Troubleshooting Fenix L1T v2.0

What I would like to know

How can I troubleshoot my light or did I wreck it permanently?

Light

Fenix L1T v2.0

Current status

Sometimes it turns on but only on high and not low. Twisting the bezel does not switch it to low. The majority of time it doesn't even turn on at all.

What I did to cause the problem

Took the head off of my L1T and put it on my P3D running on 2 RCR123s. The light was bright but got hot quickly. I think I may have wrecked the driver board.

Did you use new batteries?
Did you clean all contact surfaces?

Let's see, you ran a 3 volt head with 7.4 volts. You can typically run those heads with a single li-ion and no long-term effects. Two li-ions is another story entirely though; that would have been extremely over-driven. I would not at all be surprised if it did permanent damage to the driver and LED.

That really is a bummer; the L1T v2 is a nice light!

Is the high still full brightness?

I read this and tested the with the head on a p3d tube with the following results:

On low

• AA sends 20 mAmps and light doesn't work
• CR123A sends 10 mAmps and light is dim

On high

• AA sends 20 mAmps and light doesn't work
• CR123A send 1.2 Amps and light is bright with a whine

I don't have a fresh AA to test with. What does the above results indicate?

bla2000 said:

I read this and tested the with the head on a p3d tube with the following results:

On low

• AA sends 20 mAmps and light doesn't work
• CR123A sends 10 mAmps and light is dim

On high

• AA sends 20 mAmps and light doesn't work
• CR123A send 1.2 Amps and light is bright with a whine

I don't have a fresh AA to test with. What does the above results indicate?

Click to expand...

Is that with one or two CR123s? Off the bat I would say that the "boost" abilities are blown hence the low voltage of the AA not doing much of anything. If you are testing with only one CR123 then that would change things up a bit.

I was testing with a single CR123A.

Sounds like
A) you fried the driver by putting way too much voltage through it...

or

B) your AA's are dead.

---

I'm leaning towards A) with this one. The L1T is a 3v max head. You put ~7.4-8.4 volts through it... Guess what, it wasn't designed to handle it, and is subsequently fried...

greenLED said:

Did you use new batteries?
Did you clean all contact surfaces?

Click to expand...

Never mind me - I missed the part about the 2xli-ion.

Your driver is toast. Take advantage of the opportunity and mod the light.

If I've fried the board then is this DX board a suitable replacement which was recommended in TorchBoy's driver list thread? If so then I will have to learn to mod if I want to fix it. Previously I was thinking about replacing the led but after opening the head I never got around to buying the solder station.

The standard checks to run through first...

Check all AA batteries are good - ideally fresh batteris to be sure.
Make sure all contact surfaces are nice and clean - the points the battery contacts the head and tail, and all the connections between the sections of the light.
Make sure the switch is okay and tight - they can work loose sometimes and will cause intermittent problems with turning on and so on.

See if that does anything to help - a lot of problems can be caused by things working loose or connections getting dirty.

If that doesn't get you anywhere, it sounds like the problem is that something blew when you ran it on the other battery tube - feeding such a voltage to something that is not designed for it can damage the circuitry and the LED - the fact that it got so hot and bright doesn't bode well as that is a sure sign of it being hugely overpowered.
If that is the case, I think you are probably looking at a new light - repairs are just not cost effective.

I am rather fond of the L1T as a light though, and have been carrying one as EDC for a fair while and it is still going strong - nothing has yet tempted me enough to upgrade from it (bah to all the fancier UI's and so on) though I am wandering if there is going to be an LT10 appearing anytime soon.

With a fresh AA it always works but only on high. I've lost low. Currently that is better than nothing but perhaps I'll try replacing the board and led in the future.

Weird, so at least part of the boost circuitry must still be intact. A single CR123 wouldn't direct drive an emitter at 1.2A and a single AA wouldn't even light up the LED without a boost circuit. Maybe general mode not working is from dirty threads? Not sure though, I'm really just guessing here.

I cleaned the threads and still no low. Here are results testing with my DMM:

L1T - AA

• low = 40 mA
• high = 2.2A

P3D - RCR123

• low = 19 mA
• med = 60 mA
• high = 181 mA
• turbo = 430 mA

I added the P3D reading to hopefully show that my DMM is getting an accurate reading when it returns 2.2A for the L1T on high. Are the reading for the P3D accurate?

I checked my older P3D with RCR123s, that originally came with a Rebel. It now has an XP-G R4. Here's what I got on mine. It appears the circuit is different on my low and med, but high and turbo are the same as yours. I have a Fluke DMM.

low------.02A
med-----.07A
high-----.18A
turbo----.45A

I have the Leatherman version of the L1T V2 and got these readings with an Eneloop. The emitter on this one has been changed to an XR-E R2.

low----.14A
high----1.66A

Thanks. Your P3D reading are almost the same because the differences are:

• low = 1mA
• med = 10mA
• high = 1mA
• turbo = 20mA

I guess my DMM is accurate and my L1T is sending 2.2A on high. btw, my P3D has a Q2 bin XRE so it is quite old.

Once the head is open how can I access the driver to replace it? I would like to learn how to mod. I've searched the forums for driver replacement of p3d and l1t heads but didn't find anything.