Small Sun ZY-T08 Switch


I bought a Small Sun ZY-T08 a while ago and noticed that it seems flaky. It’ll change modes if you tap on it or look at it wrong, sometimes it’ll shut itself off or just switch brightness. I’ve also had a number of other cheaper flashlights that have a tendency to do the same thing. I assume this is a loose contact somewhere, but have no idea where. Is this a common problem, is there a common place to look?


I would try to tighten the pill better in case its loose.

You could also unscrew the 4 screws on the back and check the the soldering to the button is good.

The contact board is flat. Are you using button top batteries in order to get a good connection with the batteries?

By tighten the pill you mean unscrew the back end (like how you’d remove the batteries) and then stick some implement (small screwdriver) into the the small holes near the outside of the back of the circuit board and try to turn it clockwise? I think I’m using “button top” cells, but I thought all batteries in this form factor are button top.

The driver is pushed into the pill. You can turn it clockwise to make sure it’s tight. But what it sounds like is that your batteries are not making good contact with the driver board. If you are using unprotected batteries they might be too short. You can take it apart and stretch the springs, while you are at it you can make the contact better by soldering a piece of copper wick from the board to the top of the spring. This will effectively bypass the springs. You don’t have to do this second step. You could also solder a drop of solder onto the top of the batteries if they are unprotected. But I don’t recommend this unless you really know what you are doing with a solder gun. Don’t let it heat the battery up. A very quick solder drop and then take a cool rag and apply it just to the top.

Oh and if you have a set of Hemo’s you can always just reach down and stretch the spring that way. But be warned it’s possible to pull too hard and pull the spring out from it’s solder, then you have to take it apart and solder it back together.

I have a bunch of these and have never had a problem with the switch itself.

The similar problems I've had with T08's is when the batteries don't have a well protruding + button (i.e. button top). If they are flat tops, sometimes they are good, sometimes not so good and produce the flakiness you are seeing. This is just one more possible cause, I'm afraid... I've added solder blob's to the + side of batteries just for use in this light.

There are some other members that have had trouble with the switch on the ZY-T08. When I unscrewed the back end of mine to make a mod on the switch, I found the solder had broken away from one side of the switch, and was only held in place by by pressure from the boot cap.

I’ll take it a part and post pics when I get a chance… Thanks for all the responses.

Here’s the battery:

Back of the pill:

Rear assembly:

Well the batteries shouldn’t be your problem so maybe it is the switch.

Remove the screws to access the switch.

Well, I disassembled everything in the back. One of the two screws that holds the switch itself in was loose. Unfortunately, it would appear the female threads (the ones on the flashlight itself) are screwed up (no pun intended). No matter how much I turned the screw it wouldn’t tighten, and it was hard to get out, and I tried both screws.

I’ll try to chase it with a tap, but I’m wondering if I might have to drill it out oversize and re-tap them. Dumb question, anyone know what screws these are? I’m thinking M3x.5?


I took it apart, and retapped the holes that hold the board in for 6-32 screws, cut some screws to length and then put them in with purple Loctite. The board is now being held quite securely, but the problem still exists — it may be better but its not solved. Any other suggestions? I’m not sure how you’d even check anything because to make it fail, I have to shake it. Hard to measure stuff while shaking vigorously. I guess I could try pulling the board out and putting a power supply and pull up resistor on it and then watching on a scope as I shake it.

If shaking it makes it change modes and flicker perhaps the cells are losing contact. Try adding magnets or something conductive to make sure they are snug. If that’s not it, there must be something loose in the head. A wire that’s not soldered well.
Keep up the diagnostics. Flashlights are simple, there’s nothing that can’t be fixed.

Maybe this is a bit late but in case someone finds this thread with the same issue:
I just right now modded my t08 and the switch board only makes contact to the body, through the screws. Using loctite might not be good for a perfect electric path.
I grinded away the anodisation on the flashlight to ensure perfect contact…

I also have recognized the battery issue unprotected bare cells won’t make good contact to the driver. Unprotected cells with buttontop or solder blob work perfect.

Hmm, at least not to me. I have encountered some flickering issues with some of my mods and I still cannot successfully diagnose them. Sometimes I just hope some of the great modders in this forum can be by my side and help me out on these stubborn flickering.