Sinclair ZX81, Assembly Instructions Manual, Page: 8 / 43

!C4b uPD2114LC-1 18 pins
REG 7805 5 Volt regulator
TR1 Z T X 3 1 3
TR2 Z T X 3 1 3
D1-D8 * 1N4448 Colours: Yellow, yellow, yellow, grey
or 1N4148 Yellow, brown, yellow, grey
or 1S44 2 Yellow bands
Some diodes may have their number printed on them instead.
D9 Not used
X1 CDA 6 BMC 3 lead ceramic filter
(e) Other components
Modulator type UM1233
3 off 3 5rnm jack sockets for power, ear and mic.
2 eff 40 pin 1C sockets
Eitae"r. 2 off 24 pin 1C sqckeis. „ . . .
or
• T off 24 pin and Z off 18 pin |
C
sockets
KB1 5:\way keyboard connector
KB2 8~Way keyboard connector
Modulator trim (black card)
Ready made flat keyboard
Aluminium heatsink
4BA nut, bolt and washer for fixing regulator and heatsink
Printed circuit board
2 Case halves
4 Rubber feet
7 Self tapping Pozidriv screws - 3 Black (long), 4 Yellow (short)
9. POWER SUPPLY
If you wish to use your own power supply with the ZX81, it should conform to these specifications -
D.C. only -positive to the tip of the 3.5mm jack plug. Need not be regulated, but should be well
smoothed.
Voltage - between 12 volts maximum and about 8 volts minimum (depending on smoothing) when on
load.
Current - not less than 600mA, or 1 2A of the printer is to work from the same supply.
10. SERVICE
We will repair your completed ZX81 kit f o r a fixed fee of £10 00 We cannot assemble your kit for you,
nor can we start work until the fee is received. In exceptional cases, say if the t.C.s have been
damaged by being put in the wrong way round, we may ask for an additional payment.
On the other hand, if the trouble was due to faulty components supplied by us we will reiui.j the full
service fee. We strongly advise you, therefore, to be very certain that you have checked the computer
thoroughly \oi mistakes before returning it: see also the hints in section 6.
If you do return your ZX81, pack it well and enclose a note giving your name and address, and
explaining the symptoms of the trouble and any tests you may have done. Please return to this
address:
Sinclair Research Service Dept.
Chesterton Mill
French's Road
Cambridge
CB4 3NP
® Sinclair Research Limited 1981