Gave the Fender MX 5216 a quick run through, cleaning switches, as they were acting dodgy and this unit may be rotating out into a new home.

Working surface, after I'd dropped the PCB off each sub-section. While I had open metal, I took the opportunity to wipe it off.

Original buildup.

Each sub-section houses a horizontal circuit board with duplicate circuits, lots of ribbon cable.

Everything is pretty easy to get at, and through hole construction. Built in the mid 1990s, when miniaturization was really getting a toehold.

I'm guessing this could benefit from a recap. I'm not tackling that one right now, but at 10 caps a channel it doesn't look too terrible even if the pots outline an obstacle course.

Per channel breakdown: first stage is a SSM2017, TL072 is seated in the EQ section, NE5532 in the Aux send section, MC14053B in the output routing section and an NE5532 acts as post fader recovery. The summing section is populated almost entirely with NE5532.

When I bought this in ~2007, two of the input channels were non functional. As it happens, the input trim control pots had popped apart, it was a matter of realigning and tensioning the metal legs to hold it together.

One of the ribbon connectors popped free unlabelled, and since several of the header connectors at the board are not populated, I had to reverse engineer the connection. Reading continuity at Aux send 1 & 2, it became reasonable to conclude it belonged at the Aux send 1 & 2 block.