Bosch FAS‑420‑TP Series - Flashes - Error: Internal Voltage Monitoring; Flashes - Error: Fan Voltage Monitoring

Aspiration smoke detector LSN improved Maintenance | en 103
Bosch Sicherheitssysteme GmbH Operation guide 2020.04 | 6.1 | F.01U.029.275
– Using a multimeter, measure the operating voltage (DC) of the aspirating smoke
detector.
– The measurement value must be between 14V and 30V.
Restore the correct power supply.
– Display board faulty
– Disconnect the power from the unit.
– Remove the display board's connection cable from the motherboard.
– Restore the operating voltage and run the unit for a few minutes.
– If the display board is faulty, the malfunction will no longer occur.
Replace the faulty display board.
– Motherboard faulty
– You will need a second motherboard to make this diagnosis.
– Disconnect the power from the unit.
– Replace the motherboard with a new motherboard of the same type.
– Restore the operating voltage and run the unit for a few minutes.
– If the motherboard is faulty, the malfunction will no longer occur.
Replace the faulty motherboard.
8.2.2 2 Flashes - Error: Internal Voltage Monitoring 2
In operation with two detector modules, both LEDs flash. When troubleshooting, the following
steps should be carried out in the specified order.
– Operating voltage too low
– Using a multimeter, measure the operating voltage (DC) of the aspirating smoke
detector.
– The measurement value must be between 14V and 30V.
Restore the correct power supply.
– Detector module faulty
– Disconnect the power from the unit.
– Replace the detector module incl. connection cable with a new module of the same
type.
– Restore the operating voltage and run the unit for a few minutes.
– If the detector module is faulty, the malfunction will no longer occur.
– If you are using two detector modules, repeat the process with the second detector
module.
Replace the faulty detector module.
– Motherboard faulty
– You will need a second motherboard to make this diagnosis.
– Disconnect the power from the unit.
– Replace the motherboard with a new motherboard of the same type.
– Restore the operating voltage and run the unit for a few minutes.
– If the motherboard is faulty, the malfunction will no longer occur.
Replace the faulty motherboard.
8.2.3 3 Flashes - Error: Fan Voltage Monitoring
In operation with two detector modules, both LEDs flash. When troubleshooting, the following
steps should be carried out in the specified order.
– Operating voltage too low
– Using a multimeter, measure the operating voltage (DC) of the aspirating smoke
detector.
– The measurement value must be between 14V and 30V.