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TROUBLESHOOTING & REPAIR M102E/M501 TRS
(Addendum to M101E Manual - P/N 04740 Rev A)
10.1.2. Fault Diagnosis with Test Functions
The Following table supercedes Table 11.2 of the M101E Manual - P/N 04740 Rev A.
Table 10-2: Test Functions - Possible Causes for Out-Of-Range Values
TEST
FUNCTION
NOMINAL
VALUE(S)
POSSIBLE CAUSE(S)
STABIL
≤1 ppb with zero
air
Faults that cause high stability values are: pneumatic leak; low or very unstable
UV lamp output; light leak; faulty HVPS; defective preamp board; aging PMT; PMT
recently exposed to room light; dirty/contaminated reaction cell.
SAMPLE FL
650 cm
3
/min
± 10%
Faults can be caused by: clogged critical flow orifice; pneumatic leak; faulty flow
sensor; sample line flow restriction.
PMT
-20 TO 150 mV
with zero air
High or noisy readings could be due to: calibration error; pneumatic leak; light
leak (improper assembly); aging UV filter; low UV reference output; PMT recently
exposed to room light; light leak in reaction cell; reaction cell contaminated; HVPS
problem.
It takes 24-48 hours for a PMT exposed to ambient light levels to return to normal
functioning.
NORM PMT - -
Noisy Norm PMT value (assuming unchanging SO
2
concentration of sample gas):
Calibration error; HVPS problem; PMT problem; UV reference problem; UV lamp
problem.
UV LAMP 2000 -4000 mV
This is the instantaneous reading of the UV lamp intensity. Low UV lamp intensity
could be due to: aging UV lamp; UV lamp position out of alignment; faulty lamp
transformer; aging or faulty UV detector; dirty optical components.
Intensity lower than 600 mV will cause UV LAMP WARNING.
LAMP RATIO 30 TO 120%
The current output of the UV reference detector divided by the reading stored in
the CPU’s memory from the last time a UV Lamp calibration was performed. Out
of range lamp ratio could be due to: malfunctioning UV lamp; UV lamp position
out of alignment; faulty lamp transformer; aging or faulty UV detector; dirty
optical components; pin holes or scratches in the UV optical filters; light leaks.
STR LGT 40-100 ppb
High stray light could be caused by: aging UV filter; contaminated reaction cell;
light leak; pneumatic leak.
DRK PMT -50 - +200 mV
High dark PMT reading could be due to: light leak; shutter not closing
completely; high pmt temperature; high electronic offset.
DRK LMP -50 - +200 mV
High dark UV detector could be caused by: light leak; shutter not closing
completely; high electronic offset.
HVPS
≈ 400 V to 900 V
Incorrect HVPS reading could be caused by; HVPS broken; preamp board circuit
problems.
RCELL TEMP 50ºC ± 1ºC
Incorrect temperature reading could be caused by: malfunctioning heater; relay
board communication (I
1
C bus); relay burnt out
BOX TEMP
ambient
+ ~ 5ºC
Incorrect temperature reading could be caused by: Environment out of
temperature operating range; broken thermistor; runaway heater
PMT TEMP
7ºC ± 2ºC
constant
Incorrect temperature reading could be caused by: TEC cooling circuit broken;
High chassis temperature; 12V power supply
IZS TEMP
(OPTION)
50ºC ± 1ºC Malfunctioning heater; relay board communication (I
1
C bus); relay burnt out
PRESS
ambient
± 2 IN-HG-A
Incorrect SAMPLE pressure could be due to: pneumatic leak; malfunctioning
valve; malfunctioning pump; clogged flow orifices; sample inlet overpressure;
faulty pressure sensor
SLOPE 1.0 ± 0.3
Slope out of range could be due to: poor calibration quality ; span gas
concentration incorrect; leaks; UV Lamp output decay.
OFFSET < 250 mV
High offset could be due to: incorrect span gas concentration/contaminated zero
air/leak; low-level calibration off; light leak; aging UV filter; contaminated
reaction cell; pneumatic leak.
TIME OF DAY Current time
Incorrect Time could be caused by: Internal clock drifting; move across time
zones; daylight savings time?
52 05514 Rev A1