T-SM47j P45/54
T20-a
OPERATION TABLE
6.6.13.4 Replace the new height potentiometer loom and
reconnect it to the four actuator PCA. Re-fasten the cable
to the table base and replace the covers. The height
potentiometer must now be calibrated, check Appendix 2
and proceed as detailed in the ‘Application software
manual’.
6.6.14 Traverse motor loom and microswitches
The traverse motor loom and microswitches are within the
crossbeam, see Fig. 6.7. (Note that all T20-a tables have
the later switch arrangement). Change the traverse motor
loom and microswitches as follows:
i Place table into the ‘Service position’ as detailed in
section 1.9 (noting safety warnings in section 4.0)
and then remove the bottom crossbeam cover (item
17 of Fig. 6.7).
ii Loosen the four set screws in the two traverse limit
switch cams and slide out the traverse limit switch
pins (take care not to lose the springs or headed
bushes noting orientation). Disconnect the loom from
the three actuator PCA.
iii Remove the M4 screws securing the two traverse
limit switch brackets, slide them down and away from
the cross beam and release the microswitches.
iv Fasten the new traverse motor loom microswitches
onto the traverse limit switch brackets and
reassemble by reversing the above, ensure the limit
switch pins are fully inserted into the cams and are
aligned without any torsional spring. Check the
microswitches change state when the traverse limit
switch pins are pressed and that all pins move freely.
v Check the new loom has been routed correctly and
connected onto the three actuator PCA.
Reassemble the table and carry out a full table
function test.
6.6.15 Connector block assemblies and looms
The connector block assemblies (top, item 5 of Fig. 6.7
and bottom, item 14 of Fig. 6.3) enable the trunk sections
to be removed without disconnecting any looms or wiring.
Each part of the connector block assembly has a loom
attached. These items are replaced as follows:
i To replace the top connector block and loom (which
connects to the three actuator PCA) proceed as
follows:
a) Gain access to inside the crossbeam by
removing the head and leg section and then the
trunk sections as detailed in section 6.2.5 for
bellows replacement noting the warning at the
beginning of section 6.2.5.
b) Remove the cross beam top cover (item 10 of
Fig. 6.7) to gain access to the top connector
block and loom. Remove the ring crimp terminals
of the loom where they connect to the connector
block noting connection annotation (R O Y B)
for reconnection.
c) If replacing the loom disconnect it from the three
actuator PCA and connect the new loom back as
found. If replacing the top connector block release
the two M6 screws to remove it, replace the new
block and remake the ring crimp connections.
ii To replace the lower connector block and loom
(which connects to the four actuator PCA) proceed
as follows:
a) Remove the trunk sections from the table as
detailed in section 6.2.5 for bellows replacement
noting the warning at the beginning of section
6.2.5, but note that only the metal top of column
covers (items 12, 13 and 14 of Fig. 6.1) need to
be removed, the bellows can remain attached.
b) Remove the top of column cover (item 11 of
Fig. 6.1).
c) Remove the ring crimp terminals of the loom
where they connect to the connector block noting
connection annotation (R O Y B) for reconnection.
d) If replacing the loom disconnect it from the four
actuator PCA and connect the new loom back
as found. If replacing the lower connector block
release the two M8 screws to remove it, replace
the new block and remake the ring crimp
connections.
iii Reassemble the table and carry out a full table
function test.
6.6.16 Switch and accessory panel looms
To replace either of these looms proceed as follows:
i Release the top of the bellows as detailed in 6.2.3.5.
ii Remove the connections from the PCA and then
from inside the bellows release the retaining screws
to remove the switch or accessory panel loom.
iii Replace the required loom, reassemble the table
and carry out a full table function test.
6.6.17 Column energy chain and loom
To replace a column energy chain and loom (item 10 of
Fig. 6.8) proceed as follows:
i Gain access to the lower column by lifting the
telescopic covers as detailed in section 6.2.3.2 then
remove the base covers as detailed in section 6.2.2.
ii Remove the two remaining connections coming from
the bottom of the column energy chain loom where
they join the mains panel and the power supply
assembly. (Note that the other two connections to
the infrared PCAs were removed when taking off
the covers).
iii Remove the single connection coming from the top
of the loom where it joins the four actuator PCA.
Remove all other cable ties and loom restraints.
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