YORK YK — When Conducting the Optical Sensor Test the Flip Dot Does Not Turn Red.

The display shows the message in the manual's exact wording: When Conducting the Optical Sensor Test the Flip Dot Does Not Turn Red. The manual prints this wording in one form only, so this is the single variant of the message. It appears when the flip dot fails to turn red while the optical sensor test is being carried out.

The manual states the meaning plainly: the flip dot does not turn red during the optical sensor test. The red flip-dot indication that the test should produce does not appear, and the manual's solution treats this as a fault to be worked through step by step — from the way the test is performed, to the smoke application and wiring, to the sensors themselves.

• The optical sensor test is not being conducted according to the instructions on the can of smoke.
• The can of smoke is not directed at the sensor with the black grill.
• The wiring to the base of the sensors, or the wiring at TB1 on the 031-03958 board, is installed incorrectly.
• A sensor — with the white grill or with the black grill — whose LED does not light.

1. Determine whether the optical sensor test is being conducted according to the instructions on the can of smoke.
2. If the test is not being conducted correctly, repeat it following the instructions on the can of smoke.
3. If the test is being conducted correctly, make sure the can of smoke is directed at the sensor with the black grill.
4. If the can of smoke is not directed correctly, direct it at the sensor with the black grill.
5. If the can of smoke is directed correctly, remove the 120 V AC and remove both sensors.
6. Verify that the wiring to the base of both sensors is installed as shown in the wiring diagram provided in the kit.
7. Verify that the wiring at TB1 on the 031-03958 board is installed per the same wiring diagram, and correct any wiring error you find.
8. Reinstall the sensor with the black grill, apply 120 V AC and repeat the test; the LED on the black-grill sensor should light.
9. Remove the 120 V AC, reinstall the sensor with the white grill and reapply 120 V AC (the manual notes this resets the sensor), then repeat the test; the LED on the black-grill sensor should light, and the system is working properly.
10. If an LED is not lit, install a new sensor with the white grill and repeat the optical sensor test after the replacement.
11. If the LED is still not lit, install a new sensor with the black grill, again repeating the optical sensor test after the replacement.
12. If the problem is still not solved, contact PTS.

The manual's solution gives no separate reset instruction; the reset it describes is a reset of the sensor, performed inside the check sequence: Then remove 120 V AC, reinstall the sensor with the white grill and reapply 120 V AC (this will reset the sensor) After this the optical sensor test is repeated, and if the LED on the black-grill sensor lights, the system is working properly.