Having cut a swath of days to establish a system with which to record, I crawled through some of the obvious contenders for needing a bit of attention, built some cables and generally focused on foundation work so the actual recording process would be a breeze.
This process culminated with firing up my road worn TOA RX-212 mixing board, only to be greeted with a "GZZZZZZZZZ" mechanical buzz accompanied by dimly lit clip LEDs (which I attempted to capture above). It sounds like a starved AC relay that is opening and closing in sync with the 60hz wall voltage.
This desk has seen a lot of abuse. It was water damaged when I bought it in the late 1990s, and has since then been gigged. This unit has face planted onto asphalt after a show, bounced around in the back of a pick-up truck, van and Volkswagen. Clearly it's not a delicate high end flower for the studio, but aside from the occasional necessity of physically hitting it to wake a channel up or being hit with a huge bout of crackle at the lowest travel of some of the sliders this mixing board has been a solid element of my [view] set-up for a long time. All the idiosyncratic nuances meshing very well with experimental sound.
Here's evidence of the aforementioned water damage along channel PCB alignment fence, though the points where the aluminum shielding has dissolved points to a mystery.
Gutshot! All the benefits of independent channel strips without the ease of removal. The ribbon distribution cable was replaced with point to point solid core wire pulled from a length of CAT-5 in (IIRC) 2002, the stock header/ribbon connector system having decayed into a patina'd bluish mess that had given up on its original purpose, that of passing electrons. This modification, while saving the day in terms of functionality, has elevated pulling the channel cards for repair into a PITA nightmare realm. Should I have to dig back into the channels for anything I'll probably replace the connection blocks with something similar to stock, since I've grown beyond just thinking about what I have on hand that will make something work in the space of nine years. I've also grown beyond the notion of upgrading all the ICs, but that's beside the point.
Centered here is the rectification and voltage regulation board. I expect I'll be plucking that out of there and rebuilding it, should my suspicion of insufficient or dirty power be confirmed.
Over all, I like this board a lot (for its application). The fact that TOA designed interchangeability between the RX-208, RX-212 and RX-216 is apparent with the almost modular design, which is close enough to be annoying that it's housed within a monolithic control surface. On the other hand, had they gone the extra mile and built the enclosure to be modular, mine probably would have long ago stopped working and fell to pieces.