|224||Fri 21-Apr-2006||Aerosol Laser Bad, return to factory||west||militzer|
|214||Wed 19-Apr-2006||Aerosol down||west||militzer|
21Apr06 The laser for the 9012 particulate counter is bad and needs to be returned to the factory for repair. This was determined after discussion with Robert Falbo who is the expert on the sensor. He suggested two tests (Note it is safe to work on it because the laser is self contained. 1) check exhaust flow. The flow goes through the laser first, through some filters, pump, and flow meters eventually to exhaust which is by the needle valve / nipple mounted on the pump. This needs to be roughly 3liters/min. This test indicated that the pump is working. The pump it is driven off a PWM technique which ramps the speed up or down depending upon feedback from the flow-meter and counter. This is why it sounds as if the pump starts up slowly and eventually kicks in. That had fooled me into suspecting a clog or bad pump. 2) check current-shunt voltage for the laser. The laser's health is monitored across TP1 (on the small 'perpendicular' pcb attached to the end of the laser, and to TP3 (ground, on the main laser electronics board). These test points can be identified by the red and black insulators around them respectively. The correct voltage should be ~800mV; anything above 1V indicates a bad laser. With this unit, the voltage was 1.6 dropping to 1.25 as the pump ramped up. Robert confirmed it is bad and gave us a return authorization # Return / Contact Information Met One Instruments Inc. 1600 Washington Blvd. Grants Pass, Oregon 97526 541-471-7115 Attn: Robert Falbo RA#20764
19Apr06 The aerosol particulate counter has been reporting bad data since the 4/13. Values now are almost all zeroes, with some integer values. Tech support from MetOne sent the manual, which really doesn't say much, and the windows configuration/monitor software which I installed on the panasonic. At the site, this software failed to communicate with the counter even though procomm was seeing the raw messages. At one point I did manage to grab it's help printout during startup: Tomorrow we'll bring the sensor down to the base 20Apr06, ~9:15PDT Removed aerosol from tower. At the base it appears to work, the pump starts slowly, but runs. It could be that the pump, or filters are clogged because of the slow startup. Other attempts to communicate with it via 'particomm' software still failed.