upgrade to a newer software version. To replace
the EPROM, complete the following steps:
1. Remove the printed circuit board, as described in a previous section of this chapter.
2. Place the printed circuit board face down on a clean, flat surface. Locate the EPROM socket in the top left corner
of the board.
3. 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.
4. 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.
5. 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.
To complete the EPROM replacement, proceed to Installing the Printed Circuit Board on page 37.
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.