Continuity Issue wih SSC P4

[supasizefries]

I am trying to mod a light of mine with a U-bin P4. Before even putting the LED in the light, I quickly wanted to power it up just for a second or two via direct drive to a AW RCR123 protected battery. With the - wire clipped to the - leads on the LED, the problem I'm having is that I can only get the LED to light up when I touch the + wire to the slug on the bottom of the emitter. When I try to use the actual + leads on the side, it will not light up. I've read about these having the anode connected to the slug but it seems the + leads on the side do not work. Am I doing something wrong?

 

[Black Rose]

The + leads on the U and U2 bin SSC P4s I have installed to date worked fine.

 

[Justin Case]

You are contacting the longer "dogleg" LED+, not the shorter stub? Also, sometimes contact resistance is high and the LED doesn't light up. Make sure everything is clean and try to make maximum areal contact between your wire and the LED+.

You can avoid these issues by temporarily soldering wire leads to LED+ and LED-. I'd attach the LED to a temporary heat sink (any decently large chunk of metal) using some thermal compound first, so as to reduce the likelihood of possible heating up of the LED from the soldering operation. You can easily de-solder the wire leads afterward, remove the LED from the heat sink, and clean up the thermal compound.

Then clip your power source to the wire leads to test for go/no-go function.

 

[supasizefries]

Hi JC, yes I was contacting the longer leg on LED +. I actually ended up soldering wires to both legs for LED +/- because I was getting tired of trying to touch the tiny legs with the wires. Unfortunately I didn't think of the temporary heat sink solution you recommended. I'll remember that for next time. Thanks for the tip. :thumbsup:With the wires soldered I still could not get the LED to light up...only when touching the slug. I was testing for continuity with my Radioshack DMM and could only get tone when contacting the slug on the back. I'm starting to think that the LED + legs are shot.

The p4 was only $4 and change from DX so I guess it's not too bad of a loss.

 

[ROK]

You have to handle the SSC P4 carefully.

Any pressure on the soft dome of p4 can make a problem of bond wire broken.
Guess your problem is this case.

 

[Tekno_Cowboy]

Just to be sure, you are using the side with the solid short tab as the positive side?

 

[supasizefries]

Just to be sure, you are using the side with the solid short tab as the positive side?

Yes that's correct. And, I'm connecting the - to the side with the little half-moon notch in it.

I bought 2 of these from DX. One p4 is currently in another light I modded that works fine.

 

[wildstar87]

If you want to try to save it, I have actually soldered a small piece of metal, that I pounded out real thin onto the slug, then bent it up to where the positive lead would be. This has happened when I accidentally pulled the positive lead off.

Then after I epoxied onto the heatsink, just soldered like normal, worked just fine.

 

[supasizefries]

If you want to try to save it, I have actually soldered a small piece of metal, that I pounded out real thin onto the slug, then bent it up to where the positive lead would be. This has happened when I accidentally pulled the positive lead off.

Then after I epoxied onto the heatsink, just soldered like normal, worked just fine.

Hey that sounds like a pretty good solution. It's worth a shot! Thanks for the tip. :twothumbs