RE-EQUALIZER HUM PROBLEM
We are aware of only one instance of this happening. You experience hum, maybe after owning the device for some time. If you switch to BYPASS, the hum goes away.
FIX ONE
Remove the top cover and make sure that the indicated screw is not loose. Tighten it slightly to snug it up. If you can have the unit actually operating and while you are listening, you can instantly confirm the validity of the the fix.
The problem is actually caused because we painted both the inside and outside of the case. The paint usually gets cut thru when we assemble the PCB to the case, and the PCB makes good contact with the case.
FIX TWO
The above fix does not work, or is a bit intermittent. In that case, you have to scrape the paint of the top of the PEM nut that is pressed into the case.
First, remove the two screws holding the PCB to the case.
You have to remove the two knobs with a small screwdriver, then carefully, so as not to scratch the panel, undo the two large nuts holding the front panel on.
Next, you remove two more large nuts.
Now you can pull the PCB back to get access to the the standoff, PEM nut.
Scrape off the paint from the standoff.
Reassemble all.