Kipp&Zonen Brewer MkIII - Manual (Page 26)

MKIII SERVICE MANUAL 21
5 TEST RESULTS OUT OF SPECIFICATION
Whenever any diagnostic tests are out of specification, (SL, HG,DT,RS,) the following should be
done or considered.
1. If the deadtime has increased or decreased significantly, the High Speed Amplifier board
may be defective, the slitmask may have become misaligned, or a ground in the instrument
wiring may have become resistive. High moisture levels inside the instrument may also
cause abnormal deadtime results.
2. A test lamp may have deteriorated to the point where tests are affected, and the lamps
may require replacement. They can be inspected as mentioned in the previous sections,
and replaced if necessary.
3. The optical surfaces within the zenith prism may have become smudged with a fingerprint
or may have become dusty over a period of time. The prism should be cleaned, referring to
section 6.2.
4. The micrometer may be "sticking" and not in its exact location after a measurement or a
test. It should be inspected and the drive mechanism carefully cleaned with tissue and
isopropyl alcohol.
5. Dark count is a convenient characteristic to monitor as it is printed out in many tests and
measurements. Dark count changes may be the result of moisture, changes in the slit
mask, PMT, high Voltage, or counting circuitry.
6. When the dark count of an instrument changes, or becomes erratic, a slitmask Run-Stop
test should be done to see if there are any changes in the slitmask circuitry. If this does not
give any indication of the problem, there may be a ground somewhere which has become
resistive, and it should be checked.
7. The High voltage test can be done, and the results compared to those in the Final Test
Records.
8. Generally speaking PMT problems are not field repairable.
9. Desiccants should be changed at regular intervals. The frequency of desiccant change
depends on the climate. Desiccants will require changing much more frequently in humid
environments. Alternately the humidity indicator can be used to indicate that desiccant
needs changing – desiccant should be changed if the moisture index provided be the
electronic humidity sensor is greater then 10 or if the paper indicator for 40% humidity is no
longer blue. Desiccants can be removed and dried overnight at approximately 60 degrees
C if necessary.
If these checks fail to locate the problem, KIPP & ZONEN should be consulted as to further
investigation.
5 TEST RESULTS OUT OF SPECIFICATION