Loma IQ2 Service Manual page 88

Sig gnd (signal ground)
Tx output (Transmitter)
Tx gnd (Transmitter
ground)
RF input (Receiver input)
RF gnd (Receiver ground)
The search headboard can be replaced as follows: A general component layout
diagram is given in
in Figure 7
1. Isolate the AC power to the detector.
2. Remove the end plate as described in
in this Maintenance section.
3. Carefully unsolder and remove all 16 wires connected to the board.
4. Remove the board and the metal plate to which it is fitted by removing the 4 fixing
screws securing the plate to the detector.
5. Remove the board from its metal plate by removing the 4 fixing screws, spacers & nuts.
6. Take the board to a safe location and lay it on some anti-static packaging; refer to it now
as a reference to ensure the replacement board is properly configured.
Configure as follows: Reference
locations.
•
•
•
•
Module 8023
Figure 8 Search Headboard Connection Details
Figure 6
on page 16
.in this section to help locate items referred to below.
on page 17
Figure 6
Carefully unsolder the L1 inductor, which may be either a fixed value
(small tubular) or a variable copper cased type. This MUST be done
to avoid having to completely re-tune the transmitter after a board
change. If it is a copper cased type the adjustable core/slug inside
MIUST NOT be adjusted.
Check the crystal frequency on the new board (even if it has one)
against the crystal on the old board. If necessary, carefully swap the
crystal from the old to the new.
Check the frequency selection link position on the new board (even if
it has one) against the link on the old board. If necessary fit a link into
the same position on the new board.
Check the link position on JP1 on the new board (even if it has one)
against the link on the old board. If necessary fit a link into the same
position on the new board.
Green
Red (twisted)
Blue (twisted)
Red (screened)
Blue (screened)
and a diagram of the board fixing is given
"End Plate Removal & Refitting"
in this section for component
on page 16
Maintenance
earlier
on page 15
6-18