Review: ThruNite TN42 LED Searchlight

Yes these 3 dies remain glowing when the light is off. I looked again the led in moonlight mode and I can confirm that 4 dies are lights Ok. So strange…

Wolfdog,you misunderstood!! Easy asked to turn light on and see if the same [3 out of 4 dies on] thing happens?!! :person_facepalming:

I emailed HKJ….Hopefully some of the builders and modders on here will chime in. They may have an answer…my answers are unrelated to flashlights!!!

Well, I must wait for the knowledge and advice of some of the gurus in modding and electronics. Hope they can help me with this issue…

If all four dies are lighting at power on, I would suspect the e-switch wires maybe pinched or shaved and bleeding power to the emitter, not enough to fully light them when the light is off. There is always a bit of power going to the MCU via the e-switch, hence parasitic drain. There is a mess of wires between the inside of the head and reflector, they pass thru the shelf into the driver below, the ones I modded had sharp edges around this pass thru hole. I’m just guessing, but that is where I would look, first. Maybe remove the e-switch bezel and button and see if wiggling the wires kills the power going to the emitter, might even be the switch contacts on the back of the switch themselves? Then TN42 does have that lighted Blue ring when powered on.

Again just a guess, I haven’t had it happen to me…yet. but I am intrigued!!!

Hi Kawiboy, thanks for your answer. I´ll try to remove the e-switch bezel and see what happens.

Max

I do not know exactly how that light is designed, but a weak glow in the leds may not be a problem. Modern leds need very little current to glow.
I possible try measuring the tailcap current with the light off, then you can see if the drain is significant for battery life.

Hi HKJ, yes the flashlight seems to perform as should be. But the rare thing appeared suddenly yesterday! It means that something happens…

A couple pic’s to see what your up against!

I removed the e switch bezel with no results so far. A new thing noted is that this dim glow is not constant. I mean that if I look close to the light magnified on the reflector I see some kind of blinking.

Driver and Switch ribbon, very close to the ground. And a row of resistors!!!

You could remove the driver cover screws, pop the driver out and look at the switch ribbon for frays, maybe move it around a bit and re-assemble, and see if the emitter stops glowing? I wish I had it so I could monkey with it!!! :smiley: :+1:

I have some promissing news! I removed the bezel and pulled out a bit the wire ribbon of the e-switch and Voila! the glowing dissapeared to the naked eye. Then I push the flashlight agains my face to close all the surrounding light. It seems that the led still glows a bit but less than a GITD hand of a wrist watch.

I have to say that Kawi boy was right. it seems that the wires of the e-switch were causing the strange issue and I guess that the remainig almost undetectable glow that remains on the led (I repeat it only can bee seen in total darkness and a when the pupils dilate enought) is the famous parassitic drain. but correct me if I am wrong.

Thanks you all to help me to solve this annoying trouble and I hope it will serve to other that may experiment the same issue.

Again sorry for my english.

Woo Hoo Shorting! Well not woo hoo for you! But I seem to remember having something similar, but it was that blue ring power on thingy, it would come on when ever it wanted too? Never figured it out, so I ripped the guts out of it and put a 4S LD-2 M2 3amp Linear driver in it pushed that LED to the MAX and never looked back!!! :beer:

I dislike Boost drivers anyways, their sooo temper -mental!!! :smiley:

You can get ya some liquid rubber, I use Dynatex Brush On Electrical Tape and try to cover where ever you have that short, just let it dry completely or the vapors will fog your reflector if not dried fully!

Yeah found out the usual way, the hard way! :wink:

That means there is a tiny leakage current, maybe due to moisture or contamination on the electronic circuit or maybe because the circuit is a bit warm (Electronic parts have higher leakage current when warm).

The 4 leds will not turn on at exactly the same voltage, that is probably the reason that only some of the are glowing (It can also be leakage current inside the led, that prevents some of them from glowing).

Unfortunately here in Argentina all of this wonder materials that you have in almost all hardware stores are not available but I will try to find some thing similar. :nerd_face:

I am glad you guys figured it out!!

I am basing this assessment in comparison with mine.

I do NOT believe the minimal light that remains in your light is from parasitic drain.It must still be tied in w/ your electrical problem.

I went in a closet that was completely dark. Turned the light on ML. Turned it off. 100% of the light was gone immediately and I waited a minute or so for my eyes to adjust more and there was ZERO illumination coming from the emitter.

You certainly made progress and as I posted w/ MY DIFFERENT problem,Keep the batteries OUT of your light until you are ready to use them! :wink:

If it’s barely noticeable —just lock out the light manually ( unscrew battery tube slightly from the head) when not in use—I usually do this with all my E switch lights to assure no parasitic drain or accidental powering on

Yes, I will do that. Thanks you all again for your valuable help

I got my TN42 Holster from HKE today. A definite improvement over the strap!

The snap does not connect[I knew that from another member]. I guess they did not do any tests w/ a TN42 inside of it for measuring purposes!

The velcro still makes it secure.The TN42vn just happens to be in my rotation tonight! :+1: Perfect timing.