SuperJX Jack Board

The Jack Board is often overlooked in an instrument and can be the cause of many issues such as MIDI interface not working, outputs with different/low volume levels or distorted sound.

This guide shows an MKS70 but same issues and techniques are applicable to the JX10.

To try and get around issues, people sometimes  contaminate it by using switch cleaner on the sockets. This can then leech into the nearby connectors over time and cause failure of the wiring harnesses and jack sockets. Contact cleaner is oil based and although it works at first, it is short lived and causes resistance and diode junctions to form at the contact points thus impacting the sound.

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Dry Solder Joints

The most common issue is dry joints. In the example below, the contact to the jack pin is completely detached. The example below isn’t too serious but leads to intermittent operation, hence why a technician had wrongly blamed the socket and used contact cleaner.

However, if the solder joint is bad around the switch contact pin, then outputs become wired together thus impacting the sound quality dramatically, often leading to perception of low output.

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Jack Sockets

Many of the jack sockets are by now corroded or contaminated. They can be replaced by sourcing them from   KBJA63-5012PM.

  • Roland part: YKB21-501
  • Description: phone jack 1/4- 6.3 mm for
    printed circuits Mono

They cost around 2 Euros each plus tax and shipping.

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They are best replaced. This means removing and replacing the sockets and reinstating the tension on the grounding clips to ensure noise free operation.

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First place sockets in the PCB and attach the rear mounting plate loosely but enough to hold them in correct position together. Ensure that the bodies of the sockets are completely flush with the PCB.

Put a small amount of solder on one pin each to hold them in place. Then melt each one in turn whilst pinching the jack socket and PCB together to sure that no gap remains.

This ensures that the joint is supported by the body of socket and PCB. The solder joint would otherwise experience high stress when mounting plate is tightened or a cable is inserted.

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Once everything is properly aligned, all solder joints can be made but miss out placing solder where the ground springs go.

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Loosen the fixing nuts and tilt the metal panel.

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Whilst holding the gap open a little, attach the grounding springs and solder in place.

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I prefer to clean up the PCB at this point but great care needs to be taken to avoid resin and dirty cleaning fluid getting on the connectors. Once cleaned, remove all residue off the fixing points that are used to ground the audio.

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Tighten the nuts on the jack sockets and it’s ready for installation.

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Copyright © 2020   Super Synth Projects, Guy Wilkinson