MTN Electronics: LEDs - Batteries - Lights - Chargers - Hosts - Drivers - Components - 1-Stop-US Source

I have got a problem with a 26mm FET+7135 MTN driver. I soldered it myself, with a soldering iron first, then again repassed with hot air. I use it in a zoom flashlight with XHP70.2 and Crescendo. However it makes the led flicker when on. It is not that obvious but there are constantly some variations in brightness, though slower than any PWM. If there are some driver experts around here, could you please help me spotting the problem?

Maybe some intermittent poor connection or partial intermittent ground out. I'd check the usual culprits first - LED wire grounding out with the reflector - so try running it with no reflector and see if it goes away. Another area is grnd connection to the driver - good contact at the tail end of the tube, and upper end of the battery tube - can remove the tailcap use a heavy wire to test. After that, look for driver component contact with the grnd ring - sometimes mounting these drivers in lights not designed for it has clearance issues - can test by removing the driver and air testing.

You may have done all this or the equivalent and didn't mention -- please detail everything you tried already.

Yes, I tried quite many things already. Here is a list:

- bypassed the tailcap with a wire

- used different batteries

- tried only the pill with wires connected

- only the XHP70 running direct drive, NO flickering

- put soldering paste on all components, soldering everything again with hot air

- tried a 10uF condensator on C1, result only constant Turbo, removed again

- changed the Zener diode for another, bigger one

- removed the FET and soldered it again

  • changed the OTC condensator for a different one with same value
    At this point my knowledge about drivers ends. I can not determine if there is a faulty component on the driver or if something else is wrong. I used all the components from MTN electronics. At the same time I soldered another 26mm driver with Bistro and that one works well.

This might be too basic, but I would still like to mention it:
My S2+ flickers in a very similar way when the threads are dirty (either head or tail or both). They may even look clean, but I have to clean them with rubbing alcohol and then the drivers works again.

Hhmm, could be a faulty driver board or part - may get some cross coupling of signals with some intermittent contact or proximity interference - unfortunately still a few possibilities remaining...

Probably did this already, but go over the board carefully with a strong magnifier (microscope preferred) and check for nasty solder splashes or contaminants, or anything that looks too close for comfort. I always give drivers I build a close inspection and bath in fair amt of isopropyl alcohol to get rid of contanimants as much as I can. For me at my age, I need magnification and light on the object - equally important.

For the threads issue, interesting because the threads on the tail, for example, are anodized and don't conduct electricity - you have to look at where the electrical paths are, and yes, they can get dirty or have oxidation issues.

Thanks for your advice, Tom E and USA! :laughing: So you would say that there is basically not a driver component responsible for flickering, right? I will try to clean the threads on the tail and the pill of the flashlight. If cleaning the driver does not resolve the issue I will try to swap another driver in the flashlight.

If you give it a cleaning, use a stiff brush with the isop. alcohol - I'm using a brush that came with a razor, maybe a toothbrush would do as well, or something similar - 90% isop. is good to use, nothing lower, available at most drug stores.

Ok, I’ll try it. Thank you for the tip! :+1:

You could also use a small cotton wool lightly dabbed in hydrochloric acid(or muriatic acid alternatively).

That will surely get rid of any oxidation or debris.

I’ve found flickering issues are very commonly associated with ground problems. The retaining ring on the switch pcb, or even the bare metal under the switch pcb, quite commonly causes these kinds of issues. Most likely there is a place in the multiple contacts that has dirt on it, visible or otherwise.

Richard has been using a thinner PCB for his drivers, make sure the driver is actually getting a solid contact on the retaining ring. If not, build it up some with solder blobs in a few places around the ground ring then double check the retaining ring. :wink:

That’s been pretty much my experiences too.
This problem seems to magnify drastically when you start pulling 10 amps or more, which Dale does quite frequently. :wink:
When asking for lots of power, connections, wire size and length, spring resistance and battery sag mean everything.

BlueSwordM has a group buy going on here that, in addition to his springs, includes SST-20:

He’s ordered some, and I lost track of what he is still planning to order, but you can always ask.

The other option is Kaidomain currently offers the SST-20 in multiple color temperatures and decent output bins.

I’m expecting Richard himself to be coming in here soon with some really good news. :smiley:

Ohhhhh Riiiiichard……?

Wherefore Art Thou, Counselor?

LOL

I still have 3000k SST-20s left as iamlucky noted.

Any hints? LED's, batteries, drivers, lights?

Yeah, give us some hints :slight_smile:

The suspense is killing me… :disappointed: