IM 01C25B01-01E
8-4
8. MAINTENANCE
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 connec-
tor 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 connec-
tor 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 assem-
bly. 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 subsec-
tion 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 re-
placed.
• 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.
