Thermo Scientific 7450, Operating And Maintenance Manual

Page: 82 / 120

7007452 CryoMed Freezer 9-5 Thermo Scientific
Troub
le
sho
ot
in
g Guid
e
C
h
a
m
ber te
m
p
erat
u
re erratic
1). Hig
h
LN
2
pres
su
re
2). C
h
a
m
ber th
er
m
o
co
u
p
le
mo
u
n
ti
n
g
3). C
u
st
o
m
er adj
u
st
ed P
ID
param
eter
s
4).
T
/C
s
h
orted or in
correct
ly
pos
it
io
n
ed.
1). Veri
fy
t
ank
pres
su
re (reg
u
lat
or:
22# n
o
m
in
al
)
2). Verif
y
t
h
er
m
o
co
u
p
le h
ead ou
t of
m
oun
ti
ng
tu
be ¾
in
ch
3). Verif
y
correct P
ID v
alu
es
i
n
Ser
v
ice – T
h
erm
al
Co
ntr
o
ll
er
m
e
n
u
4).
T
es
t f
o
r s
h
ort an
d v
er
ify
pos
itio
n
.
1). R
eplace tan
k
/regu
lator
2). A
d
ju
st
th
er
m
o
cou
p
le
h
ead
p
o
sitio
n
.
3). Set cor
rect PID v
alu
es
or
reset to f
actor
y
d
ef
a
u
lts i
n
t
h
e
Serv
ice m
enu
(Mak
e n
o
te
of
probe calib
ration
v
alu
e
s prior to
reset to f
actor
y
def
a
u
lts or re-
calibrate pro
b
es
as
n
eces
sar
y
)