Fender M12

I never knew Fender did mixing desks but then out of the blue this one had to be saved from going to the scrapyard.

There were several issues

  1. PSU had a toast rectifier diode and burnt out stabilizer. I could tell there was somebody in there before me and added various modifications. One of them was extra huge electrolytic cap to get rid of the PSU induced hum. Thing is, PSU hum was there due to dried out electrolytic capacitors with massive dielectric losses so while this modification removed the unneeded hum the ever increasing load on the transformer and rectifier diodes eventually led to the diode failure and associated chain events.
  2. one of the meter  module opamps were toast and presented beautiful smelly smoke following the power up
  3.  few of the channels had a bad solder joints
  4. one of the channels had a bad OPAmp

When tackling vintage console the main question is that of economical feasibility of the repair

If things are to be done properly, every switch and pot taken apart cleaned and lubricated, every dried out cap replaced it takes enormous amount of time which will be worth several times the price of the console itself

With everybody moving to digital nowadays , there are high end analog consoles available for unbelievably low prices

However it was decided to rescue this vintage piece and 2 weeks of cleaning have begun

I stripped every channel, carefully opened every single pot and cleaned using three stage process First I remove the coarse debris with compressed air, clean all the contacts and pot track with Kontakt 60 contact cleaner, wash it down with Kontakt WL and finally lubricate with Kontakt 61 fader lubricant

Nylon scratch brushes were particularly handy in this effort

This before / after picture of the slider pot shows the difference thorough cleaning can make, all of the sulfides dust dried out grease are removed and surface freshly lubricated

Difference it made to the feel of the slider pots was quite eye opening

The end result is reliable vintage mono mixer with fairly high noise bed but it’s nice analog noise, nothing particularly irritating