Changing TR-801 driver?

[Oznog]

I have a TR-801 with all the modes and I read better things about DX's sku.15880 driver. In particular, the TR-801 doesn't "boost" well (or at all) and dims a lot as the batt goes down, the 3 intensity modes aren't remarkably different intensities AND the PWM is way too slow, it's totally visible to me and too irritating to EVER use. The sku.15880 is supposed to fix all that. So I got one.

Well, I opened the TR-801. The driver is held in with a brass ring which it's soldered to, but that ring doesn't seem to be soldered into the pill, but desoldering it while it's pressed against the pill may be futile. I tried to pop the brass ring and driver out with a screwdriver but no luck. How does it come out??

 

[kramer5150]

Hmm... can you post a pic of the pill? I want to see where the DC-DC board is soldered to that brass ring, before instructing you further.

 

[Oznog]

Just 2 solder points 180 deg apart. Yeah, I could probably melt those off easy, I just figured removing the brass ring would be the first step.

I looked up someone else's disassembly- no good pics of the pill, but the driver is a crummy linear reg. No boost ability at all, and inefficient when Vbatt>Vled. Well, it's a great case and Q5-WC, something had to give to bring the cost down like that. Wish I'd gotten the cheaper 1-mode over the 5-mode since I've gotta swap the driver anyways.

I noticed the Q5 is on an MCPCB, but the MCPCB is only glued to the pill with this white silicone stuff. Probably not the best for thermal conductivity, but it's a decent contact area. It is safe to try to pry it up and scrape it so I can put in some Arctic Silver epoxy, or does that sound too risky?

 

[Jarzaa]

I changed the driver on my TR-801 to one of the DX 1050mA multi-mode 7135 drivers. The original driver on at least on my TR-801 was totally unregulated PWM driver. There is just a transistor that is switched on and off by a microcontroller. You should unsolder the two points where it is attached to the brass ring. The ring is press-fit in the pill and may indeed be tight. I didn't think it was difficult at all to get the driver off. Here are pictures of the original driver and pill I had.


I think the newer ones may have different driver than what was used when i got mine about 8 months ago. The driver you mentioned should have constant output but I would not be surprised if it was much more inefficient than a linear regulator.

The LED can be relatively easily pried of the pill. The thermal glue that many of the DX products use is a bit flexible and does not adhere that tight, unlike the arctic silver thermal epoxy. You should be able to pop it off with a screwdriver. That is how I did it when changing mine to a Q3 bin 5A neutral white tint LED.

 

[Oznog]

When replacing the driver, did you unsolder the wires from the LED, or did you unsolder the +/- LED output wires from the driver? I can certainly take off the wires at the LED, but it's difficult since the board effectively sinks away soldering heat and the angle you can bring in the iron tip is limited. If the wires are too short to pull out the board though then it's unavoidable anyways.

 

[LukeA]

I soldered a short piece of copper tubing to the positive contact for better pulling after filing the solder bridges off. I desoldered the wires from the LED rather than from the board. It's just a lot easier.

 

[Oznog]

Well I just finished the job, all the expected problems showed up:
1. I desoldered the wires off the LED, which turned out to be completely unnecessary! There's enough slack to drop the driver. In fact, desoldering made a mess of the wires, melting the insulation, and were hard to get back on.
2. Man getting the old driver desoldered was tough. I SHOULD have ground off the solder, maybe. Or at least used a blunter soldering iron point. This got the whole piece REALLY hot, and the solder sucker didn't work right because it was BARELY melting.
3. The fit's really tight, and the solder can't readily be cleaned off the inside of the brass ring. I ended up Dremel-ing out the old solder first, used some sandpaper to smooth the area where the tabs used to be, and it fit, but really really tight. I bit down lightly to pressfit it in.

Soldering it back in was not as hard. Kinda the same problem of getting it hot enough to melt, but applying solder was so much less complicated than cleaning it off, it went ok.

This driver is proving to be problematic, it doesn't always hold the mode and I keep getting the stupid "Strobe" every once in awhile.

 

[kosPap]

now let me understand..which driver was the problematic one? the Dx 15880?

did you try installing this? is there enough room in the pill for it?

 

[Oznog]

Yeah, the 15880. It's tight but it fits.
As a buck/boost converter, it should be a good performer, but with mine the mode-changing problem is just a mess.

I didn't like the original linear driver the TR-801 comes with, like all linear drivers it dims a lot once the battery is anything less than 2/3rds full charge or so. Plus its other two light levels are PWMed at far too low of a frequency, it's so noticeable on moving objects I can't use those modes at all. It's disorienting.