Please help me fix my erraticly switching on/off flashlight!!

I have a nice(budget) LED flashlight on the body it has CREE Q2 LED Power 240 Lumens Digital Torch, nicely made, decent brightness. Uses a single 18650 and runs forever, it has 2 modes: 1 click high 2 clicks low.

Recently though it will switch on/off randomly or won't power on when I switch it on with the tail switch UNLESS I give it a solid smack against my leg. Its not the battery(even with a fully charged known good battery it will exhibit the issue), not the battery contacts or power contact on the tailcap threads. Generally one solid hit and its good till I switch it off, other times it comes and goes continuously.

It's been driving me nuts, I use it on my MTB bicycle and I'll be riding down a hill smacking the light trying to make it work, almost wiped out this evening. :fail:

Seems its the click switch, if I screw off the tailcap when it exhibits the not switching on nonsense and I use a screwdriver to short the battery negative to the body it switches on every time, clearly its the switch that's not great, the switch is in the tailcap.

Do I just need to replace the little micro switch inside the tailcap, how does that fit in with the dimming circuit?

Mountain Bloke said:

riding down a hill smacking the light… almost wiped out this evening.

Click to expand...

Dude! I'm worried about you. Throw that broken $8 light in the trash, before it kills you, and treat yourself to something more durable.

Mountain Bloke said:

I have a nice(budget) LED flashlight on the body it has CREE Q2 LED Power 240 Lumens Digital Torch, nicely made, decent brightness. Uses a single 18650 and runs forever, it has 2 modes: 1 click high 2 clicks low.

...

It's been driving me nuts, I use it on my MTB bicycle and I'll be riding down a hill smacking the light trying to make it work, almost wiped out this evening. :fail:

Click to expand...

If you ride trails anything like I do, death or serious injury is possible during the day so stop being a fool and putting your personal safety on the line just because you're too cheap to buy a decent quality light.

Read this troubleshooting guide... in particular item #5.

I'd suspect a loose switch retaining ring. As noted, some are left hand threaded, others are right.

jon_slider said:

Dude! I'm worried about you. Throw that broken $8 light in the trash, before it kills you, and treat yourself to something more durable.

Click to expand...

AussieRanga said:

If you ride trails anything like I do, death or serious injury is possible during the day so stop being a fool and putting your personal safety on the line just because you're too cheap to buy a decent quality light.

Click to expand...

Perhaps valid points to a degree but the light is well made(it was $20 so not totally rubbish) and otherwise awesome, been working well for the last few years, this issue has just cropped up recently, nothing major why throw away a perfectly good light that just needs some maintenance.

Poppy said:

Read this troubleshooting guide... in particular item #5.

I'd suspect a loose switch retaining ring. As noted, some are left hand threaded, others are right.

Click to expand...

Unfortunately not, the retaining ring is tight, I have a special tool for opening those rings, so I can confidently say it is adequately tight.

I have found in several cases with several flashlights an ever-so-slightly loosened tail cap can make a light become.. difficult.
Try making sure the tailcap is completely tightened. If it turns out that is the case you can add a bit of pipe thread tape to ensure it stays tight while you zoom around on your bicycle.

Mountain Bloke said:

Perhaps valid points to a degree but the light is well made(it was $20 so not totally rubbish) and otherwise awesome, been working well for the last few years, this issue has just cropped up recently, nothing major why throw away a perfectly good light that just needs some maintenance.


Unfortunately not, the retaining ring is tight, I have a special tool for opening those rings, so I can confidently say it is adequately tight.

Click to expand...

You say the tailcap retaining ring is tight, but have you taken it apart to check for debris and clean it? A little spec of sand in the wrong place can make a difference....

What's the make and model of this light? Buying a new tailcap or switch might be the easiest way forward if fiddling with the tailcap doesn't resolve the issue.

ronniepudding said:

What's the make and model of this light?

Click to expand...

see post #1:

Mountain Bloke said:

CREE Q2 LED Power 240 Lumens Digital Torch

Click to expand...

click on the underlined words to learn where to buy a backup for $7.73

ronniepudding said:

You say the tailcap retaining ring is tight, but have you taken it apart to check for debris and clean it? A little spec of sand in the wrong place can make a difference....

What's the make and model of this light? Buying a new tailcap or switch might be the easiest way forward if fiddling with the tailcap doesn't resolve the issue.

Click to expand...

I have opened it before, I'm sure I tried spraying the switch with contact cleaner which doesn't seem to have helped, I want to try just replacing the switch, can I just find a similar looking switch and swop them, obviously with a soldering iron etc. I'm just wondering if a straight swop out is possible, if I won't perhaps mess up the High/Low circuitry, I'm not to sure how that works?

jon_slider said:

see post #1:


click on the underlined words to learn where to buy one for $7.73

Click to expand...

You are trying to be a smart *** but ya using your link I found the link below which looks almost identical to the light I have, listed at $48:
http://www.aliexpress.com/item/Digital-Torch-CREE-Q2-2-mode-1x18650-LED-Flashlight/335319744.html

Its a well made light, body machining is good, glass lens/metal reflector, the basics are good, with some mods it could be pretty respectable.

jon_slider isn't just trying to be a smart a$$, I think he's succeeded

I don't know this light, but usually the switch itself isn't anything fancy, just an on-off plastic bit. So it shouldn't require soldering, but you gotta find the right part if you want to replace it, and I sorta doubt the manufacturer of this light will provide that level of communication, much less actually send you the switch. Hey, if you want to try, give it a whirl... The thing is, if your time is at all valuable, it's easier and cheaper in the end to just buy another $8 light.

If you can do basic soldering and desolder the original switch from the PCB, you can find a variety of replacement switches at mountain electronics.

thslw8jg said:

If you can do basic soldering and desolder the original switch from the PCB, you can find a variety of replacement switches at mountain electronics.

Click to expand...

That's what I'd like to do, seems to be a pretty basic soldering job, as far as I can ascertain the switch is faulty and replacing that will get the light back to perfectly working condition.

I don't know why people have to try derail a thread with self righteous bs, it's a cheap light(although how long is a piece of string), but it does the job fine and just needs a little help to get fixed. I'm not asking for advice on a new light rather how to fix the one I have.

From past experience I've also found fixing a cheapie is good practice for when the time comes to fix the more expensive ones. I am planning on retiring this light from bike duty, still looking for the right replacement, even then I want the light fixed, it's a good spare light to have in my toolbox.

Self righteous rant over

Mountain Bloke said:

You are trying to be a smart *** but ya using your link I found the link below which looks almost identical to the light I have, listed at $48:

Click to expand...

$48? no
the top link in the search I posted for you is this:
CREE Q5 Led 240 Lumens bike Bicycle Head Light Torch Mount … for $7.73

and yes, I respect that you still want to fix your light

ronniepudding said:

jon_slider isn't just trying to be a smart a$$, I think he's succeeded

Click to expand...

LOL! nice to be in good company

jon_slider said:

$48? no
the top link in the search I posted for you is this:
CREE Q5 Led 240 Lumens bike Bicycle Head Light Torch Mount … for $7.73

and yes, I respect that you still want to fix your light

LOL! nice to be in good company

Click to expand...

Dude, bro, ease up on the whacky tabacky!
That link goes to a POS light that looks absolutely nothing like the light I have, what the heck are you going on about?

Mountain Bloke said:

I have opened it before, I'm sure I tried spraying the switch with contact cleaner which doesn't seem to have helped, I want to try just replacing the switch, can I just find a similar looking switch and swop them, obviously with a soldering iron etc. I'm just wondering if a straight swop out is possible, if I won't perhaps mess up the High/Low circuitry, I'm not to sure how that works?

Click to expand...

Earlier you stated that you jumpered the neg pole of the battery to the body and the light turns on reliably. You can try turning in on and off quickly that way, just as you do when you want to change modes with the switch. IF it changes modes, then the circuitry is in the head, not the tail cap. THEN, there wouldn't require any soldering at all, but a straight out swap of the switch.

IF it does not change modes, then the driver is likely in the tail cap.

You might also take the light apart and look for a broken soldered joint.

Ok first step I'll try just now is looking at the tail cap switch, swopping it out if necessary/possible.

Is there a chance there may be a dry joint in the head somewhere, is that something that does happen and exhibit the issues I have been having?

Poppy's advice sounds very good.

It seems that there was a misconception earlier re: what light you have, which led to some of the comments that you indicated were off topic. Please keep in mind that we're all trying to help you.

ronniepudding said:

Please keep in mind that we're all trying to help you.

Click to expand...

I respect your helpful style, and apologize to you for my earlier teasing, because the OP did not provide a photo or sufficient info for me to google his light properly.

Thanks Jon, no offense taken earlier on.

So Mountain Bloke, how are you making out? did you figure out if the driver is in the tail or not?

Haven't had a gap yet, suppose its the procrastination disease compounding my situation!

I'll end up opening the light and it'll stay in pieces for weeks but it's driving me nuts as it is though so I need to knuckle down and sort it out. Will definitely report back on what I find.