GE DigitalFlow DF968, Service Manual

Page: 47 / 78

March 2008
4-4 Parts Replacement
Removing the Printed
Circuit Board (cont.)
If the printed circuit board is being replaced, proceed to the section on
Installing the Printed Circuit Board (page 4-7) now. Otherwise, refer
to the appropriate section for instructions on Installing an Option
Card (page 4-5), Replacing the EPROM (below) , or Replacing the
LCD Display (page 4-6).
Replacing the EPROM
The Model DF868’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 4-2 on page 4-11
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.
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.
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.
Complete the EPROM replacement by proceeding to the Installing
the Printed Circuit Board (page 4-7) section of this chapter.
Note:
If you have installed a new EPROM, upon reinitialization the
DF868 displays a message “Slot x Params, appended.” This
message directs users to check the slot error handling on the
option cards, and appears on power up until you review the
parameters in the I/O submenu (OPTN option).