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    BOSCH IR Illuminator (PSU-IIR-36 & PSU-IIR-60) - Troubleshooting Guide

    Possible causes and solution(s)


    This is a comprehensive reference for diagnosing and resolving common issues with Infrared illuminators in security systems.

    • SR/MR illuminators, recommended Bosch PSU: PSU-IIR-36
    • LR/XR illuminators, recommended Bosch PSU: PSU-IIR-60


    Symptoms & Causes & Solutions


    Problem Cause Solution

    No output from unit.


    Unit not set up correctly










    Ensure illuminator is mounted and connected properly.

    Check if there is a red glow from the unit with the photocell window covered. - If no output, check voltage at PSU output.(See Top Tip at the end of this guide)

    If no voltage at illuminator, check for cable breaks and suitability. If voltage at illuminator is OK, check power pot and PC pot settings.



    Unit powers up but does not achieve required distance. Incorrect mounting, orientation or diffuser.

    Ensure illuminator is mounted correctly and in the right orientation.

    Check power pot is set to maximum and diffuser is correct angle to cover the camera field of view.

    This could also be due to poor camera sensitivity or incorrect camera settings. Consult camera manufacturers information.

    Unit switches on at wrong lux level.


    PC pot not adjusted correctly.








    Adjust the PC pot to set the lux level switching point.

    Turn clockwise to increase sensitivity (switch on in darker conditions) or anticlockwise to reduce sensitivity (switch on in lighter conditions).
    Ensure the sealing cap is replaced.



    Set illuminator for on/off control from PIR sensor. Incorrect wiring or pot settings.

    Set PC adjust pot fully anticlockwise. Connect telemetry wires, (blue and green), to PIR's Normally Closed relay terminals.

    Ensure relay contacts are normally closed for the illuminator to be off.
    When PIR triggers relay opens, and illuminator will turn on.

    Top tip (Check if LEDs are working).



    LEDs not emitting.












    Use a mobile phone camera to check for the red glow from the 940nm illuminator.

    Purple color in the camera indicates LED activity.

    Infrared wavelengths are at the extreme of human vision. Most humans can see a red glow from an 850nm illuminator. However, at 940nm it is very difficult to see.
    Only a very slight glow can be seen in complete darkness.

    This image shows a 940nm illuminator. Although the camera shows the light to be a purple color, it can be clearly seen that all LEDs are working even in full day light.

    Web browser continuously prompts for username and password. The persistent request for username and password in the web browser may be due to accumulated cache memory, leading to authentication issues.

    For Microsoft browsers:

    Navigate to browser settings.
    Select "personal preferences."
    Access the "cache" section.
    Click on "clear previous history, including passwords."

    IP integration failure with third-party equipment. The integration failure with third-party equipment is likely a result of incompatible firmware or software versions. Upgrade the firmware or software associated with the equipment to ensure compatibility and seamless
    Pulsing LEDs indicate potential power supply issue. Pulsing LEDs may indicate an insufficient or unstable power supply, causing disruptions in device operation.

    Check the power supply voltage to ensure it meets the device requirements.

    If the voltage is inadequate, replace the Power Supply Unit (PSU) with a suitable one to stabilize the power source and resolve the pulsing LED issue.

    For PoE models check the switch/injector complies with the required standard (af/at) and power budget has not been exceeded (for switch).


    We strongly recommend the use of regulated switch mode 24V DC PSUs for use with the illuminator range. In particular the Bosch PSU-IIR-35, PSU-IIR-60 and PSUIIR-100.

    Due to variations in mains voltage, we would not recommend the use of AC supplies with illuminator products.

    Version history
    Last update:
    ‎01-16-2024 09:42 AM
    Updated by: