Kipp&Zonen Brewer MkIII - Manual (Page 17)

MKIII SERVICE MANUAL 12
2. Check Temperature
Observe the temperature of instrument (TE). If the Brewer temperature is less than 0 degrees
Celsius, the lamp may be too cold and may not fire. If this is the case, the Standard Lamp may be
turned on for a few minutes to warm the Mercury lamp.
3. Check Lamp Voltage and Current
There is the possibility of a lamp failure. Perform an AP (A/D voltages printout) test. If the Mercury
Lamp current is 0.0, and the Mercury Lamp Voltage is near 15 volts, then the lamp is probably bad.
Measure the voltage across the lamp, pins 6 and 9 on P111. (Reference Figure 10.6-2.2). It should
be approximately 0 volts with the lamp off (B0) and 13 volts with the lamp on (B1).
4. Mercury Lamp Replacement
To replace the bulb, loosen the two thumb screws (item 6, Figure 10.6-2.2) and carefully withdraw
the lamp holder. Take care not to touch the new lamp with bare hands. Ensure the lamp is tight in
its socket and cleaned with isopropyl alcohol after replacement.
The quartz-halogen lamp should also be checked at this time, as blackening of the glass could
reduce the amount of HG light which is passing through it to the foreoptics. Re-assemble the HG
lamp by reversing the above steps and test the lamp with B1 and HG commands.
5. Check Micrometer Position
If the lamp is working fine, and light can be seen in the Viewing Ports, then the position of the
micrometer should be checked. Remove the “Spectrometer” cover and check to see that the
micrometers are in the correct position as indicated in the Final Test Record, and on the Log Sheet
taped to the Spectrometer cover. If the Micrometers are not where the Log Sheet indicates, they
should be adjusted manually and an HG test attempted again.
6. Attempt a Standard Lamp Test
If the test still fails, the problem could be in a misalignment of a component in the Spectrometer, a
problem in the slit mask, or a fault in the PMT or counting circuitry.
Attempt a standard lamp test. The standard lamp has a much higher intensity and does not depend
on the position of the micrometer and slitmask as much as the mercury lamp test.
If the standard lamp test operates correctly, the SL printout should be examined carefully to see if
any characteristics have changed. If the dark count has increased significantly, this may be an
indication that the alignment has changed and may require a mirror adjustment. Check to see if any
of the intensities or ratios have changed, which may indicate that the optics have deteriorated, or
the PMT performance or counting has degraded. If the standard lamp test results appear to be
normal, then KIPP & ZONEN should be contacted before proceeding.
7. Measure High Voltage
If the standard lamp test is not operational, then it can be assumed that there is an optical failure,
or a PMT failure. If the mercury lamp test is normal while the standard lamp has failed, this usually
indicates a problem with the lamp or the circuitry that controls the lamp.
The high voltage should be measured using a voltmeter and looking at test point E16 on the Main
Electronics board. There should be a voltage between 2.5 volts and 5 volts, which has been
factory set (see final test record for the setting), and should not be adjusted. This voltage is equal