Test Equipment Howto D.I.Y.

Cambridge Computer never supplied any test equipment. Here is an opportunity to build these circuits and have a complete Z88 Test Set.

Primary Names

The Primary names used here are listed on page 3.2 of the Service Manual. They are different to those used later on the circuit diagram. To prevent confusion, this table list the differences. In this Test Equipment section, primary names are used as the headings.

ItemPrimarySecondaryNotes
1

Sinclair Spectrum Mains Adapter

  
2

Z88 Cased Unit Test Fixtures

 FIGURE A.1 PSU FOR TEST FIXTURE 
3

Special Test Box

(with separate power supply)

FIGURE A.3 CARD TESTER CIRCUIT FOR SLOT CONNECTORS AND BUS EXTENSION CONNECTOR

(underneath the Z88 under test).

The original design split this up into 3 sections

  • Test head
  • Card Slot Tester Test Head 
  • Bus Extension Tester Test Head

The Bus Extension was never used in the end, so only the Card Slot Tester and Test Head need to be built.

4 - 6

Test Card Connector for SKT2, 3 & 4

FIGURE A.4 SLOT TESTER TEST HEAD CIRCUIT DIAGRAM 
7

Test Card for Peripheral Expansion Connector

FIGURE A.5 BUS EXTENSION TESTER TEST HEAD CIRCUIT DIAGRAMThis connector was never used, so this connector may be discarded.
8

RS232 Termination Connector

FIGURE A.2 RS232 LOOPBACK TEST PLUGI have just been using a plug linking 3 pairs of pins together. I wonder whether this circuit will offer any benefits?
9

Standard RAM Pack

32K RAM Pack 
10

Special Modified 32K RAM Pack

Now 1M RAMThere were no 1M RAM Packs available when the manual was written.
11

128K EPROM Test Program Pack

128K EPROMThe test software will be available here for download.
12

240 V Variable Transformer

(with flying mains socket attached) 
13

Adapter Test Box

This is the same as Item 2, - Z88 Cased Unit Test FixturesItem number duplicated.

 

 

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