6-10 Maintenance 8525B/8528 Technical Service Manual
Issue 6 Publication No: 15-02036
6.3 Dismantling and Re-assembly
6.3.1 General
It may be necessary to remove printed circuit boards from the transceiver in
order to carry out certain repairs. The paragraphs which follow give
instructions for the removal and re-installation of boards. While carrying out
these the following general points should be observed:
• Screwdriver—Screws with Pozidrive heads are used in almost all
locations. Ensure that the appropriate screwdriver of the correct size is
used.
• Connectors—The ribbon cable header and multiway connectors used in
some locations can be incorrectly mated with their corresponding
connectors. Care must therefore be taken when re-installing to ensure
that these connectors are correctly mated.
6.3.2 Top and Bottom Covers
To gain access to the boards, the top or bottom cover must be removed from
the transceiver. To remove either cover, the two screws (one on each side)
must be removed and the rear edge of the cover lifted and drawn back so
that the front edge is released from the panel surround.
When re-installing the cover, it should first be placed on the transceiver with
its front edge resting on the two spring clips of the panel surround. The front
edge must then be pressed firmly down while it is slid forward under the
panel surround. When the cover is correctly positioned the rear edge can be
pressed down so that the retaining screws can be re-inserted and tightened.
6.3.3 Circuit Board Removal
Printed circuit boards connected directly to the Motherboard are easily
removed. After disconnecting any flexible leads connected to the board, its
retaining screws can be removed and the multiway sockets on the board can
be withdrawn from the corresponding pins of the Motherboard. This should
be done by progressively raising each socket a small amount so that the
board rises evenly. The procedure is reversed to re-install the boards.
Note: When removing the Audio and IF 1650kHz PCB, the heat sink
secured to the side of the cabinet should be released before the
screws retaining the board. On re-installation it should be secured
last.
To remove the boards mounted behind the front panel, the flexible leads
should be disconnected and the two countersunk screws released from each
side so that the panel can be withdrawn from the cabinet. The two boards
can then be released and separated.
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