Gryloc
Enlightened
So I have (well had) a nice U-bin Seoul Semiconductor P4 in a Streamlight ProPoly 4AA flashlight and it was my favorite and most brightest flashlights I owned. Nice combo of a bright LED and deep reflector. I loved it to death (well, quite literally). I removed the reflector from it again to test other types of reflectors. I wanted to see how the Mini-Mag-light LED reflector would do wtih the P4, as well as a spare trimmed IMS SO20XA. When I was done playing, I placed the special plastic centering ring back around the LED and carefully pushed the whole LED emitter (attached to a star) by it's sides down to make sure it had good contact with the heatsink. I put the original PP reflector back on then turned it on to make sure it was focused. Nothing happened. 
Oh crap!
Well, I pulled it back apart (rather easy the way I have it set up) and made sure the soldered connections were alright. They were. Then I tried to apply power straight to it, in case a wire within the module broke. I have the light in DD mode with a dummy battery in there until I get the driver circuit fixed (I really need to do that). No wire was broken and the P4 emitter still didnt light when directly powered. Doh!
So, I was looking at the emitter, confused and frustrated, then I had an idea. The soft gummy dome could have been pressed in, damaging the bond wires. I looked closer and touched the dome a bit, and sure enough, the bond wires were sheared off at the edge! Argh!!! I could see them move as the dome flexed. Why me?! This is at part a flaw of the P4 design. The bond wires for the negative contact to the LED die (2 total) and the bond wire to the ESD diode all connect to that negative metal contact way over there on the edge/rim of the dome -ready to be broken. I could have pressed hard elsewhere and the P4 would have survived. There is a small positive bond wire (or two) hidden well on the opposite side that connects the slug to the positive lead. That one can be broken easily, too (but use the slug as a backup contact in this situation).
Well, I tried finding ways to light it up, since the die was not destroyed, and I couldn't get probes to work. Newbie mutilated a P4 back in the day, to find the die pooping loose and sticking to the dome (a different problem -bad joint to the slug). Mine stayed put, and I was careful to save as much of the bond wires as possible. With the dome off, I could see that a tiny bit of bond wire stuck up from the top of the P4 die (its negative). So, I touched a positive power wire to the slug (which does work a safe backup positive contact, by the way, as Newbie found), then I touched the negative to that tiny bond wire sticking up.
Sure enough, I was temporarily blinded.
So, the LED still works, but only when you power it up in a PITB way.
Today's lesson kids: Do not press on the dome of the Seoul Semiconductor P4 LED emitter. You will regret it!!!
I knew the Cree XR-Es dome was sensitive since it can pop off, and I got used to the old hard dome of the old Luxeons, and I did not pay enough attention when I handled my prized emitter. I say jeers to myself for being so careless (kidding). Only bad things happen when I play with my LED's past 2 in the morning! I will learn... someday. I am always careful, but I pressed just right, apparently.
So, if you P4, or even your K2 stops working for some odd reason after you handled it a bit, then you know why now!
Please leave comments or questions, or even stories about similar mistakes (people make them -I hope it was not just me). For those that haven't experienced this yet, I hope my mistake was useful to you. Maybe you can look at yout P4 in a different way (as a frail monster). So, I guess this is a warning for the careless or clumsy!
Alright, good luck, be careful all, and take care of your LEDs!
-Tony
Oh crap!Well, I pulled it back apart (rather easy the way I have it set up) and made sure the soldered connections were alright. They were. Then I tried to apply power straight to it, in case a wire within the module broke. I have the light in DD mode with a dummy battery in there until I get the driver circuit fixed (I really need to do that). No wire was broken and the P4 emitter still didnt light when directly powered. Doh!
So, I was looking at the emitter, confused and frustrated, then I had an idea. The soft gummy dome could have been pressed in, damaging the bond wires. I looked closer and touched the dome a bit, and sure enough, the bond wires were sheared off at the edge! Argh!!! I could see them move as the dome flexed. Why me?! This is at part a flaw of the P4 design. The bond wires for the negative contact to the LED die (2 total) and the bond wire to the ESD diode all connect to that negative metal contact way over there on the edge/rim of the dome -ready to be broken. I could have pressed hard elsewhere and the P4 would have survived. There is a small positive bond wire (or two) hidden well on the opposite side that connects the slug to the positive lead. That one can be broken easily, too (but use the slug as a backup contact in this situation).
Well, I tried finding ways to light it up, since the die was not destroyed, and I couldn't get probes to work. Newbie mutilated a P4 back in the day, to find the die pooping loose and sticking to the dome (a different problem -bad joint to the slug). Mine stayed put, and I was careful to save as much of the bond wires as possible. With the dome off, I could see that a tiny bit of bond wire stuck up from the top of the P4 die (its negative). So, I touched a positive power wire to the slug (which does work a safe backup positive contact, by the way, as Newbie found), then I touched the negative to that tiny bond wire sticking up.
Sure enough, I was temporarily blinded.
So, the LED still works, but only when you power it up in a PITB way.Today's lesson kids: Do not press on the dome of the Seoul Semiconductor P4 LED emitter. You will regret it!!!
I knew the Cree XR-Es dome was sensitive since it can pop off, and I got used to the old hard dome of the old Luxeons, and I did not pay enough attention when I handled my prized emitter. I say jeers to myself for being so careless (kidding). Only bad things happen when I play with my LED's past 2 in the morning! I will learn... someday. I am always careful, but I pressed just right, apparently.
So, if you P4, or even your K2 stops working for some odd reason after you handled it a bit, then you know why now!
Please leave comments or questions, or even stories about similar mistakes (people make them -I hope it was not just me). For those that haven't experienced this yet, I hope my mistake was useful to you. Maybe you can look at yout P4 in a different way (as a frail monster). So, I guess this is a warning for the careless or clumsy!
Alright, good luck, be careful all, and take care of your LEDs!-Tony
