19
TROUBLESHOOTING
The following steps should be performed if flame is not detected:
NOTE: Wear protective filtered lenses when viewing flame.
1.
Check scanner wiring for breaks and proper connections.
2.
Look down the sight pipe.
— Scanner should have an unrestricted view for all firing conditions.
— The flame’s primary combustion zone (first 1/3 of flame) should be within the scanner’s
field of view for all firing loads.
3.
Clean the scanner lens with a glass detergent or glass cleaning agent which contains no abra-
sives. After cleaning remove all cleaning films with a soft lint-free cloth. (Some cleaning films
may reduce or filter UV).
4.
Measure voltage across scanner terminals.
— Between terminals 14 and C there should be 70 VAC pulses of 6 microseconds (use oscillo-
scope).Between terminals L and C there should be 200 to 250 VAC for units manufactured
before 1994. For later units, there should be 130 to 150 VAC.
5.
Scanner operation can be checked by aiming the scanner at a source of ultra-violet radiation,
(lighter or propane torch). The meter on the associated control should indicate flame.
6.
Check to see that an external selector switch is connected to the associated control’s sensitivity/
threshold select or scanner enable terminals.
7.
Reposition scanner so it is properly aligned for best flame signal.
8.
If the scanner still does not indicate the presence of flame (DC voltage on Flame Signal Meter)
replace the UV tube and repeat steps 4 through 7.
