Korg DJ Mixer Crossfader Woes

[Timmox]

Hello everyone,

First of all thank you for taking time to look at my problem. I’ve quite a lot of experience repairing electronics with relatively simple issues. However, this one is seems to be a bit more complex and beating me at the moment.

The offending bit of gear is the 2002 Korg KM2 Kaoss Mixer. The main issue is when the crossfader is fully left it only reduces the level of Channel 2 to around 75% rather than 0%. If you move the crossfader to the right it cuts level from Channel 1 to 0% as you expect.

Of course, the first thing I did to remedy this problem was replace the crossfader. The replacement was purchased from Korg UK who amazingly had it in stock. This however did not resolve the problem.
I then set out to try and find the service manual online but to no avail.
After some probing, I came to the conclusion that the audio signal probably doesn’t actually pass though the faders and they are more likely remote controlling preamp with voltage. With this in mind, I traced all the faders back to a HC4053 Triple 2-Channel Analog Multiplexer IC. So I replaced this but sadly again it made no difference.

At this point I thought I am out of my depth now and should get some advice.

If anyone can offer any advice it would be gratefully received.

Thanks in advance,

Tim.