Model2000 Series DewPrime
Dew
Point Hygrometers
----------Troubleshooting
and
Repair----------
Table 6-2. Fault isolation.
Recommended Checks
and
Replacement
Not all
three
power
supply
voltages,
+5V, +lSV,
and
.
-ISV,
are
present.
This is probably caused by a failme in one of
the
power
supplies
or a poor cable connection from
the
transformer
to the main PCB (connector J2).It can
also
be caused by an overload on one of the power
supply
regulator circuits. Tum the equipment off and, in a
few
minutes,
tum
it back on. This causes the
overload
protection circuits on the power supplies to reset
and,
if
the
overload
was
temporary
,
the fault
will
clear.
Sensor mirror
does not
heat
above
ambient
temperature
during
a
self-standardization
cycle, but
operates
on
dew
point
readings.
Measure the voltJlge at TP2 during the
Automatic
Balance Control (ABC) cycle and while the
ABC
LED indicator is on steady, as during
the
self-standardization cycle.This
voltage should be
±0.5
volt.
Mirror temperature cools
below the
actual
dew
point
and
large amounts
of dew
or
frost
builds up on the
mirror
surface.
Press
the MABC key to place the instrument in the
self-standardizatio
n mode and
clean
the mirror surface with
isopropyl
alcohol. Make sure no
detergents are
allowed on
the mirror
surface
.
If
trouble
persists,
it
may
be caused
by
dirty optics.Clean the optics with
isopropyl alcohol
and
a
pipe cleaner
.
Clean optics are indicated by a
voltage
drop
of
greater
than 5V
acros
s R51
.
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