80-Bus News


July–August 1984, Volume 3, Issue 4

Page 26 of 43

pin ‘D’ of an existing key with the new key’s ‘D’ pin and ensure that the distance from the existing pin D to the new key’s pin D is exactly 0.75″; mark this accurately on the line which you previously drew. Holding a new key, mark the positions of the other 3 pins carefully. Centre punch each point lightly and drill all 4 holes.

Key drilling guide

Insert the new key through the frame and check that the pins go through the holes. If all is well, carry on, otherwise get your eyes checked! The cursor control keys are normally fitted on the same level as the Space bar and the easiest way of locating the pin positions is to use a setsquare and draw lines down from the corresponding keys in the row immediately above. When all 40 holes have been drilled, breathe a sigh of relief and drill 6 more! These are the mounting holes for the resistors and are positioned as in the sketch.

I.C. and new resistor locations on keyboard

* 1pin 1 of each i.c.
x – – – – x1 mm holes
I – – – – I2K2 resistor
II – – – II22R resistor
III – – III1K resistor

Page 26 of 43