Sinclair ZX81, Assembly Instructions Manual, Page: 6 / 43

these locate Serious damage will result if the long screws are inserted in the wrong holes.
(iii) Locate the board on the pillars in the case, make sure the jack sockets are behind the holes in the
side, and screw it into the case. Only two holes need screws in them at this point - Fig. 11 tells you
which two; the others are for the case bottom fixing. Since the screws will have to form their own
threads in the plastic, they may be a bit stiff to turn the first time therefore it is essential that the proper
screwdriver should be used. An ordinary flat screwdriver will almost certainly slip, and may cause
damage to the circuitry when it does. See the list of tools given in section 1
(iv) Turn the case the right way up again, peel the protective paper off the back of the keyboard and stick
it into its recess in the moulding (the keyboard is self adhesive - no extra glue is necessary). It would be
as well to position the'keyboard correctly the first time, to avoid damaging it by continual relocating.
Locate the top edge of the keyboard against the top edge of the recess, and stick it down carefully,
working gradually towards the lower edge. Have a dry run first if you are in any doubt. Do not try to stick
the whole surface down in one go.
(v) After checking that the keyboard connections are still securely in place, locate the bottom half of the
case and screw it to the top with the remaining five screws. Finally the rubber feet plug into four of the
recesses, over the screw heads. Fig. 11 shows the location of screws and feet.
(vi) Give the computer a final check, and start using it. . . .
8. COMPONENT LIST
Note that some components are marked on the circuit board, but shown as "not used" in this list. Do
not put anything in these positions.
(a) Resistors.
All resistors have four colour bands: the fourth may be gold or silver.
No. Value Markings Comments
R1 10K Brown Black Orange
R2 680 Q Blue Grey Brown
R3 Not used
R4 18K Brown Grey Orange
R5 330 Q Orange Orange Brown
R6 2K2 Red Red Red
R7 470 Q Yellow Purple Brown
R8 470 Q
R9 470 Q
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