D4K front AUX LEDs missing blue channel - can it be fixed?

[fogus]

Just got my first D4KTI. Straight out of the box, I believe the front AUX LEDs are missing their blue channel (green and red seem fine).

I set it to “rainbow” beside another brand new D4V2 light and there is never any blue light from the D4KTI, while the D4V2 happily cycles through blue, cyan, purple, etc. The D4KTI skips blue entirely (front AUX turns off). I went through both brightness levels and even on high brightness, no blue channel. I went through the other solid colors, and every one that needs a blue channel has nothing. All eight of the AUX LEDs behave the same way.

I emailed Hank with a couple of videos to get his take.

I am handy with a soldering iron. Can I fix it or should I try for a replacement?

[INeedMoreLumens]

Take the bezel and optic off and take a picture of the Aux PCB and post it here.

[fogus]

Here you go.

[fogus]

Different angle:

[fogus]

I also have a multimeter. I’m guessing those 4 smaller solder joints near the center are the RGB+ground. Can I ohm them out to something on the back? I’m going to try testing ohms to a few points here.

[fogus]

I get about 900 ohms across the blue resistor. Good connection between the blue wire solder joint on the AUX PCB and the blue resistor.

[fogus]

Here’s exactly what I mean:

[INeedMoreLumens]

Solder connections to the aux PCB look good.

The only other thing I can think of to do, is to check the functionality of the Blue using the continuity check.

Set your multimeter to continuity:
Touch your black probe to the Black contact point and your red probe to the Blue contact point:

If it lights up, the blue lead probably popped off the driver side in shipping.
If it doesn’t light, a new Aux PCB should resolve the issue.

[fogus]

Continuity as in the “continuity test” (the one that beeps)?

[INeedMoreLumens]

Yes

[fogus]

And this needs to be done with the battery in and in a mode that would illuminate the blue AUX light?

And can you explain what this is accomplishing, electrically? Am I shorting the blue supply to the ground? Is that a good idea?

[SammysHP]

No, you do all those measurements without a battery. The suggestion was to use the multimeter as a current source. (I’d use the diode check mode, though.)

[fogus]

I have an adjustable power supply. What should I set for volts and amps?

[SammysHP]

You don’t want to use that. Or does it reliably supply let’s say 1mA?

[fogus]

It is a Rockseed RS605P with resolution down to 1mA.

But the amps is just a safety factor. It’s the volts that I really need to know.

[fogus]

Here are some more photos of the existing solder joints.

[SammysHP]

@fogus

But the amps is just a safety factor. It’s the volts that I really need to know.

It’s an LED, the volts don’t matter (as long as they are high enough). Your PSU can’t regulate the current quickly enough. Use the multimeter in diode check mode.

[fogus]

I have a Fluke 115. I do not know how to put it in diode check mode. How do I do that?

[SammysHP]

Turn the selector to the diode symbol.

[fogus]

Ok. And red on blue and black on black, and then see if the blue LEDs turn on? How fast should it act?

What is this going to do, electrically? Apply some voltage, acting like a power supply?