PSA: Situational Awareness!!!Good afternoon, fellow eevBloggers... today I'd like to take a moment to talk with you about Situational Awareness.Above we can see a first-person view all of you should be pretty familiar with. I was having a little "quiet time" troubleshooting an old linear power supply. Had my datasheets printed out, several reference schematics all around me... I was just pleased as a mouse in a barn with an open grainery. Well, after a while I'm pretty convinced the LM723 has given up the ghost again; this thing had poor OCP on its best day, as the series-pass driver can spike 5A base current up the chain. I'm sure it hasn't gotten any better in the last 30 years with dried-out caps and the death of the 2N3055s it was designed with. But hey... I have one in a junk PCB I can scavenge, so it's all good, right?
Anyways... all this while, I had been experiencing a gradual warming in my nether regions... like the proverbial frog in a slowly warmed pot of water, I didn't notice anything until it was much too late; in fact I probably would've found the sensation pleasant at first, had I actually taken note.
But hey; who among us hasn't gotten a little tingly when puttering away at the bench, especially at that
Eureka! moment, right?
So right about this time (no doubt since my attention had returned to the real world, as opposed to the theoretical world of ohms, bias voltages and current shunts), I notice a strong smell of "fresh-pressed cotton", and a right proper burning sensation in my junk region.
I drop my probes, push myself away from the bench, and find this dangling right at groin-level!
It's a quick & dirty light-bulb load array I'd left on the unregulated outputs the night before during preliminary troubleshooting before I pulled the control PCB. Evidently I didn't notice it there with my belly pressed against the bench, even after I flipped the power on.
Fortunately I was able to make an adjustment quickly enough to prevent completely par-boiled juevos; we're still a little tender, but we'll live.
So take it from the old tinker-dwagon... just because your alter-ego is fireproof, doesn't mean YOU are.
PAY. A. TTENTION!mnem