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3 - Troubleshooting
30
Pro
g
ram out
p
ut on,
volta
g
e and current full
scale then check
out
p
ut volta
g
e
Troubleshoot Fuse
divider and am
p
lifie
r
circuit
(
R393/394,
U305
)
Disable the
p
rotection
feature b
y
simultaneousl
y
p
ressin
g
the 0 and 9
ke
y
s,
p
ress the ^ ke
y
until the dis
p
la
y
reads
"No Protect Off",
p
ress
the U
p
Arrow to dis
p
la
y
"No Protect On" then
p
ress ente
r
FS Prot off and
Out
p
ut OK?
Calibrate unit
Yes
No
FUSE si
g
nal OK?
Check FUSE si
g
nal
U305B-7
(
a
pp
rox.
+2.8V with 20V out
p
ut
)
No
Problem ma
y
be
defective A2 or one of
the volta
g
es to A2
(
Vmon, Imon
_
H,
Imon
_
L, Imon
_
P
)
> its'
bias volta
g
e +5Vs
Yes
Out
p
ut V >
p
ro
g
rammed
value?
No
Go to "Troubleshootin
g
Hi
g
h Out
p
ut Volta
g
e"
(
sheet 12
)
Yes
Figure 3-1 Sheet 6. FS Indicated but Fuse OK