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4. CIRCUIT BOARD
ASSEMBLY
The circuit board will be supplied with one side printed with all the component locations - this is the
side the components go. This printing is reproduced as fig 6 I See reverse side of sheet) since some of
the markings will be covered by components All soldering is done on the other side which is coated
with a green solder resist - this keeps the solder away from where it is not needed The exception is
the edge connector area which should be kept free of solder to ensure reliable connection to the RAM
pack or printer if they are used We suggest you assemble the components in the following order,
although it is not compulsory:
(i) Resistors, capacitors and I C sockets - do not plug the LC.s in yet
(M) The diodes and transistors.
(iti) The
large' components: the sockets, keyboard connectors, modulator, the regulator and
heatsink.
(iv) Finally plug the I C.s into their sockets
The general procedure for each component
(a) Identify the part and its position on the board and insert it into the appropriate holes, bending the
leads if necessary (But see later) In the case of components with a number of pins, make sure that
they have all gone through their holes
(b) Hold the part in position - if you bend its leads to do this, do not press them flat onto the board as
this will make them difficult to cut and will encourage short circuits
(c) Solder all the wires on the 'green side' of the board and. if they are long, trim them with the side
cutters. No lead should stick out more than about 3mm
or W from the solder side
Some components need more detailed explanation:
3
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