Korg A3 Jack Maintenance and Replacement

Posted: 2011/10/27 in Edge Effects Units, Korg A3

The Korg A3 is now famous as being one of the main effect boxes used during the Achtung Baby and Zooropa sessions.   With the 20th anniversary of Achtung Baby fast approaching (hard to believe!) these old units are definitely showing their age.  One of the most common problems they have is a tendency to develop loose solder joints which at the rear input and output jacks.  This is because the Jalco 16PJ500/16PJ509 jacks are attached to the circuit board in a rather flimsy way – they are soldered to the board, but there is no nut used on the rear panel for strain relief.  Eventually, after plugging in and unplugging phone plugs many time, and/or moving your A3 around in a rack to various venues and rehearsals, etc., those old connections break.  You can wiggle the phono plugs and it doesn’t give you a good feeling.  The result is that your A3 eventually cuts out on you.  (For some reason, usually this happens sometime after soundcheck when things seem to be working fine but right before you play Mysterious Ways…).   Don’t feel too bad – Sometimes bad stuff like this happens to the Edge, too… (“Edge, did someone break your funky thing?”)

A good way eliminate this problem and to make the A3 more rugged is to replace those Jalco Jacks with something you can mount to the rear panel using a nut, and then connect wires to the circuit board.  This way there is no more stress on the circuit board from the weight of a heavy 1/4″ phono plug.  The space to do this in is not very big, however.  The most convenient jacks I’ve found for this (so far) are the Neutrik Slim Jacks.

Neutrik Slim JackThey are made for PCB mounting applications, but that’s OK.  The soldering pins are big enough for you to solder a wire to.

Here’s a friend’s A3 I did some work on, with the original Jalco jacks visible:

The next step is to carefully desolder them.  I use desoldering pump to do this and its has been a problem.  Sometimes it helps to add fresh solder (with its flux) when desoldering old solder.  Here’s the board with the jacks removed:

Now one can position the news jacks to see how they will fit:

As you can see it will be a tight fit next to those inductors/ ferrite beads.  One of them has to be turned on it’s side. Because of space constraints,  I’m not going to replace the “Direct Out” jack (it’s rather useless).

Now solder some wires to the jacks. I’m using 22AWG wire here:

Then solder the wires to the board:

To keep it simple, the ground wiring (black wire) is only connected to the board in one place.

Here are the old leftover jacks after being removed (By the way if you need to buy these, you can get them at Mouser.com. They are part number 16PJ500 or 16PJ509 under the brand name Kobiconn):

Finally, here’s a view of the back after everything is put back in it’s place. Don’t worry about the open hole – there’s an easy fix for that…

You can get little plastic plugs at the hardware store which will pop into place and fill the empty hole in the rear panel.  ( It would have been better if I had found a black one, but it’s only going to be at the back of the rack…):

Now this A3 is going back home, and hopefully it’s wild flanger sounds will make it’s owner comfortably “Numb” for many more years to come…

  1. ANdrew says:

    Thanks for that. I have the A2 and its great – a wee bit temperamental though.
    Great footage – glad to see it happens to the pros’.
    Recently, I had an epic FAIL as my whole rack cut out. I was left with a Tube-screamer and a Clean boost. Nobody even noticed!! Not even the rest of the band. I’m glad I try so hard to get my tone just right!!!

  2. trabantland says:

    I know it’s true Andrew– we guitarist obsess about the smallest changes in tone that non-guitarist usually don’t notice. It’s good to keep that in mind when technical glitches happen while performing, because inevitably they will.

  3. Albert says:

    do you know if exist the on/off button?¿ I lost that and i’m looking for a new one

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