Yokogawa EJA310E - Manual (Page 43)

<8. Maintenance>
8-4
IM 01C25B01-01E
8.4.2 Replacing the CPU Board Assembly
This subsection describes the procedure for
replacing the CPU assembly. (See figure 8.3)
■ Removing the CPU Assembly
1) Remove the cover. If an integral indicator is
mounted, refer to subsection 8.4.1 and remove
the indicator.
2) Turn the zero-adjustment screw to the position
(where the screw head slot is horizontal) as
shown in figure 8.3.
3) Disconnect the output terminal cable (cable
with brown connector at the end). When doing
this, lightly press the side of the CPU assembly
connector and pull the cable connector to
disengage.
4) Use a socket driver (width across flats, 5.5mm)
to loosen the two bosses.
5) Carefully pull the CPU assembly straight
forward to remove it.
6) Disconnect the flat cable (cable with white
connector at the end) that connects the CPU
assembly and the capsule.
NOTE
Be careful not to apply excessive force to the
CPU assembly when removing it.
■ Mounting the CPU Assembly
1) Connect the flat cable (with white connector)
between the CPU assembly and the capsule.
2) Connect the output terminal cable (with brown
connector).
NOTE
Make certain that the cables do not get pinched
between the case and the edge of the CPU
assembly.
3) Align and engage the zero-adjustment screw
pin with the groove on the bracket on the CPU
assembly. Then insert the CPU board assembly
straight onto the post in the amplifier case.
4) Tighten the two bosses. If the transmitter is
equipped with an integral indicator, refer to
subsection 8.4.1 to mount the indicator.
NOTE
Confirm that the zero-adjustment screw pin is
placed properly in the groove on the bracket prior
to tightening the two bosses. If it is not, the zero-
adjustment mechanism will be damaged.
5) Replace the cover.
8.4.3 Cleaning and Replacing the Capsule
Assembly
This subsection describes the procedures for
cleaning and replacing the capsule assembly. (See
figure 8.4.)
CAUTION
Cautions for Flameproof Type Transmitters
Users are prohibited by law from modifying the
construction of a flameproof type transmitter. If
you wish to replace the capsule assembly with
one of a different measurement range, contact
Yokogawa.
The user is permitted, however, to replace a
capsule assembly with another of the same
measurement range. When doing so, be sure to
observe the following.
• The replacement capsule assembly must
have the same part number as the one being
replaced.
• The section connecting the transmitter and
capsule assembly is a critical element in
preservation of flameproof performance, and
must be checked to verify that it is free of
dents, scratches, and other defects.
• After completing maintenance, be sure to
securely tighten the setscrews that fasten
the transmitter section and pressure-detector
section together.