c.
The ATN (ATTENTION) line and the
discrete gates of U9 can be checked using the following state-
ments:
1.
To force the ATN line LOW, send the HP-IB command: SEND
7;
CMD 0
BASIC Program:
10 SEND
7;
CMD
0
2.0
END
RUN
When the ATN line
(U9 pin
1
and 2) goes LOW, pin
25
of the HP-IB MCU should go HIGH
and the MCU should drive pin 9 of U9 LOW. Also, the HP-IB MCU will output a LOW to pin
9 of U6.
2.
To force the ATN
lime HIGH, send the HP-IB command: RESET
7
BASIC Program:
10 RESET
7
U)
END
RUN
When the ATN line (U9 pin
1
and 2) goes HIGH, pin
25
of the HP-IB MCU should go LOW
and the MCU should drive pin 9 of U9 HIGH. Also, the HP-IB MCU will output a HIGH
to
pin 9 of U6.
d. Transceiver IC U6, which drives the HP-IB DATA lines can be checked for Output using Signature
Analysis (Refer to the Signature Analysis Troubleshooting section which follows Signal Tracing.)
To check U6 data lines for Input, use the following statements:
BASIC Program:
10 SEND
7;
CMD
85
20
SEND 7; CMD 170
30
GOT0 10
RUN
Check that all of the data lines toggle and the inputs match the outputs.
HP
5334B
-
Service Manual
8-69
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