An 8 year update. I almost killed all of the LEDbrick units due to a dinoflagellate-induced-light outage. Upon firing up the lights three days later, I had neglected to consider that being fully powered down, no heat was being produced anywhere, and condensation combined with 8 years of salt spray had worked its way into everything. Firing up, I got a nice bout of zap zap flicker flicker nothing. Oh no!
(The main tank is in a period of half-teardown and cleanout and reboot- its had 15 years of continued operation and the sand bed had gotten to dire straits amongst other imbalances, so no tank pictures)
When I had first built them, I didn't do any real control for salt spray, air, condensation, etc. The PCBs sit right in the air flow, and the case fit was never really designed. Going forward, remember to conformally coat all the boards to avoid this very issue.
Anyway, one of the lights as fine, because its logic part remained powered up due to an earlier salt spray mishap which exploded the 24V->12V regulator sometime at the start of the pandemic, which I bodged fixed with a 12V wall-wart. How bad does the salt spray get? Well, bad...
Yikes. Amazed anything works after all. And this is the working unit, since it never had water condense on it.
Other units didn't look _as bad_, but were non-functional due to numerous shorts across the board from salt. Amazingly not an amazing amount of corrosion.
Well, I'm happy to report that I managed to save 2 of the 3 units by doing nothing but giving multiple passes in the ultrasonic cleaner, with an alternating routine of
Branson EC and just RODI water - about 5 washes with changing the solution after each pass to not let salt concentrate, followed by a drying pass in an elevated temperature (about 60C).
And... success. And they look a whole lot better and almost like new.
Unit #3 had a hard failure and the 12V regulator also wouldn't come up. Unlike the bodged unit still running, the board was salvageable, but the failure eventually came to a shorted ceramic capacitor and an inductor which also had shorted internally (so its basically a wire). A quick repair job later with a similar small but not exact set of components:
So, whats next? I need to give the boards another clean and give them a quick coating of
conformal coating before reinstalling, and then, actually think about replacing them sometime this year. I have some ideas, for the next post...
