HP 3457A - Page 224

b) Check the voltage applied to the relay coil. This can be done by connecting an oscilloscope
across
the
relay’s
coil
and
executing
the
following
command,
"TERM
REARSADV
AUTO:NPLC 0;AZERO OFF:DCV 30:SLIST xx". Where xx indicates the channel being tested.
This
will
set
up
the
voltmeter
to
continuously
cycle
(SETting
and
RESETting)
the
relay.
If
the
voltage
is
greater
than
2.5
volts
the
relay
should
be
working.
If
the
relay
does
not
respond,
replace the relay. If the voltage is less than 2.5 volts, check the drive circuitr
4) To test the drive circuitry for each relay requires checking the associated row and column
drivers
for
the
correct
signal
levels.
This
can
be
done
by
tracing
signal
levels
from
outputs
of
the
shift registers through the correct circuitry to the relay coil. Since relay drivers are active for only
10
milliseconds,
the
command
"TERM
REAR;SSADV
AUTO;
NPLC
0;AZERO
OFF;DCV
30;DISP
OFFSLIST xx" will continually cycle channel xx’s drive uitry allowing the signal levels to be
checked
with
an
oscilloscope.
The
table
below
lists
the
correct
output
of
shift
registers
U801
and
U802 for operation of each relay.
Table 8-4. Shift Register Outputs
Relay Condition Data u8s02 us01
| ceo 98070605 94030201 | a8a70605 a4030201
During Instrument
Measurement SFOF 0101 1111 1701 11141
SET
«800 FFS7 LAAT AEDS Ctet FI Tt
k801 F700 11411 0111 TROT TI8F
k802 FBOB F¥TT 1E77 1101 1011
k803 FODE PRET VET 1101 1110
K804 GEFF 0100 1110 19h CASA
K805 SF77 OV OT 2H14 StTt Bt941
K806 S7FD 0101 0111 1TH DARA
k807 SDFE 0101 1101 1171711110
k808 SBFB 0101 1011 TVA VHT
k809 GEFF 01001110 ea Po aA
RESET
k800 00c8 0000 0000 1100 1000
k801 0842 0000 1000 0100 0010
k802 0444 0000 0100 0100 0100
k803 0241 0000 0010 0100 0001
K804 5110 0101 0001 0001 0000
k805 4098 0100 0000 1001 1000
K806 4812 0100 1000 0001 0010
k807 4211 0100 0010 0001 0001
k808 4414 0100 0100 0001 0100
k809 1140 0001 0001 0100 0000
3457A Multimeter
8-61