Apologies....I was unclear, the firecracker wasn't in the LNMP, mercifully. It was in one of the units the LNMP was built to examine.
I have a test procedure to help catch things like polarity errors. Care to poke holes in it for me?
Since I usually build multiples;
Step 1: Line 'em all up with the same orientation and inspect, checking for:
joint solder is shiny and flowed through nicely on both sides of the board
resistors should be oriented uniformly, markings readable, ratings identical.
diodes- all stripes on the same ends
Caps grouped by type, cans first, tants second, etc. Polarity and/or markings should all face the same way.
ICs- double check markings and orientation.
Test points all present
LED flat spots on the bases all oriented the same way
Step 2: check for consistent component altitude above the board. I used to crank them down tightly with pliers. Bad idea. I wasn't thinking about heat, expansion or other stresses. I got good desoldering practice after that.
Step 3: connectors and sockets look clean, good, right number of positions, etc.
Some other things- I run my fingers over the bottom of the board to find any irregularities - this helps me find iffy solder work, uncleaned flux, anything that stands out.
I look for anything crooked, leaning, or bent...
Unless I surpass myself and, for example, put ALL the diodes in backwards, this screen saves a lot of unpleasantness later.
Here's what remained on the board of my firecracker (pic)
Looks right to me... do you think it was a faulty part?Edited by saraengelstad - 3/29/15 at 2:21pm