Manual revision 041
Appendix II: Electronics Disassembly/Reassembly
SBE 37-SM RS-232
73
Appendix II: Electronics
Disassembly/Reassembly
Disassembly
1.
Remove the end cap and battery pack following instructions in
Section 3:
Preparing MicroCAT for Deployment
.
Do not remove the
titanium guard!
2.
The electronics are on a sandwich of three rectangular PCBs. These PCBs
are assembled to a bulkhead that can be seen at the bottom of the battery
compartment. To remove the PCB assembly:
A.
Use a long screwdriver (#1 screwdriver) to remove the Phillips-head
screw at the bottom of the battery compartment. The Phillips-head
screw is a 198 mm (7.8 inch) threaded rod with Phillips-head.
B.
Pull out the PCB assembly using the PVC pylon (post with Molex
connector). The assembly will pull away from the 10-position edge
connector used to connect to the sensors.
Reassembly
1.
Sight down into the MicroCAT housing to find the hole into which the
Phillips-head screw threads. The hole is at the bottom of the housing, next
to the edge connector. The small-diameter brass sleeve between two of the
PCBs guides the screw into the hole. Align this sleeve with the hole.
2.
Guide the PCB assembly into the housing and push the assembly until the
edge connector is fully inserted. A gentle resistance can be felt during the
last 3 mm (
1
/
8
inch) of insertion as the PCB assembly mates to the
edge connector.
3.
Drop the Phillips-head screw into the hole and tighten gently.
4.
If it is difficult to align the cards, obtain a 305mm (12 inch) length of
6-32 threaded rod.
A.
Thread the end of this rod into the hole at the bottom of the housing
(next to the edge connector).
B.
Slide the PCB assembly’s small diameter brass sleeve down the rod.
The rod will help guide the assembly into the proper position.
C.
Push the assembly until the edge connector is fully inserted.
After the PCB assembly has been fully inserted, remove the rod.
D.
Drop the Phillips-head screw into the hole and tighten gently.
5.
Reinstall the battery pack and end cap following instructions in
Section 3:
Preparing MicroCAT for Deployment
.
Note:
Before delivery, a desiccant package is
inserted in the housing and the
electronics chamber is filled with dry
Argon gas. These measures help
prevent condensation. To ensure
proper functioning:
1. Install a new desiccant bag each
time you open the electronics
chamber. If a new bag is not
available, see
Application
Note 71: Desiccant Use and
Regeneration (drying)
.
2. If possible, dry gas backfill each
time you open the housing. If you
cannot, wait at least 24 hours
before redeploying, to allow the
desiccant to remove any moisture
from the housing.
Note that opening the battery
compartment does not affect
desiccation of the electronics.
Note:
If the rod will not tighten, the PCBs
have not fully mated or are mated
in reverse.
CAUTION:
See
Section 5: Routine Maintenance
and Calibration
for handling
instructions for the plastic
ShallowCAT
housing.
