Surefire A2 acting weird?

NYCblue

Newly Enlightened
Joined
Dec 30, 2004
Messages
43
Location
New York City
Hey guys,

When I depress the tailcap on my surefire A2 for the incandescent it has been giving me a dimmer light, then a few seconds later it comes on full brightness. Or it will come on normally fully brightness, and on the next press it will just be a dim incandescent and so on. New batteries don't make a difference either. Anybody have any idea whats going on? Any remedies?

thanks
 

dano

Flashlight Enthusiast
Joined
Aug 11, 2000
Messages
3,881
Location
East Bay, Cali.
Mine (a newer rounded body model) will do this when the batteries are low, and the light goes out of activation. Also, I'd clean the contacts around the rear of the light, where the tailcaps "tabs" make contact.

-dan
 

Planterz

Flashlight Enthusiast
Joined
Dec 14, 2005
Messages
1,162
Location
Tucson, AZ
The A2 has some soft-start circuitry. It eases current into the bulb when you first turn it on, rather than pump the full amount of juice right up front. This means less shock to the filiment, which improves the bulb life and reduces the chance of it blowing when you turn it on (which is when most bulbs blow).
 

Perel

Newly Enlightened
Joined
Jan 24, 2006
Messages
36
My A2 tailcap is missing one of the three inside tabs, and it does the same thing when turned to one position in particular. It becomes a tri-level light: LED, unreg incan, reg incan. Kinda neat really, though you really have to mash it in for reg incan and the tailcap doesn't work at all if it's not rotated exactly right. Yes, I'm getting it fixed.

Has me wondering if there's some non-destructive way to mod a tailcap to do this reliably - it's really handy to be able to check the battery status while still having reg incan available. Plus it's really striking to compare the dim, yellow beam I'd have without the regulation with the bright, white beam it provides..

Yeah, when the tailcap is fixed I'll probably just leave it "normal".. but it would be interesting to find a slightly more robust way to keep this extra functionality, or at least be able to turn it on/off.

FWIW, I think the unreg incan occurs when the resistance from the tailcap is somewhere between 0 and 10 ohms. Anyone with some resistors handy want to see what happens if you take the tailcap off and short the battery to body with, say, a 5 ohm resistor? I know that 0 ohm = incan on and 10 ohm = LEDs only.. but what about an in-between value? This has some interesting modding potential.
 

beezaur

Flashlight Enthusiast
Joined
Apr 15, 2003
Messages
1,234
Battery brand makes a difference. Some, including myself, have had problems with Battery Station. I only get 15 minutes of incan runtime in both of my A2s with Battery Station batteries. However, it isn't always the batteries. Since I switched back to SureFire batteries, I still get a "sluggish" start. I suspect with mine it is a combination of contacts that aren't as clean as they could be and partially depleted batteries.

Scott
 

js

Flashlight Enthusiast
Joined
Aug 2, 2003
Messages
5,793
Location
Upstate New York
You have some extra resistance somewhere in your tail cap, or it has a broken contact, or you have a bunch of defective batteries.

I talked about this in my The SF A2 thread.

The "unregulated" incan is actually only possible BECAUSE of the regulaton circuitry. If you took it completely out of the circuit and direct-drove the MA02 lamp on 2 123's, it would BLOW. It is a about a 4 volt lamp. When you have the unreg level it is because the LVR3L regulator is turning on because it sees enough voltage across its terminals, but then turning off because the voltage falls below the level at which it will turn off. Then the battery voltage rises again, and it turns on again, and so on, many many times a second. THIS is the low-level incan.

If you have this, and your batteries are fresh, then the problem is with the tail cap. Clean the three contacts inside the tail cap with a nice soft cotton pipe cleaner. And be careful not to get grease from the threads on the contacts. Also clean the butt end of the light body.

A broken tab can also cause problems, so if you don't have all three, then call SF CS and get a new tail cap.

Check out the link above for pics of the inside of the tail cap and other information.
 

g36pilot

Enlightened
Joined
Dec 22, 2005
Messages
220
And put a voltmeter on your batteries to check condition. I recently had a partner condemning his brand new G2 purchased on my recommendation. He was given two of my fresh spares and it worked great.

Since we didn't have a meter with us, his new box of SF 123s were tested with my single cell QIII to find five wouldn't ignite the lamp.

As a precaution, I now meter each battery that goes into my duty spares carrier. Off duty, I'm not a careful as plenty of spare batts & lights are usually handy.

Let me add that my A2 doesn't like Battery Station 123s. After an incan runtime of 11 to 14 minutes it acts just like yours. With Sure Fires I get the published incandescent runtime then the incad behaves as yours due to normal incan regulation design. The LEDs continue to work normally.
 
Top