GE DigitalFlow DF868, Руководство по обслуживанию

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Chapter 4. Parts Replacement
30 DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Service Manual
4.4 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 9 on page 36 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 32) 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).
4.5 Installing an Option Card
The Model DF868 flowmeter can accommodate up to six option cards. The option cards are installed into sockets on
the rear of the printed circuit board, and they are held in place with a metal bracket. A single metal bracket is used to
secure all the installed option cards.
Note:
If the Model DF868 presently has no option cards installed, be sure to purchase the metal mounting bracket
along with the first option card.
To install an option card, refer to Figure 9 on page 36 and complete the following steps:
1. Remove the printed circuit board, as described on page 29.
2. If one or more option cards are already installed, remove the four fasteners that secure the metal bracket to the
printed circuit board. Lift the metal bracket straight up and away from the printed circuit board.
Note:
The fasteners may be either plastic snap rivets or metal hardware (in some older meters). In either case, they
may be discarded, as new plastic snap rivets are provided.