Surgery on Rane MQ302s stereo “mojo” EQ


having a background in live sound, I maintain a relationship with hardware garphic EQs. They are THE TOOL that I learned for knowing and controlling frequency problems (like feedback) or for shaping the EQ of a sound to sit clearer in a mix.

I didn’t like the disconnect of only having access to (hands-on) hardware graphic EQs at work, and then only using software (visual, virtual) software EQ plugins at home,.

So, in 2014, I found an bought a cheap (kind beat up) Stereo 30-band graphic eq to keep on my master outputs at my home computer.

Rane’s MQ302s is the stereo version of their 30-series eq, and in the DJ-marketed “mojo” line.

Image result for rane MQ302s
the rane MQ302s, from their (more affordable) “mojo” series (for DJs)

This allows me to

  • practice my aural/muscle memory for a 30-band graphic EQ for live work.
  • sniff out sounds of interest in any mix by frequency, then adjust things upstream (in software)
  • listen to how much isolation or blending of sounds in various frequency ranges.

Nice idea, if the one I bought fully worked…


…but The one I bought had broken knob/tabs on 3 band-faders…


Image result for rane mQ302s broken
I did not take a picture of MY broken faders, but here’s an example of how easily/common it is for these exposed, unsecured plastic fader-tabs to snap off.

On my unit, the broken controls were for

  • 25 Hz (the lowest band)
  • 31.5 Hz (the 2nd to lowest band)
  • 1.6 kHz,

Everything sounds fine, I just need to replace the slider-potentiometers inside to regain control of these bands

To the Bench

I didn’t take many pictures of opening or disassembling the unit. Everything form the power and audio IO on the back to the switches and band-faders on the front is on a SINGLE board, mounted in a 1U chassis.

After getting that open, I see the biggest hurdle in servicing individual band-faders; the slider-UI board is mounded by MANY thick pins.

I had to desolder ALL of these pins just to remove the slider sub-board in order to get a good look at the specific part before I order replacements.

the main board, showing the slider sub-board, after I desoldered the anchor-pins.
lifting this thing off was NOT fun or easy..
as you can see, each slider-pot has 3 pins (hi, wiper, low) and there are only 2 Anchor-pins per band slider. I don’t know if these are work ing as rheostats or as CV, and I didn’t want to decommission the unit any longer to study it…


Here we can see a bit more detail on the trace the set the 3-pin slider pots into the 2-pin/channel anchor leads.

American Made, American Customer-Service

However, after my initial frustration finding that component online, it dawned on me that I should ask Rane about service. I called them up, and they charged me less than $20 bucks to send out 4 of their parts.

WAY TO GO Rane !

Back to the Bench !

Now that I had the right part, I pulled out the broken sliders…


pulling out the broken 25 Hz slider

And eventually got them all out.


a “smile showing all the missing teeth”

And soldered all the new/good sliders back in place.

a perfect(ed) smile

…and the UI slider board was good as new.


Back in Action:

I put the unit to the test on a new variation of my drum-machine setup, using the Korg ESX to push out all kinds of pure-tones and gnarly drums all across the frequency spectrum.


Yummy !

Afterward, the unit was promoted to my upstairs office computer/mix desk, where it will be safe from rough handling or falls that might break its precious and delicate faders.

I keep my Rane 30 band EQ right above my keyboard, front and center…

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