2. 32k RAM PACK MODIFICATION
In order to modify a standard 32k RAM pack to produce a test pack for use in System Test, certain wiring must be connected from the chip to the card connectors as follows:
32k RAM Chip | Card Connector |
A12 (pin 2) | wire to A17 (pin 36) |
A13 (pin 26) | wire to A18 (pin 37) |
A14 (pin 1) | wire to A19 (pin 38) |
FIGURE A.1 PSU FOR TEST FIXTURE
NOTE: Output is as follows depending on the position of switch A:
- Position 1 - 2.8V
- Position 2 - 3.8V to 4.6V
- Position 3 - 4.6V to 6.1V
FIGURE A.2 RS232 LOOPBACK TEST PLUG
NOTES:
- 1. The principal aim is to check that every wire is connected to the 9-way socket including the 10M between pin 1 and the socket frame.
- 2. For the serial port to work, both CTS and DCD must be high.
FIGURE A.3 CARD TESTER CIRCUIT FOR SLOT CONNECTORS AND BUS EXTENSION CONNECTOR
NOTES:
- 1. The 'test head' of both the slot connector tester and the bus extension connector tester use the above circuit.
- 2. The LED is connected between pins 4 and 5 on the test connector test head.
- 3. A 0.4 mm thick spacer is installed between the connector side of the pcb and the plastic housing. This builds in a deliberate spacing so that the test pcb will only make contact provided all 38 connector springs are positive.
- 4. The Z88 mains adaptor is connected for the slot connector tester and the Spectrum adaptor is connected for the bus extension tester.
FIGURE A.4 SLOT TESTER TEST HEAD CIRCUIT DIAGRAM
NOTES:
- 1. There is no R16 or D16 connected.
- 2. All resistors are 1 Mohm, all diodes lN4148.
FIGURE A.5 BUS EXTENSION TESTER TEST HEAD CIRCUIT DIAGRAM
NOTES:
- 1. Slot is in pin 18 position.
- 2. Side A of the connector is the component side.
- 3. All resistors are 1 i10hm, all diodes lN4148.
- 4. GND goes to connector pi n A14.
- 5. Sense connections are made to all except pins A14, B1 and B24.