May be forced to mod P60 Drop-in :(...

Hi,

Awhile ago, I got my first L2 host and this drop-in from Lighthound:

https://www.lighthound.com/Solar-Force-XM-L-U2-Drop-In-3-Mode-27—9-Volts_p_4110.html

I also got an 18650 extension tube with that L2, so I had a 2x18650 light.

Then, I got a couple of these drop-ins from FT recently:

https://www.fasttech.com/p/1179700

and both of these new drop-ins have been working in a couple of L2 hosts for a couple of days.

I don’t know what I was thinking :(, but earlier tonight/this morning, I decided to move the extension tube from the original L2 to one of the newer L2s that had the FT drop-in.

Stupid, I know :(…

When I tried to turn on the light, it flashed for a second and then went dead. As soon as that happened, I realized that I’d really messed up :(!!

So, now, I have a dead drop-in (one of the FT ones), and I guess that I’d like to fix it/mod it, to get it working again.

What would be the best/easiest approach at this point to try to get that drop-in working? What would have mightly blown up? The emitter, or the driver? And, what should I try to replace?

I’ve never done this before, so I’d appreciate any (detailed) advice!

Thanks,
Jim

You probably fried the driver. That’s usually what happens when you run 8.4 volts into a drop-in designed for 4.2 volts.

Just toss the old drop in and buy a new one that’s built for the voltage range that you want. That will be cheaper in terms of man hours than trying to diagnose and repair your old module.

If you want to teardown and rebuild your old module for fun, there’s a step-by-step on Flashlight Wiki. I believe it was written by brted who is a member here.

http://flashlightwiki.com/DIY_P60

Hope that helps.

rojos,

That would be my first inclination, but I was thinking that would be an opportunity to do something that I’ve been dis-inclined to do before. Plus, since I now have the dead drop-in, I have the “body”, etc. that I’d need, like if I was going to build a new drop-in.

Having said that, is there a way to confirm that the LED/emitter itself is not bad, i.e., physically looking at it, so that I can then focus on getting and replacing the driver?

Also, assuming that the emitter is still good, what would be a good/better driver to use for this?

Thanks,
Jim

Most DMM’s have an diode tester setting. It will light up the led faintly if the led is good. I usually just use 2AA’s nimh to test my leds.

I think that the meter I have does that, but how do you tell which is the + and - locations on the emitter? Also, the whole drop-in is still assembled (but not working), i.e., I have started taking it apart yet, so can I get to the +/- contacts that I’d need to test the emitter like that, even if the driver is still connected to the emitter?

Also, looking at the emitter end, there’s a small black insulation cover around the emitter itself. Any ideas how to remove that?

Thanks,
Jim

If you unscrew the reflector from the pill, you will have access to the LED. The wire solder pads should indicate polarity. I have tested leds while still connected to drivers without any issue. But if you want to be sure, you can unsolder or cut one of the wires.

EDIT: Use a pick or something narrow and sharp to pry up the black cover thing.

Think of it as an opportunity to upgrade the driver. I’d recommend this one for a single li-ion and XM-L in a P60: http://www.fasttech.com/products/0/10001683/1122303-7-amc7135-4-group-25-modes-led-flashlight-driver-c

You just need to unsolder the connections to the LED, pull out the old driver from the back, slot the new one in and re-connect both +ve and -ve wires to the appropriate solder pads on the emitter’s PCB. Remember that you can set your choice of modes by connecting any of the stars on the rear of the board to the negative (outer) contact on it.

That was what I meant earlier, i.e., this situation was “forcing” me to try to dig in, even though I’ve hesitated before. Seems like I have nothing to lose, since the drop-in is dead now, so I don’t have to find an empty drop-in.

I just got back in, so I’ll start taking a look.

Thanks for the suggestion, but if I get “adventurous”, I was thinking of trying something more. I’m wondering if the emitter is dead, maybe going for something like a P7? How would that compare to the original XML?

I don’t think the emitter will be dead, overvoltage will almost certainly have fried the driver. If the LED is damaged you should be able to see something wrong with it like a burnt out bond wire…

A P7 would take similar current but be less efficient, so less overall light, and less focused, along with probably a not so nice beam due to being made up of 4 individual dies.

Hi All,

Here’s a picture of the emitter + black insulation disc:

I looked at it with a 40x magnifying glass, and it’s hard to see, but there’re 3 wires coming off the “lower” edge of the emitter. Those seem to be intact. The LED itself is yellowish with lines going across it. Would that have shown some evidence if it was bad, like turning a different color or something?

As I said, the wires seem to be intact, so I think that you all are right, that the emitter itself is ok, so probably the driver is dead.

FYI, I can’t seem to get the black insulation disc off. Is it glued down to the board that the emitter is soldered to or something? I used a pair of (sharp) tweezers, to try to pry it up, both from the outer edge and also from the edge around the emitter (the edge away from the edge where the wires are, but it wouldn’t budge :(…

On the other end, the driver board is soldered to the edge of the pill (?) at two opposing points, so I’m going to have to dig out my old soldering iron (an old Weller station) to try to de-solder that.

Jim

It’s usually a very tight press fit. For best results, desolder and remove the driver, then push out the insulation disk from the bottom.

Prying it out from the top can be pretty difficult. It has to be either pulled straight up from the middle, or removed by pulling up evenly on the sides. If you tilt it even a little, it will jam up against the walls of the pill and won’t come out.

rojos,

It sounds like you’re talking about pulling out the PCB that the emitter is soldered onto? The black disc that I’m referring to (and in the pic) is, I think, just an isolation disc, on top of the emitter PCB, and I was just trying to get the insulation disc out (so far), and not the entire emitter PCB (yet).

The black disc is holding the led pcb down. rojos is correct that it is easier to push it out from below. You seemed hesitant to pull the driver when I suggested a plan of attach. You usually don’t have to desolder the driver to get it out. Just prying it up with a dental type pick (Harbor Freight sells them cheap) will usually get the driver out. Lead is very pliable. I would wait on trying to use the soldering iron. You can do more damage then good if you use too much heat.

EDIT: Once you get this thing apart, you will see how it all fits together and the intimidation factor will drop significantly.

Hi,

I got the black cover off. Just pried it off, it’s a thin piece of black plastic.

Here’s what things look like on the emitter end:

and here’s the driver end:

As you can see from the latter, the driver PCB is soldered to the outer metal thing (the “pill”?) at two points. I really don’t think that it’ll come out unless those two points are desoldered.

This drop-in (an Ultrafire one from FT) may be different than the ones you all usually work with?

Anyway, since I had the black cover off, I did a diode/LED test on it (several times), and it doesn’t look like the emitter will light up, even dimly.

I also confirmed the way that I was doing the diode test, using a spare LED that I had sitting around, and when I do the diode test with that LED, it does light up, albeit very dimly.

But, as I said, when I do the LED test on the LED in the drop-in, I got no light, not even a dim one. NOTE also that when I do the LED test with the meter and the drop-in emitter, I do see the meter reading go lower (open —> shows ‘3.000’).

So, I’m now starting to think that the XML LED may be dead :(??

Jim

P.S. You’re right, I was hesitant :)…

You are right. That driver is soldered in good. I forgot about those brass pills. Those will firmly attach to solder.

The driver may be absorbing the current from the DMM. Desolder one of the wires and try again. If it doesn’t work, try 2s AA’s on the led to be sure.

EDIT: It will be hard to desolder that driver without solder wick or a solder sucker. You can cut the solder with a utility knife. In fact, I would recommend that approach anyway as the heat to get the solder off that pill will have to be quite high. I would cut along the edge of the pill. You can shave off the solder bit by bit if you feel more comfortable with that approach. Resoldering the driver to the pill is way easier than “unsoldering” it.

Please note I added an edit to my last post.

Hi,

Noted :)…

Actually, I have a de-soldering machine/station somewhere.

I haven’t used it in many, many years, so I’ll have to dig it out (or have my wife dig it out) and check if it still works.

If it doesn’t then I’ll try some of your suggestions.

Don’t remove the driver yet.

If the LED isn’t lighting up, the driver might be fine.

Remove the LED and test the driver. If it works, then all you have to do is replace the LED. Replacing just the LED is a lot easier than replacing the driver.

Too late :(…. I was just able to remove the driver - didn’t cut the wires, but got it out of the pill:

I’ve annotated the picture with the chip markings that were visible. I’m assuming that the unmarked chip is the MCU, but that 24C02BN appears to be a EEPROM? Does that mean that this driver is programmable, somehow?

Re. removing the emitter: There’s some “white stuff” that they used to secure the wires to the emitter PCB, and it looks like they put a bunch of that between the emitter PCB and the threads. It that the “Fujik” that I keep hearing about? Is it some kind of glue/adhesive?

If that’s the case, it’s going to be tough to get the emitter PCB out of the pill?

If it has a slightly elastic texture, then it’s probably Fujik. Fujik has relatively low adhesive strength. It’s not easy to remove, but it’s not that hard either.

I would desolder the wires from the emitter first. Then test the LED again to make sure that it is dead. If it is dead, then the good news is that you don’t have to save it and removing it will be a bit easier. If it is dead, you can just use brute force to pry out the pcb. Then scrub off the Fujik residue with a Scotch pad or something similar. If you don’t want to risk damaging the pill, put it in the freezer for like 30 minutes before prying off the LED.