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.

An abscessed tooth really puts me off the map, being able to see straight seems to be a crucial element to my process. I'm back now, will probably take me a short while to get back into the swing of things.


I played a show last weekend, in my less than fully functional state, which led to a few modifications to my approach. First: I never got around to digging into my TOA RX-212, so my Fender 4216 was rotated into the set up. Second: I forgot the PSU for the tube Tektronix 161 and 162 modules seen center rack, meaning an entire branch circuit of my set-up was inoperable, and I could have essentially left a rack at home.

The first bottleneck was the clincher, as four oscillators, distortion, pair of ring modulators and the H-3000 is more than enough to pave a huge set. A huge sound seems to reveal headroom issues with the Fender desk however, as all presence and clarity was brutally stripped from the wash leaving an undefined murk coming out of the speakers.


I think this is shortly before I removed the tape machine from the equation, since the Fender console does not support simultaneous 1/4" and XLR output feeds I had run XLR output to the Otari for recording and daisy chain its outputs to the PA. Troubleshooting my sound quality, demanded removal of the tape deck, which was no great tragedy since my set was less than satisfying up to that point.

As it turned out, the Otari was not the problem, and only through ripping out my low end and leaning on HF (with the aid of a mechanical alarm bell) was I able to move around a little bit in the audio realm.

More fuel to repair the TOA, and inspiration to crack the case on the Fender and see what I can learn.

(Thanks to Heather Chessman for second pic)