MTG2 color temp is superb in comparison. Makes XML’s look awful.
Well done :bigsmile:
Digikey, Mouser, Newark, ebay even.
I only built a few of these drivers, I just used what I could scavenge from dead parts. The most commonly used Zener diode is a SMD part (black, rectangular, looks like the original polarity protection diode that gets discarded) and rated 4.3v, 1/4 watt. Most others use a 200 ohm 0805 SMD resistor. The values here aren't super-critical, they just have to 1- fit, and 2- keep the MCU in a safe range (under 6v).
resistor: http://www.digikey.com/product-detail/en/ERJ-6GEYJ201V/P200ACT-ND/90020
diode: http://www.digikey.com/product-detail/en/BZT52C4V3LP-7/BZT52C4V3LPDICT-ND/1629608
You can use anything that matches those basic specs, there is some wiggle room, so if you happen to find a super deal on a quantity of say 220 ohm resistors, grab 'em.
Vinh, here’s what I’ve been using:
Mouser
CRCW0805200RFKEB
1/8watt 200ohms 1%
Mouser
MMSZ5229B
4.3V 0.5W Zener
Thank You guys!
here we go 
The diode recommended in post 41 is too small. it’s only 1/8 of a watt.
http://www.digikey.com/product-detail/en/BZT52C4V3LP-7/BZT52C4V3LPDICT-ND/1629608
I am going to order the .5W instead: MMSZ5229B
250mW = .25W = 1/4 watt. Works fine.
I use the glass axial ones, also rated 1/4W, just because they're what I have.
The I ordered from Digi-Key and they are so tiny there is no way i can solder them. :) I just got the 1/2 watt and it looks good now :)
Ok, I dont seem to be having any luck with this zener mod either.
Can someone tell me if I ordered the correct components?
http://www.digikey.com/product-detail/en/MMSZ5229B-7-F/MMSZ5229B-FDICT-ND/717907
and this resistor.
http://www.digikey.com/product-detail/en/ERJ-6GEYJ201V/P200ACT-ND/90020
I have tried this with the zener in both directions just to make sure. I double checked the LED to make sure its 6V (MTG2). I also tried adding a second resistor in series to make sure that wasnt too high.
All attempts equal same thing= No light. Nothing. Not even a blink.
The components did fit perfectly though LOL!
Those are the right parts and it looks like you've got everything in the correct location. I know this sounds really silly, but did you try the driver before doing the mod? Are you running two cells in series?
Thanks RMM.
I didnt try the driver before I started, but with the zener removed it will power an XML on a single cell. Yes, when I am testing with the MTG2 I did use 2 cells.
This may sound silly but I was actually really hoping I had just done something wrong :(
With the MTG2 and 2 cells, does it make light if you short one of the 7135 OUT pins to ground? What about jumpering the 7135 Vdd pin to the outboard pad on the 200 ohm resistor? Do you have the correct sub-6v present at MCU pin 8?
Thanks for chiming in comfy.
1. With the MTG2 and 2 cells, does it make light if you short one of the 7135 OUT pins to ground?
Yes, this did make the emitter come on brightly.
2.What about jumpering the 7135 Vdd pin to the outboard pad on the 200 ohm resistor?
If by the outboard pad you mean the end of the resistor closest to the rim of the board, No this did not produce light.
3. Do you have the correct sub-6v present at MCU pin 8?
I think you may have found the problem. IF I am measuring this correctly. In order to get a read on this I put the DMM neg lead on VDD and the + lead on the end of pin 8 where the zener is soldered. If that is how to measure it then I only got .79V with 2 cells hooked up, but I have no idea why.
Good, that proves that if we can get the MCU to tell the 7135s what to do, it should work.
It should have... there may not be any voltage present at the output of the resistor (we know it's present at the input side of the resistor, as the red LED+ wire is on the same trace as the upper tab of the resistor).
No, not correct. Voltage between ground and MCU pin 8. In this block diagram the zener connects between the red section and ground, resistor goes in place of the diode (D1).
Check voltage between BAT-/ground and the top pad of the resistor, between BAT-/ground and the bottom pad of the resistor, between BAT-/ground and MCU pin 8.
I suspect a bridge of solder between the lower pad of the resistor and the ground ring, which leaks off all the voltage needed to power the MCU. The resistor value is high enough that the current will be too low to burn anything up, it just won't work. If you find there's voltage at the top pad of the resistor but NOT at the bottom, disconnect the power and check ohms between the battery spring and the ground plane; if it measures the same as your resistor, it's shorted. It gets awfully tight on space in that area and it's easy to overlook.
mouseover for the SRK: (they are aimed at slightly different spots, sorry ’bout that 
)
[/quote]
I wish i have your backyard 
WOOT! Back on track now. Comfychair, I really appreciate your help. I was really ready to throw this whole thing in the trash.
Well, what was it?? :p
Comfychair,
I actually still dont know for sure. Even after all of the testing, removing of the parts, checking for shorts, putting parts back on I still wasn't able to find the problem. I couldnt find a short or any ringer that didnt mirror a stock board.
Finally I decided to try again with a new board and new zener and just like magic I got light.
Even thought I wasnt able to salvage the first driver I dont even care. I am just happy I will be able to deliver product to the customer as promised.
Things would not have turned out that way if you and RMM had not chimed in. After having tried every thing I knew to try my only recourse would have been to use a buck driver instead, or assume I had been shipped mislabeled parts and try ordering again. Sometime a second set of eyes and a little encouragement is is the most effective tool used in this hobby.
Thanks again.
Glad it ended well! I have been similarly frustrated many times.
……I won’t have any stock C8s or C12’s left in a few weeks.
And a special howdy to vestureofblood too!