TREX: Logbook Entries

TREX: aerosol Messages: 2 Entries..

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Entry Date Title Site Author #Graphics
224 Fri 21-Apr-2006Aerosol Laser Bad, return to factorywestmilitzer
214 Wed 19-Apr-2006Aerosol downwestmilitzer

224: aerosol, Site west, Fri 21-Apr-2006 15:51:20 PDT, Aerosol Laser Bad, return to factory
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
Attn: Robert Falbo

214: aerosol, Site west, Wed 19-Apr-2006 20:41:24 PDT, Aerosol down

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.