SOLVED - Replaced emitter/emitter PCB, light now single mode?

Flashlight Modding and DIY Parts
1

Hi,

I ended up with a junk C8 from a recent deal. I don’t remember what kind of emitter it came with, but I decided to replace just the emitter with this:

https://www.fasttech.com/p/1287502

So, I went ahead and did that tonight.

However, after I removed the original emitter PCB, the leads were really short… just above the holes on the emitter side of the pill.

I didn’t want to replace the driver (too much trouble for this light), so I went ahead and soldered the emitter PCB +/- to the existing leads from the driver.

Then, I put the light back together, and was pleased that it was really bright, but I noticed that it didn’t have any modes anymore (remember, I didn’t do anything with the driver)!!

So, I took the light apart again (sigh :(!), and was looking at it under a magnifying glass.

That emitter PCB I linked above is aluminum, I think, and I think what’s happening is that the negative lead was stripped kind of far back, and because of that, when I soldered it, it’s touching a bare part of the emitter PCB. The emitter PCB is sitting on the pill, which is connected to the head, which is connected to the tube, which is the negative for the battery, so that’s why it’s now in single mode/direct drive.

Ok, I think I got that :)…

The question that I have is, given this situation, where I don’t have any chance to lengthen the driver-to-emitter PCB lead, and re-strip the end so it won’t have contact with the emitter PCB, is there any way to prevent that contact (and to get the driver and its modes to work)??

If you look at that emitter/emitter PCB I linked, the + and - pads are really close to the “notches” and the sides of the notches are coated with anything, so is there any way to prevent the exposed part of the lead from touching?

Thanks,
Jim

2

Check ohms from the LED- pad to pill body. If it shows a short, desolder the wire from the LED- pad and check from the wire to the pill, and from the LED- pad to the pill.

EDIT: Also, did you confirm it has the same symptom with the new reflector removed?

3

FYI, it wasn’t a new reflector… it was the original reflector. The only thing that I replaced was the emitter/emitter PCB. Also, there’s a plastic disc covering the entire front of the pill (except the opening for the emitter :laughing:.

I’ll check what you suggested, but the back of that emitter PCB is just bare aluminum, i.e., not coating or anything, so I’m pretty sure that there’s conductivity from all of the bare parts of the emitter PCB (e.g., the LED- pad) to the rest of the pill (and to the body, and the battery negative).

Will post back…

Jim

4

It probably is the - wire shorting to the MCPCB.
You can simply replace the wire from the driver to the emitter with ne that has the coating still on it. Just strip it enough to solder, leaving the edge protected.

5

I know that this is going to sound dumb to most of you, but until tonight, I’ve always assumed that the emitter PCB was insulated from the rest of the light :(…

6

With the copper Sinkpads, I most times solder them into the pill instead of crappy white silicone bathroom caulk (sometimes called 'Fujik') or epoxy. Solder is easier to remove at a later date - just add heat!

So it would be a Bad Thing if the MCPCB base had continuity to the LED- pad (similarly, if it were built with the - pad as part of the base, why wouldn't the + pad be the same way?)

If you have a spare MCPCB you don't mind destroying, gradually shave it down layer by layer with a hand file. Do a dissection and see what's really in there.

7

- pad to pill short

Remove - wire

- pad to pill open

  • wire to pill open

I found that from the edges of the PCB to the pill it was shorting (the edges of the PCB don’t have any coating), so I think that the - wire was contacting the inside edge of the notch.

After I unsoldered the - wire, I pulled it out as far as I could (not much, and I didn’t want to break the wire), and then carefully held the bare part to the solder pad and heated that up. Held it for a few seconds, and then ohmed from the - pad to the pill, and got an open.

Tested the light, and I now have mode again :)…

That was the good news.

The bad news is that tailcap current was > 3 amps, and is now 1.28 amps… another proof that the driver is in play ( :slight_smile: )…

So, lesson learned here… The bare parts of the leads to the emitter PCB pads shouldn’t be shorting to anything, other than to the pads.

8

I figured that was the problem. Good stuff.
Looks like you need to “enhance” that driver. Take a pic, we’ll see what can be done :wink:
Edit: Is that the $5.99 C8 from eBay with a generic emitter?

9

No, it’s a “Honree HC8”.

A bit convoluted, but I got it when I ordered a Trustfire TF-R2 (instead of the TF-R2).

The seller tried to convince me that it was a “new version” of the TF-R2.

RIGHT :)!

I was able to start a dispute at Paypal, and then we ended up settling with the seller refunding most of the price I had paid them for the TF-R2 (which I never got from them), with me keeping the “HC8”, rather than shipping it back to them.

10

OK, just checking. I had that, and the driver basically sucks but is salvageable to at least 2.5A or so.
If you want to attack the driver, post a pic if it is more than a bare PCB :smiley: