SSC Failure...

[richardb]

I am still investigating,
but I had a SSC plugged into a passive HUB and a 12V regulated, current limiting power supply, I had a 128 light string hooked up and when it hit White with the Test Firmware, it locked up.  I smelled an "electronic" smell, and noticed the power supply had current limited at 4 Amps.
Upon resetting the power supply, operations continued as normal...  The first time it ran for 5+ minutes, the second time, I got to white the second time as it looped through the test sequence...
I reset it again so I could check items and heard a POP followed by a second POP and then nothing...
Autopsy indicates the 3.3V regulator is shorted, producing 12V at pin 2 (Output).  The PIC was HOT to the touch, I assume dead... since it was getting 12V crammed down its throat.  Haven't tested it in another board yet...
I've looked for the obvious...  and found nothing...
I have not applied the "Resistor" fix, as I am still running the 330 Ohm resister (The 150's have not come in yet...)  This is my first suspicion.... But if this was the cause, I've read no one else reporting the release of magic smoke due to it...

Anyone else had something similar to this?

Richard

[rrowan]

I would assume a soldering issue.

Magnifying glass to find the short and then replace the parts that "pop"

Sorry

Rick R.

[richardb]

Nope, I don't suspect that's the case (I've checked for obvious shorts, and Ohm'ed for shorts under the DIP sockets).  And it was fully functional for 5+ minutes...  So, unless the short was on a current limited resistor or similar, the short would have caused immediate failure...
I suspect it has to do with something else...

[RJ]

Something to think about, The Regulators are themally protected so you can have a mild short and it can run. The reg cycles fairly fast. But if run this way it can cause it to totally fail after a while. So I do not have a way to know this is the case but it is a possibilty. also the reg could have been bad and just failed. The resistor change would not have an effect on this. The 3.3 reg only drives the pic so a dead short on the lights would not even do this. It would damage other things. The 3.3v reg is only outputing a few milliamps so it is not run hard at all. 

Let us know what you find.

RJ

[richardb]

Thanks for the quick feedback...
I will investigate this shortly...
It ALWAYS failed with ALL WHITE lights on...  Which is when the current draw would be highest...
But, I will investigate after replacing the 3.3 V reg... and then monitor the current draw of the pic...

Again, thanks for the quick response!

[RJ]

It ALWAYS failed with ALL WHITE lights on...  Which is when the current draw would be highest...

Thats the thing. The current draw is greatest at full white for the lights yes. But this bypasses the regulators totally. They really do not know how much the lights are drawing. The power comes in the pigtail and goes straight to the output to power the lights. 

The current from the 3.3v regulator will not change very much. The difference would be within maybe 20ma no matter what.

RJ