My UF2100 (modded by E1320) has started flickering and change modes by itself

As you can se in the subject it has strted to behave strange.
Any ideas and can it be fixed easily?

Probably a loose contact somewhere, check for shabby solder joints.

check the switch if it’s tight
you can bypass it with a clip or a wire and see if it works without the tailcap

Most likely the switch. These have been iffy on a lot of ’2100s

Mine did this for a little bit. I had to tighten up the pill in the head of the light. no more problems since then.

Either the pill or the switch is loose. Most likely the switch is loose or dirty. Try and tighten the pill with some tweezers if that doesn’t work fill the switch with WD-40 loosen and tighten it several times let it dry overnight and that should fix the problem. If not send it back and I will fix it for free.

Good to see you back Eric, hope your well. :slight_smile:

Thanks, I am feeling a little better, but I still sleep a lot.

I have a temporary solution to the trembling in my hands, a cocktail of several drugs with bad side effects.

The doctors still aren’t sure what is going on, all they know for sure is my white blood cell count is extremely low (below 4000) and my hemoglobin levels are low as well. More blood work and a trip to a disease specialist are next on my list of things to do. I have tested negative for most of the common diseases except Lyme but the test I took for Lyme that was positive is supposed to not be an accurate version of the test so I will be getting a more accurate one done from the specialist.

Thanks everyone for the well wishes and kind words.

+1! We miss you E!


I messed with the switch a couple times….no luck

cleaned all the threaded contact areas……would work for a while then back to the same tricks

I finally found that the retaining ring holding in the driver and making its negative contact was just loose enough to let driver move a little and making and breaking contact.

I pressed that ring down a little and was able to get some solder from the negative ring on the drive the the retaining ring. Has been working great for 2 months now. No more flickering

whoa, nice to see you back e1320! i was wondering where you been. didnt hear about your condition till now. but i really do hope all is well. our prayers go out to you man.

one of my 2100’s started doing this as well. from what i have read, it was a bad switch problem. and those above post are good suggestions, i will try the tightening and wd40 trick.

and millerman, that might be the solution to the 2100! i dont quite understand what you did though since im not savvy with flashlights hahah

I have 3 of them and sloved all of my problems by replacing the switch with the help of some of our members here.

Hope you get your problems figured out soon!!!

Here is a picture

I have made well over 100 of these mod lights, I don’t use the ring to hold the driver in it is soldered in so unless the solder broke loose that is not the problem.

The switch however has been problematic from the very beginning and I warned people even with the stock driver the switch is inadequate.

Here is a link to the original thread, there is much discussion about the switch problems on there.

This is how I fixed the problem 100%