I bought this DAP mixer in 2022, and in the two years between than and writing this article it has worked well. I made a video about it on YouTube explaining how it really is a versatile bit of equipment, and when the source selection on my vintage Braun A1 amplifier failed (cracked plastic gear) I routed all of my audio through this mixer.

However, In the last few months I have noticed that the latching switches have been sticking, resulting in inputs or outputs remaining on after I had switched them off. The lights would go out, indicating that part of the switch is off, but the audio might remain in one or both channels.

I couldn't find any images or diagrams online to indicate exactly how this was built, but I knew these must be mini latching switches that could be serviced and possibly replaced with better quality items. With no other options, the warranty already expired and the problem really starting to annoy me, I decided to dive in and have a look.

As you would expect, the first thing to do is remove all of the knobs and slider caps. If possible, keep track of where the knobs came from instead of just throwing them all in a cup like I did, as the keying varies and it'll be trial and error to get the right one later! It would be easier if they were all turned down to their lowest settings, but I didn't want to mess my mix settings up...

The front panel is held on with seven screws, there's a sneaky extra screw below the aux RCA jacks. The seventh screw is different from the others, being a pointy self-tapper instead of a machine screw. This same front panel doubles as the rack mount bracket, so remove it from the mounting (brackets in my case) before removing the panel. I'm fortunate that all of my cables have enough slack for me to stand the unit up on my desk, in an actual rack mount situation this could be much more fiddly.

When the panel comes off, the translucent white buttons will try to fall out. This isn't catastrophic but keep this in mind as you need to put the panel back on without them all falling out, ideally by tipping the unit forward. Best plan ahead for this. Try not to lose any.

The inside in all of its glory. Ever taken something apart and instantly regretted it? Thankfully that only lasted for a moment.

Each switch has a little transparent piece that sits over the switch and LED, to be pushed by the front panel button. I don't like this very much as the front panel buttons are loose and can move around, but it works. These can be removed to access the switches. I removed the board on the right, which houses the LEDs for the three LED output meters and is held on by another two screws and then unplugs. It's easier to remove and re-fit the transparent plastic parts of input 5 without this in the way.

With all the transparent pieces removed, I could see little gaps into the switches. This is probably where dust has got in, I doubt the 45 degree mounting angle helps in this respect.

I then reached for my DeoxIT D5, spraying a little into each switch and turning it on and off around ten times. Having looked around and decided that I can't see any exposed high-voltage electrics, I then re-fitted the LED meter board and reconnected the power to test it. I was satisfied at this point that the contact cleaner had done the job and I could re-assemble the mixer.

Reassembly, as they say, is the reverse of disassembly. First the plastic pieces go back on, they just push over the stem of the switch and the LED pokes through the hole. As mentioned previously, the best way to fit the front panel is to lay the mixer on its front, or at least a very acute angle, so the translucent buttons can't fall out. Once on and held on, it can be tipped upright to fit the screws. The stems of the potentiometers and the white input selection buttons will kind of hold it in place.

Refit the screws, the slider caps and the knobs. Oh and if you've unplugged the power for re-assembly (which you should always do) then don't forget to plug it back in before re-mounting, especially if you can't get to the back of it afterwards. Ask me how I know!

You should now find that the inputs and outputs turn on and off perfectly, with no sticking. It's only a couple of weeks since I did this but I have faith in DeoxIT and know this process if it needs to be done again.