Romisen RC-M4 problem

I got this single mode flashlight with P4 emitter from DX 2 weeks ago. The other night while I was using this Romisen RC-M4 for approximately 2 straight minutes it suddenly flickered and then the beam went steady but already very dim. I compared its beam to my L2D Q5 and it is slighty brighter than the L2D on low.

I tried using another pair of fresh CR123 primaries, check the tailcap switch, clean all contacts but the beam was still very dim.

What do you think is wrong with this light? Thanks in advance.

does the head unscrew?
if so, check to see if there is something that prevents the bare LED from contacting the metal (is it?) reflector.
it normally is plastic, or mylar.

csshih said:

does the head unscrew?
if so, check to see if there is something that prevents the bare LED from contacting the metal (is it?) reflector.
it normally is plastic, or mylar.

Click to expand...

Thanks, csshih.

Yes, the head unscrewed. I also uncrewed the aluminum reflector and clean the threads of both the reflector and the circuit module. Here is the pic.


After reassembling the light is still dim.

Keeping the bare module out and no reflector, try connecting it to a single cell directly if it works then you're breaking the conduction somewhere, I'd say most likely in the swtich. If it's still dim then you've got a bad driver. Get a new pill the R2 is noticeably brighter.

qwertyydude said:

Keeping the bare module out and no reflector, try connecting it to a single cell directly if it works then you're breaking the conduction somewhere, I'd say most likely in the swtich. If it's still dim then you've got a bad driver. Get a new pill the R2 is noticeably brighter.

Click to expand...

It works when directly connected to a single cell. I have also tried connecting the negative end of the battery inside the tube to the tube body, still dim. So the switch is ok.

I guess I got a bad driver. Thanks for your help, qwertyydude. Yes I will get R2 drop-in module.

Wait it works full power on one cell? If it does than you're not making full contact. Try sanding the tube where the outer spring contacts the battery tube since the threads on the head side is anodized that is the only point of electrical contact between the module and body.

qwertyydude said:

Wait it works full power on one cell? If it does than you're not making full contact. Try sanding the tube where the outer spring contacts the battery tube since the threads on the head side is anodized that is the only point of electrical contact between the module and body.

Click to expand...

It works but still dim when directly connected to one cell.

Have tried sanding the edge of the tube that come in contact with the outer spring of the module, and still no improvement.

Thanks qwertyydude.