Test Equipment - Cambridge Z88 Projects

APPENDIX A
TEST EQUIPMENT
LIST OF CONTENTS
Paragraph
1
2
Page No.
Introduction
32k RAM Pack Modification
A.1
A.1
PSU for Test Fixture
RS232 Loopback Test Plug
Card Tester Circuit Diagram for Slot
Tester and Bus Extension Tester
Slot Tester Test Head Circuit Diagram
Bus Extension Tester Test Head Circuit
Diagram
A.2
A.3
A.4
Fig No.
A.1
A.2
A.3
A.4
A.5
A.5
A.6
1.
INTRODUCTION
1.1
Appendix A provides the circuit diagrams for the Z88 test equipment. It
also provides information on the modification required to a standard 32k
RAM pack in order to transform it into the slot 2 test card.
2.
32k RAM PACK MODIFICATION
2.1
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:
Card Connector
32k RAM Chip
Al2 (pin 2)
A13 (pin 26)
A14 (pin 1)
A17 (pin 36)
A18 (pin 37)
A19 (pin 38)
wire to
wire to
wire to
A.1
100 F.S.D. (3k)
GREEN T RED
947OR
+VE
1k
93R1
968R
SW C
(>1
1N4148
N/C
OF470
SWA
1
0
2
1k
2*/.
[4k7[470k1470k14k7
Ilk
2*/.
2R2
2
REF -x502 LA
+VE
5
4 REGULATOR 1
SGS L200
30n
3
47k
30n
BC
184
BC
184
1k8
2*/.
10k
SWD
1k6
2*/.
PUS)-{ TO
BREAK
BC
184
MN INDIO
01 01
22k
2k7
1
OV
D.C. INPUT
SPECTRUM
MAINS ADAPTOR
SW B
/ 0 /
-VE
JACK
VE
-VE
BATTERIES
-VE
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.1 PSU FOR TEST FIXTURE
A.2
100k FROM Vcc
10
Tx (0/R)
2
Rx (HP)
30
RTS (0/P)
4
CTS(I/P)
50
-
60
GND
70
DCD (UP)
80
.5V via 470R
90
11\14148
1N4148
100k
FRAME (10M from 1) F0
©BC124
100k
BC184
BC184
—1
1 ir
680k -I100k
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.2 RS232 LOOPBACK TEST PLUG
A.3
.VE
(WHITE)
2850
100k
10M
BC214
3V0
BC214
30
10
Z88
ADAPTOR/
SPECTRUM
ADAPTOR
470
-VE
4 0--t
470
NOTES: I. 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.3 CARD TESTER CIRCUIT FOR SLOT CONNECTORS
AND BUS EXTENSION CONNECTOR
A.4
7
38
16
15
01
141
015
017
038
R38
R15
RI
O
3
0.1"
NOTES: 1. There is no R16 or D16 connected.
2. All resistors are 1 Mohm, all diodes 1N4148.
FIGURE A.4 SLOT TESTER TEST HEAD CIRCUIT DIAGRAM
A.5
SENSE CONNECTIONS TO
Z88 EXTENSION 8US
B1
B24
48-PIN CONNECTOR
BC214
NOTES:
1. Slot is in pin 18 position.
2. Side A of the connector is the component side.
3. All resistors are 1 Mohm, all diodes 1N4148.
4. GND goes to connector pin A14.
5. Sense connections are made to all except pins A14, B1 and
B24.
FIGURE A.5 BUS EXTENSION TESTER TEST HEAD CIRCUIT DIAGRAM
A.6