Driver gone duff ?

Long story short.
Romisen RC-F4, was fine then all of a sudden went to about 1/2 brightness, this is a single mode simple on off affair.
Will this have a driver to limit the current reaching the led ?
I did a search but nothing relevant found.
I installed tonight a new Q5 led thinking(hoping) that would sort it, unfortunately not, though it is a little brighter.
I really love this light, so is there any reason why I couldn't put a SSC P7-C in there if I cut down the heatsink, and used paste etc etc, with an appropriate driver, wouldn't need to drive hard for ace light with this led.
Any thoughts and comments gratefully received, thanks
tabetha

Bumpety bump for today, even guesses would be nice!!
tabetha

tabetha said:

Will this have a driver to limit the current reaching the led ?

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Yes, it will have a driver in it which regulates (limits) the current and voltage to the led.

Could be simple:
Sometimes drivers diminish output when they over-heat, or when the battery is low.

Could be the driver:
I had another driver that was only good for a few minutes on high in a p60 drop-in, but once I took it out it worked properly and would maintain high (or any other mode) until the lower voltage limit was reached.

Could be the switch, or anything else in the electrical path
An o-ring out of place preventing a solid connection, a problem with the switch that is limiting current, corrosion / debris on the contact points that is keeping the cell from making solid contact.

But since this worked for you before, perhaps just a weaker component, or a piece poorly soldered that's gotten worst, or swarf moving about. Could be age, could be fixable, double check any traces / connections if it's worth that to you.

Can you confirm current (ma) using DMM?

tabetha said:

...put a SSC P7-C

Click to expand...

Yes, it could be done, but should it? What output would you go for? You could direct drive it from a single 17670 but only for brief periods as that light is too small to disipate much heat.

tabetha said:

if I cut down the heatsink,

Click to expand...

- not sure what you meant by this, but if you add P7, you may want to add / incease the size of the heatsink if possible.
Basically, brighter light = more heat. Be very careful about over-heating the emiter, as you'll have noticed most P7 lights are sold with very large heads / heat sinking areas.
Or you can put P7 in and under-drive it just to get the improved efficiency if you have the extra P7's, but this would be a $20 emitter in a $14 light...

Lastly, P7 might mean you have to drill out reflector for it to fit through, I presume reflector won't have major issues (donut hole) with P7.

Thanks for that linger.
I will test the MA, when I collect my multimeter, as I accidentally left it there, but you have given me others things that I had not even considered, thank you for that, should be able to get to the bottom of this now.
It's odd been fine for years, me lad was using it and said the batteries are flat as it went a lot dimmer, so charged them up, no difference, even now on brand new AW cells.
Anyway thanks very much for the input, it is appreciated.
regards tabetha

Hi - looks like Linger has you on the right path. Here is a little feedback from end users on the DX site.

http://www.dealextreme.com/details.dx/sku.7999

It looks like regulator failures are not undheard of.

The P7 or an MC-E multi die will probably increase output, but will also shift the throw to more of a flood type beam.

You can wire it with 1 cell direct drive with the right LED, or even 2 cells DD / resistored into a 2S2P junction setup (like a Lux V design). Heat - well - goes with the territory. Nothing ventured, nothing gained.

Thanks for that, it's had to be put on hold, too many cars to fix, none my own!!
tabetha