FIRMWARE
SIGNATURE
ANALYSIS-LOGIC
SUPPLY
SHIFT
REGISTERS
I.
Purpose
To diagnose component failures in the logic supply shift registers.
II.
Equipment required
A. Tektronix SA 501 Signature Analyzer (or equivalent)
B.
CPU Board Extender (067-1 028-00 kit)
C. Logic Board Extender (067-1 028-00 kit)
D.
Two TM 500 Flexible Extenders, Tektronix Part Number 067-0645-02
Ill.
Electrical conditions necessary to perform test
A. CPU,
ROM
and RAM functional (verified by power-up self test)
B. Serial outputs from CPU board functional. Verify with addressable latch test.
C.
Startlstop test point (TP1401 functional). Check S/S test point (TP1401) for pulses approximate-
ly 5.5 ms apart.
IV.
Setup
A. PS 5010 (extend boards with power off)')
1. Place logic supply board on extender.
2. Place CPU board on extender.
3.
Set mode jumper (J1320) as shown.
[c]
Signature mode
4. Set runlforce data jumper (J1220) as shown.
B. Signature analyzer
Connect to CPU board and set as follows:
Threshold
=
TTL
Start
=
I
Connect to CPU board sls test point (TP1401)
Stop
=
Connect to CPU board sls test point (TP1401)
Clock
=
I
Connect to CPU board
@2
test point, 51 11 1, pin
2
(clock)
Gnd
=
Connect to ground test point (TP1011)
V.
Measurements
Start by checking
+
5
V
signature (pin 14, U1841) to verify correct setup. Take measurements on
shift registers starting with U1841. then U2041.
If
inputs
(I)
to either chip are correct and outputs
(0)
are incorrect that chip may
be
defective.
I
Data
in
(from
CPU
board)
u
Serial data
Logic
supply
filter
board
I
1
Fig.
9-8.
CPU
board
3391
39
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