Jen SX1000 Instruction Manual

JEN SX1000
MIDI Upgrade
Installation & User Manual
Neil Johnson
www.njohnson.co.u

Copyright © 2008 Neil Johnson.
All rights reserved.
First edition, February 2008. Minor corrections, April 2008.
For the latest version o this manual please re er to the website:
http://www.njohnson.co.uk/Jen/SX1000
Support questions may be sent by email to: [email protected]
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Contents
1 Introduction................................................................................................................ .....4
1.1 Features 4
1.2 A Short History 4
2 Installation..................................................................................................................... ..5
2.1 Preparation 5
2.1.1 Tools and Equipment You Will eed 5
2.1.2 Skills eeded for the Installation 5
2.1.3 Preparing The Workplace 6
2.2 Step by Step Installation- - 6
2.2.1 Opening The Jen SX1000 6
2.2.2 Removing The Keyboard 7
2.2.3 Fitting The MIDI Upgrade Board 7
2.2.4 Fitting the MIDI Socket 9
2.2.5 Connecting the Filter Cutoff 9
2.2.6 Calibration 10
2.2.7 Replacing The Keyboard 10
2.2.8 Closing The Case 10
2.2.9 And Finally... 11
3 Using the MIDI Upgrade............................................................... .................................12
3.1 Keyboard Playing 12
3.2 MIDI Playing 12
4 MIDI Implementation Chart............................................................................. ..............13
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1 Introduction
Welcome to a un new way o playing your Jen SX1000. As one satis ied customer put it so
aptly: “It adds a whole new world of playing when you can bend the notes”. This manual
guides you through the process o installing the Jen SX1000 MIDI Upgrade, and explains how
to use it.
1.1 Features
The MIDI Upgrade provides the ollowing eatures:
●Receive MIDI messages on MIDI Channel 1
●Responds to all 128 MIDI Notes
●Responds to Pitch Bend with ±2 semitone range
●Responds to Modulation Wheel (routed to ilter cuto )
1.2 A Short History
The JEN SX1000 was originally released in 1978, with production ending in 1982. The heart
o the SX1000 is a single voice organ chip, the M110 rom SGS ATES. Un ortunately this- -
chip is no longer made, and the design o the SX1000 lends itsel to stressing the output
drivers o the M110 amongst other things.
As a result, together with age, the M110 o ten dies. And once it is dead there is little you can
do but replace it, since as well as generating the basic tone the M110 also scans the keyboard
and produces the glide (portamento) between notes.
The impetus or this MIDI Upgrade was when I bought a non working SX1000. The M110-
was dead, and inding a replacement proved very di icult. So in the end I decided to design a
replacement using modern components. A micro controller emulates the main unctions o the-
M110, and adds a MIDI input so the SX1000 can be played by a sequencer.
Over the years the design o the MIDI Upgrade has been revised and re ined. Some eatures
have been removed, others re ined, and others added in response to requests.
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2 Installation
Installing the MIDI Upgrade to your Jen is a di icult task. But i you allow yoursel plenty o
time (2 3 quiet hours) and ollow these instructions then you should be able to do this task. -
Some important advice:
–DO NOT RUSH – take your time. Try to do this with no one else around. Put on some-
quiet classical music. Put your mind in a relaxed state.
–DO NOT FORCE ANYTHING – i something will not move or unscrew then stop and
work out why not. Do not apply all your strength, you will only break or snap a screw.
And that is bad mojo.
–SPREAD YOURSELF OUT – use plenty o space to lay things out as you go. Give yoursel
room to move.
The instructions are presented as tick lists. Follow each item in the list and tick them o as
you go. That way you can go away, and return to the installation and know exactly where
you were.
2.1 Preparation
As in all things, preparation is paramount. Be ore starting the installation please check
through the ollowing sections to make sure you have the required tools, the required skills,
and a suitable work place.
2.1.1 Tools and Equipment You ill Need
You will need to provide some tools yoursel . The ollowing list sets out everything you will
need to complete this installation:
□small cross head screwdriver-
□large cross head screwdriver-
□snipe nose pliers-
□pair o wire cutters
□wire stripper
□soldering iron
□desolder pump
□trimmer tool
□22 SWG solder
□permanent marker pen
□3mm metal drill
□15mm metal drill
□electric drill & sa ety glasses
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2.1.2 Skills Needed for the Installation
A combination o basic mechanical skills (drilling and iling) and electronic skills (soldering
and de soldering) are required. I you do not possess these skills then I strongly recommend-
inding someone who does. Otherwise you may end up damaging your synth.
2.1.3 Preparing The orkplace
□Unplug the synth rom the electrical socket. Do not just turn the socket o – you need to
actually unplug the cable rom the power socket.
□Place the synth on a dry, so t sur ace, or example a table covered in a large towel.
2.2 Step by Step Installation- -
Once you are all set up and ready to go, proceed with the ollowing steps. Throughout these
instructions it is assumed that the synth is arranged with the keyboard at the ront, as shown
in the picture below.
2.2.1 Opening The Jen SX1000
□Care ully turn the synth over and rest it on a cloth or pillow.
□Remove the two keyboard screws near the ront o the synth and them and keep them sa e.
□Turn the synth so it is acing up.
□Remove the six ixing screws that hold the main panel to the wooden base. There are three
on each side, with one on the ront and two on the rear. Keep them sa e in a tin or bag.
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□Care ully pull the ront panel up and away rom the ront o the synth. Move it slowly,
being care ul o the bundle o cables connecting the panel to the main case. It is
recommended to rest the metal panel on the rear ace. Use a towel or pillow to protect it.
2.2.2 Removing The Keyboard
□Remove the two or our screws holding the keyboard in place.
□Move the keyboard mechanism towards the ront. The connecting cable is on the right
side.
□Slowly turn the keyboard over on its right side so that the underneath is acing upwards.
You should now see the M110, as highlighted below.
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2.2.3 Fitting The MIDI Upgrade Board
□Using a permanent pen place a mark on both parts o the connector. This will help you
replace the connector the right way round later on.
□Unplug the cable rom the keyboard PCB.
□Using a small cross point screwdriver remove the screws that hold the PCB to the plastic-
keyboard rame.
□Slide the PCB towards you so that the 37 spring contacts slide out o the keys.
□Place the PCB on a lat, irm sur ace.
□With a medium sized lat screwdriver care ully prise out the large M110 chip rom its
socket. The best method I have ound is to lever it up a little bit at each end in turn, slowly
working it out o the socket. Put the chip is a sa e place.
□Turn the PCB over.
□Desolder the IC socket used or the M110.
□Fit the new IC socket. Solder each pin, making sure there are no solder bridges or dry
joints.
□Remove the six 5k6 resistors (blue green red gold) that sit next to each other in a row next- - -
to the IC socket.
□Re attach the keyboard PCB to the keyboard rame. It is a iddly job as all 37 key contact-
springs must be re aligned with the small holes in the keys. Any springs which are not-
seated in their locating holes can be itted with long nosed pliers, making sure you do not-
squeeze too hard and squash them.
□With the keyboard on a lat irm sur ace bring the MIDI Upgrade board to sit on top o the
keyboard PCB. It should be arranged so that the connecting wires ollow the same
direction as the connecting cable disconnected earlier. The photo below shows the general
arrangement (this is an older version o the MIDI Upgrade but the alignment is the same).
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2.2.4 Fitting the MIDI Socket
□Decide where you want to it the MIDI socket. The recommended location is the bottom
right corner o the rear panel (looking at it rom the back).
□Drill a single 15mm diameter hole in the rear panel, plus two 3mm diameter holes each
side to match the socket supplied.
□Fit the MIDI socket into the rear panel using the two black screws provided.
2.2.5 Connecting the Filter Cutoff
□Solder the single wire rom the MIDI Upgrade board to the ilter CV mixer. A good place
is on the le t lead o the resistor as shown in the picture below.
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2.2.6 Calibration
BE CAREFUL – MAINS VOLTAGE present inside the synth when it is turned on
□Connect the synth to a loudspeaker via an amp or mixer, or to an oscilloscope.
□Connect the mains.
□Turn on.
□Switch to Pulse, 50%, no PWM modulation.
□Play middle C and adjust the trimpot on MIDI Upgrade -board or a sound closest to
square wave. On the 'scope adjust or best shape closest to a square wave.
□Turn o and disconnect rom the mains power socket.
2.2.7 Replacing The Keyboard
□Turn the keyboard over and slide it back into the wooden base.
□Re it the screws inside the case (Section 2.2.2).
□Using the cable ties provided tie down the MIDI and Filter modulation wires, keeping them
away rom the metal heatsink on the power supply.
2.2.8 Closing The Case
□Replace the ront panel back on the wood base (Section 2.2.1).
□Replace all six black panel screws.
□Turn the synth over on to its ront and re it the two keyboard screws.
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