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PFP7/REV C/01-08
9.1.3
Thermocouple removal
1. Ensure that power is disconnected from the instrument. If the flame has been alight
allow 30 minutes for the burner and chimney to cool down.
2. When cool, unscrew the cap that holds the thermocouple in place, taking care not to
loosen the housing retaining nut. Remove the thermocouple complete with the
compression fixing.
3. Unscrew the thermocouple wires from the terminal block on the power supply PCB. Pull
the wires through the grommet in the side panel. If re-fitting a replacement
thermocouple ensure it is pushed through the housing as far as it will go before
clamping the compression fitting. Ensure correct polarity is observed when fitting into
the terminal block.
9.1.4
Filter wheel and filters
Refer to
Figure
9.1.3
.
1. Ensure that power is disconnected from the instrument. Remove the four socket head
screws from the right hand side panel. Remove both left and right hand side panels and
place carefully to one side.
2. Remove the filter select knob. Unscrew the four screws on the bottom of the unit that
hold the chimney assembly in place. Carefully remove the chimney assembly from the
unit. Remove the four screws on the cover plate to release the filter wheel assembly
from the chimney assembly. Remove the two grub screws from the filter wheel to gain
access to the filters.
3. To fit additional filters: push out the round plastic blanking piece; fit the new filter into
the vacant position with the mirrored side towards the flame. Replace the circlip to
retain the new filter and replace the filter wheel.
4. Ensure that the PIN diode housing is in alignment with the filter recess. This can be
achieved by loosening the filter wheel via the two retaining grub screws and pushing the
PIN diode housing into the filter recess. Tighten the filter wheel in this position and slide
the PIN housing back to just clear the filter wheel in all positions.
9.1.5
PIN diode PCB removal
Refer to
Figure
9.1.3
.
1. Ensure that power is disconnected from the instrument. Remove the right hand side
panel as detailed in the previous sub-section.
2. Unplug the 3 pin connector from the PIN diode mounting PCB (UOD1). The PCB may
be removed complete with half of the mounting bracket by removing the two pozidriv
screws that pass through the adjusting slots into the captive nuts on the other half of the
bracket.
3. Replacement is the reverse of removal. Check that the diode is aligned with the optical
path on re-assembly as described in section 9.1.4