Quick question about light with no on/off switch

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chepar

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Ok, quick (and maybe silly) question:

I picked up a Princeton Tec 40 as a small light to keep in my BC pocket. Primary reasons were the size (very small) and weight (4 AAs). I do not normally use a light when I dive.

When it came in, I realized it had no on/off switch! I guess it just didn't occur to me that it wouldn't have one. It's the type that turns on when you screw down the lens/bulb tightly, and stays on until you unscrew it.

My question: the light stays off while screwing down the cap most of the way, and once it turns on, you have to keep turning about 1 full turn around until it's totally closed. Is it possible to dive with the light off (not completely closed, maybe about 95% closed) without it flooding - and if I need the light, to turn it the remaining amount?

Essentially, there's no point in me having a light that has to stay on the entire dive - if that was the case I will return it and get another one with an on/off switch, but I really liked this one because of the size and weight - all the other ones were quite a bit larger.
 
The Halcyon Scout uses a similar mechanism, and stays turned off during the dive until needed.

Just don't unscrew them too far.
 
...partially unscrewed. It will not flood. I have two CE lights (similar to Halcyon's scouts - also screw type on/off) that are the same way and I have not flooded them yet. I just put in the batteries before the dive, turn the lighthead until the light goes off, and then another 1/4 to 1/2 turn so it doesn't compress on at depth.

No problems yet...
 
To shed a little more light on the subject, the light is sealed by one or more O rings between the housing and the endcap. There is no need to crank the endcap down anymore than is necessary to get the light to come on. To turn it off, just back off from "on" until it turns off and then maybe another 1/2 turn. I have a couple of similar lights and they do tend to turn themselves on when pressure increases so keep an eye on them when taking them UW. Also, if you fly with them, either remove the batteries or put a small piece of plastic between the batteries to prevent them from coming on in your luggage. Anytime you take the light apart, to replace batteries for example, be sure that the O ring and endcap are clean and put a little silicone grease on the O ring to lubricate it before you put it back together.
 
Unscrew the device until the light goes off and then continue to unscrew it until it stays off when you compress the device as water pressure will do. It should not flood.

If you do not unscrew it the additional amount, water pressure will turn the light on. If it is in a pocket, it may be hard to notice.
 
We use a light on almost every dive. Below 90 feet, the light is almost non-exsistent and a light is mandatory. I use a Pelican 3 C Cell as my backup, and it is also the screw down type. Three things to remember.

1) Always keep the o-ring lubricated with a good quality silicone grease. If you let it dry out, the light will flood, no matter how hard you tighten the sucker.

2) Unscrew the light till it turns off, then one half to one full turn more, is the general rule of thumb

3) With no switch to break, this light will last forever. Just remember to check the light before every dive. Keep extra batteries on hand, and change them when needed.

Simple design and reliable. Not as bright as an HID, but then again it's only meant for backup, to get you up safely.
 
I have two Tec 40s. The first one caused me a lot of grief. I thought I was flooding it by unscrewing the head too far, but eventually I realised it was flooding every dive, no matter what I did. Princeton Tec replaced it and the replacement has been fine. I also have a second one that I bought before I discovered that they were willing to replace the first one.

Anyway, tips:

1) When you want to turn it on, just screw the top down until it turns on. Don't overtighten it.

2) As several people have said, it will turn on in your pocket at depth if you don't back it off sufficiently. Of course, if you back it off too far, it will flood. Pays to check what it's up to when you get to the bottom, at least until you get used to its foibles.

3) Some makes of batteries don't make a proper contact in the bottom and can't be used. If you change the batteries and can't get it to turn on, it could be the bottom contact.

4) Check for flooding every time you use it.

5) If you have any problems, talk to your dealer. Princeton Tec replaced my original torch, no questions asked.

To be honest, if I were in a position to start over, I'd get a small torch with a switch -- I don't just don't have that much confidence in my Tec 40s. But maybe I'll warm up to them when I've had a few more problem-free dives.

Zept
 
Zept once bubbled...

To be honest, if I were in a position to start over, I'd get a small torch with a switch -- I don't just don't have that much confidence in my Tec 40s. But maybe I'll warm up to them when I've had a few more problem-free dives.

Zept

I would probably prefer a light with a switch also, but I purchased mine online from Divers Direct, and didn't notice it didn't have a switch. All the lights I saw at the various shops here were larger than I wanted. Hopefully I won't have any problems with mine.

Thanks for all the advice!
 
...but the switch on a backup light(s) is just another unneeded failure point. Think about it, the mechanism for turning on the light on a switchless light is just tightening the lighthead a little and thereby completing the circuit. All sorts of little springs and moving parts have to work correctly in a switched light in order for the circuit to complete.

I have a switch on my canister light, but I am glad that I don't have one on my backup lights....why do you think I carry an extra switch for my canister in my dive bag?
 
https://www.shearwater.com/products/teric/

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