1. Introduction To Fault Diagnosis
Section 4 is intended as a guide to fault diagnosis and repair. It is written for repair staff who are familiar with standard fault-finding procedures and who have the requisite test equipment available. The table below lists the minimum required test equipment and materials.
| Equipment | Specification / Manufacturer |
|---|---|
| Frequency Meter | General Purpose |
| Oscilloscope | Rise time 100 nanosec |
| Digital Multimeter | General purpose |
| Known good LED display unit | Cambridge Computer |
| Known good keyboard unit | Cambridge Computer |
| Mains Adaptor | Cambridge Computer |
| Superglue | Open market |
Three types of board are in circulation, Issue 3, 4 and 5. Only a small number of Issue 3 boards are in existence. They differ from Issue 4 boards in that certain components have been manually wired in. In Issue 4 boards, the printed circuit has been amended to accommodate these components. The relevant components are listed below:
| Resistors | R80, R81, R82. In addition R23 (l00k) has been relocated in parallel with D9. |
| Capacitors | C31, C32. |
| Transistors | T25. |
| Diodes | D28, D29, D30. |
| Preset potentiometers | RV2. |
On Issue 3 boards, resistors R52 and R75 have been removed from the circuit and leave gaps. There is also a gap where R23 has been removed in order to be relocated in parallel with D9.
The issue 5 boards have been designed for foreign electromagnetic standard compliance. The differences have to be developped.
The following information has been copied from an A2 size Cambridge Computers Z88 Circuit Diagram Drawn by F.I. 4.4.87 Checked by A. A. R. 13.4.87
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