HP 3490A - Page 191

Remow
A13U3, Set RA-
TIO
$itch to EXT
REF
10 V. Ois@nnect
dc stan-
dard
from
INPUT and con-
net to EXT
REF lerm-
Monitor
wltag€
at A13
test
poinr
C
whil€ applying
EXT
REF wltages
below:
EXT REF TPC
+20V
+13.6ro+14.3V
,20V
-
13.6to-
t4.3V
Select
Test
4.
Set RATIO
switch--
to
INT
REF.
Conn4t
dc shndard
to
INPUT
terminali
and
apply
-
10.0000
V. Display
sbould b€
+
(x).9995
I
{'lO
counts
+
dc
atandard
qrorl.
With
@nditions
sme
as
previous
test,
ch4k
logic
lewls 6
follows:
T6t Point
Lowl
D
LOW
U5
pin
12
HlcH
U5
pin
11
HtcH
lNote 2l
Ch*k Input Prot@tion
Circuit A13cRt-4,
A13Fl1-3.
Afrer rep6ir,
go
to
next
step.
Refer
to
Gdffal Trouble-
*r@ling Tree, Fig.7.4,
min 34904 man@1.
Replace
A13l
Dis@nned
from
EXT
R
net ro
lNPt
Apply
-
10.00
TEST
4. Shc
tqmimls. Wil
rO EXT
REF
should be 0O.r
NOTES
l. A dc standard
and a
dc wltreter
are
required for
these
check;.
2. Logic HIGH=+2.4V
ro
15V
Logic Low
=
0 to +
0.6 V
3.
Perform
Ratio
Adiustment Proce-
dure after @mpleting
repairs.
54904-D-loaa
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