# Faulty/defective Lumen Light **URL:** \ **Category:** Lights\ **Created:** [November 18, 2020, 10:39pm UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597 "2020-11-18T22:39:50Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![diveexplorer](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/diveexplorer/32/17493_2.png) [@diveexplorer](https://discuss.bluerobotics.com/u/diveexplorer)\ **Post date:** [November 18, 2020, 10:39pm UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/1 "2020-11-18T22:39:50Z")
Hello and good day… Need some assistance or guidance regarding our BlueROV2 (Heavy config) with 4-lumen lights V2. It is quite new, only been like 6 dives and none of those below 10 meters as of yet. We noticed today that one of the lumen lights was not as bright as the other three. It did not go to full power. It does not seem that the light has been flooded. This light is the last one in the daisy chain connection. Could it be defective? Or something else? What would be the first thing, and the smartest thing to do to check it? Best regards to you all. ---
**Author:** ![ploa](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/ploa/32/7021_2.png) [@ploa](https://discuss.bluerobotics.com/u/ploa)\ **Post date:** [May 21, 2021, 5:41am UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/2 "2021-05-21T05:41:46Z")
Hello all, we are facing exactly the same issue with the same configuration (brand new). I was wondering if anyone has found any solution or has a suggestion on that. Cheers ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [May 21, 2021, 5:49am UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/3 "2021-05-21T05:49:16Z")
Daisy-chaining the lumens connects them in parallel, so if the last one in a chain isn’t as bright as the others there’s either excessive resistance in the last cable, or the lumen itself is damaged or defective. If you want to you can try opening it to see if there’s any water inside the casing, or damage on the PCB or wires. Before doing that I’d suggest taking a photo of all the lights on so you have a record of the issue. From here, please contact [support@bluerobotics.com](mailto:support@bluerobotics.com) to and mention this thread. They should be able to to sort out a repair, replacement, or refund 🙂 ---
**Author:** ![ploa](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/ploa/32/7021_2.png) [@ploa](https://discuss.bluerobotics.com/u/ploa)\ **Post date:** [May 21, 2021, 6:40am UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/4 "2021-05-21T06:40:22Z")
Thank you for the quick response! I will go through that in the next days and I post any finding here. ---
**Author:** ![ploa](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/ploa/32/7021_2.png) [@ploa](https://discuss.bluerobotics.com/u/ploa)\ **Post date:** [June 2, 2021, 5:53pm UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/5 "2021-06-02T17:53:37Z")
Well, I went through the lights but I couldn’t locate the problem. No water inside and the resistance from the previous light in the chain was minimal. Just in case, I check also the NTC resistor which seemed fine. Currently onboard, I don’t have an oscilloscope on hand to check if the PWM is correct or for more in-depth analysis. ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [June 3, 2021, 1:24am UTC](https://discuss.bluerobotics.com/t/faulty-defective-lumen-light/8597/6 "2021-06-03T01:24:11Z")
Can’t really be an issue with the PWM for a single light in a daisy chain because they all read the same input signal. There’s either a resistance issue in the power supply (power wire, ground wire, soldered connections, etc), or the electronics of that light are faulty (possibly a bad clock, or tuned to the wrong PWM range).