Emisar D4 problem (low brightness do not turn on - video)

d_t_a · 2018-08-24T08:17:17.000Z

My Emisar D4 (quad-Nichia) seems to have developed a problem.

It was working normally before.

Then was testing the tailcap current of several 18650s that I own.

After testing, I tried using the Emisar D4 normally again, but it was not functioning normally.

When I first inserted a battery, normally the Emisar D4 should do a quick 2 blinks, but now it DOES NOT blink.

After inserting the battery, clicking the button once (should turn on at the max regulated brightness, which is 0.35A or around 150 lumens), but no light comes out from the flashlight. Tested this several times with different batteries. Upon first inserting the battery and clicking once (which should turn on at the max regulated mode), no light comes out of the flashlight.

Tried another time to hold a couple of seconds (which should turn on the flashlight in Moon mode), but no light comes out.

Then I tried to press & hold the button down, which now causes the flashlight to turn on at some higher brightness mode. It seems to function normally from that medium brightness mode to the max brightness mode. But if I ramp downwards, then the light will go "off" at the lower brightness level (instead of going down to Moon brightness level).

It seems the lower brightness levels are not possible anymore.

To diagnose further, I checked the tailcap current while clicking the button in various ways... see video below.

What could be the problem?

As of now, the only way is to press & hold to turn on at a higher brightness level, then click once to turn off. Now clicking once turns on at that higher brightness level. "Lower brightness levels" seem to have no light.

d_t_a · 2018-08-24T15:16:18.000Z

When first inserting battery, the D4 also does not have the signature 2 blinks…

So far the only way to turn it on is to hold the button down until it goes to some low brightness mode (but not Moon)…

ChrisGarrett · 2018-08-24T17:56:53.000Z

I’d be asking the question ‘what did I fry, or blow up on my light’s driver board (or switch) by doing the current tests I just did?’

You obviously ‘broke’ something, but I don’t design driver boards/switches, so I can’t say.

Don’t do it again, however.

I couldn’t see past your hands, so I couldn’t see your leads resting on the light, but could you have shorted something out? Things appear to be a little funky, the way you’re holding things.

Chris