AI Prime 16 HD Unusual Failure Mode (Missing Color Channels) & Solution

[DaJMasta]

I've been using an AI Prime 16 HD over a 10G tank in my rack for some low light corals and anemones, and a week and change ago, I had a strange fault: it would come on and act normal, but was all green. On closer inspection, it was that the light appeared green because both blue channels seemed to have burned out. The unit could be reprogrammed and setup as normal and reported no errors or error codes, but the light was green, and the output was substantially lower than normal.

So I went on to find a replacement, paired it up with the app, tested it out, installed it, and then got a different failure mode: the lights looked really purple, like the white channels hadn't been enabled but clearly red and blue had been. Now this light just tested fine minutes earlier on the same profile I've been using for ages, so what could it have been?

The power supply.

The power supply still reads 24V unloaded, but when loaded down, the voltage drops, and since the Prime 16 HD isn't monitoring its input voltage/current (or at least doesn't react to it being insufficient), it boots up and configures fine, goes to turn on the channels, drops to a lower voltage operating mode, and then just sort of sits there, going through the day with some channels off. I did observe my original unit get some normal looking lighting (not sure if every channel was good, though) towards the end of the day, when the consumption should be low (and the loading low, so less dragging down of the power supply voltage), so presumably it can recover fine and it has to do with minimum voltages for the converters used to drive the LEDs, but when I swapped power supplies to the one that came with the new unit instead of the one installed, it was fixed, and the same is true now on my old unit. It's odd to me that the channels that worked were different between different units, and were consistent through power cycling - it appears to be deterministic based on the unit (maybe hardware revision) rather than random, and they are running on the same firmware.

I've got proper measurement stuff for this, so I'll try to elaborate on the failure mode soon, but since I didn't see it documented elsewhere, I think it's an important thing to mention:

If your AI Prime 16 HD starts missing channels and the color looks really funny, especially if only during bright parts of the day, it may not be the light that is bad, it may be the power supply.

 

[DaJMasta]

It was actually really easy to demonstrate, so here it is:


Even 2 Volts under the rated input can cause channels to start dropping out, the farther down, the more channels.

 

[oreo54]

It was actually really easy to demonstrate, so here it is:


Even 2 Volts under the rated input can cause channels to start dropping out, the farther down, the more channels.

Thanks. Yea power supplies are the usual first thing to check if it is more than one or so diodes.
Each channel driver takes the incoming voltage and will control it (drop voltage) till the current pull is at its set point.
Of course when its too low there is nowhere to drop it. If the string is long you could get to the point where the turn on voltage is too low.

Red, green channels in particular probably have a low v(f) on those strings so will probably light.
The longer ones will drop out first.
So say your ps is supposed to put out 24v but only manages 21v under "load" and at the same time you have a driver "loss"of 2V you really only have 19V out.
At around 3v that would only be enough for like 6 diodes. If the string is longer than that it will either not light or be VERY dim.

As to the differences between lights..???. May just be diode lot variation tweaking the V(f)

As to my brief understanding of this.

 

[DaJMasta]

Yeah, sounds about right. I'm more used to the large strings which run substantially higher voltages and need like 40V+, but with this little fixture, each string is probably well under the 24V input, and just has a buck converter to stay efficient.

With no input voltage monitoring, though, the light can't tell and can't report it, and I was surprised the margin was so low.

 

[oreo54]

V(f)'s shouldn't be much more than 15V on the big channels i.e white, blue and RB BUT I do not remember if they used some 5w class diodes.
I have no comment on how voltage would get redistributed.. LOL. or the effects of fans, logic circuits.
Way beyond my pay grade.

You could probably crack open the ps and replace the power caps which most likely have failed.

AI Prime 16 HD ** NEW**​

 

[08TRDOFFROAD]

Having this issue with my prime HD. Just ordered a new PS on Amazon. Crossing my fingers this fixes my issue. I will post to update when it arrives.

 

[Jmp998]

Thanks for posting this, I'm sure this will help someone save $$$ replacing a power supply instead of an entire light. I would not have thought of power supply as the issue with only a subset of the LEDs failing.

 

[08TRDOFFROAD]

Here is the PS I ordered.

https://www.amazon.com/gp/aw/d/B08MTLLLGJ?ref=ppx_pt2_mob_b_prod_image

Will update once I know it works. Should be here tomorrow (thanks amazon!)

 

[08TRDOFFROAD]

Thanks for posting this, I'm sure this will help someone save $$$ replacing a power supply instead of an entire light. I would not have thought of power supply as the issue with only a subset of the LEDs failing.

It has probably already saved me $$$! Was super frustrated when I noticed the issue last night and was going to my LFS this afternoon to pick up a new light. Now holding off to see if the $17 new supply I ordered fixed the problem.

I just checked and I am getting normal light output during ramp up at low intensity very early in my program, my guess is as i get into the daylight portion (higher wattage demand) I will lose all but my 6 royal blue leds, which was what I was experiencing last night when I ran it through the accelerated version of my light cycle.

 

[08TRDOFFROAD]

It has probably already saved me $$$! Was super frustrated when I noticed the issue last night and was going to my LFS this afternoon to pick up a new light. Now holding off to see if the $17 new supply I ordered fixed the problem.

I just checked and I am getting normal light output during ramp up at low intensity very early in my program, my guess is as i get into the daylight portion (higher wattage demand) I will lose all but my 6 royal blue leds, which was what I was experiencing last night when I ran it through the accelerated version of my light cycle.

Here is the PS I ordered.

https://www.amazon.com/gp/aw/d/B08MTLLLGJ?ref=ppx_pt2_mob_b_prod_image

Will update once I know it works. Should be here tomorrow (thanks amazon!)

Thanks for posting this, I'm sure this will help someone save $$$ replacing a power supply instead of an entire light. I would not have thought of power supply as the issue with only a subset of the LEDs failing.

I can verify the PS I ordered works with the Prime HD. It also resolved my issue! I get nice smooth changes of intensity now as I run my accelerated light cycle. Maybe I will record a video to show the symptoms I was experiencing with the bad power supply (dropping channels, flickering, etc) if it might be helpful to others.

Thanks @DaJMasta for posting this and your YouTube short (what I originally stumbled over in my search to repair the light)!!!!

 

[DaJMasta]

Glad it helped! I was surprised that this was the failure mode for a power supply going bad and was happy to find that the solution was so straightforward.