Background: The 105% indication and reading is Rosemount’s way of showing an error message; it was presumed that everyone in the opacity business would recognize that there is no such thing as 105% opacity and that it would instantly mean ‘analyzer failure’ to anyone observing it on the monitor’s display. It was also an easy way to get the milliamp output signal to rail high at about 21 maDC.

Components affected: LCW (liquid crystal window), lamp (bulb), power supply (SLB, Stack LON Board), G-64 LON Board, interconnecting cabling, & temperature.

The fault alarm (105% opacity) can come from any of the following:
[1] failing bulb/lamp or lamp power supply
[2] failing LCWs or LCW power supply
– VLTH [volts too high]
– LMPF [lamp failure per software algorithm]
[3] loss of Eshelon communications (LON)
[4] failing wire harness (to lamp or LON communications)
[5] failed calibration
[6] corrupted software on the Stack LON Board
[7] failing detector board (±15 vdc power comes from the SLB)
But not:
[a] actual stack opacity conditions (high opacity)
[b] misalignment
[c] dust on barrier window and/or corner cube
[d] steam that has changed phase to vapor

Call us to help you diagnose this. Please provide the following:
- model number
- age of LCWs
- age of bulb/lamp
- reference voltages (8) (under Cal, Reference Voltages)
- current ‘run’ voltages (4) (under Data, Volts)
- temperature