1) Be sure to have the correct tools and supplies for for the job. If you do not have them, get them. You will need a regular size Phillips screwdriver, a smaller size Phillips screwdriver, needlenose pliers, wire cutters or other flush cut nippers, a hobby knife such as an X-Acto, scissors, a soldering iron, solder, electrical insulating tape, and a black Sharpie permanent ink marking pen. If you intend to mount the DIN jack on the back panel with the rest of the jacks (highly recommended), you will need to use a chassis punch (a small hand tool that safely cuts a clean hole in a metal panel) to make the hole for the DIN jack, and an electric drill with a 1/8" or similar size drill bit to drill holes for the 4-40 hardware used to mount the DIN jack, and also a 1/4" or 5/16" drill bit to make a pilot hole to start the chassis punch. The correct size for mounting a MIDI DIN jack is 14.5 mm metric or 5/8" SAE (.62"/15.9 mm) in American sizes. A chassis punch may be purchased from any good tool or hardware store. If it is more convenient, a punch may be mail ordered via internet or telephone from Mouser Electronics at http://www.mouser.com or (800) 346-6873. The Mouser part number is 586-3803 for the name-brand Greenlee 730-5/8 (about $30). The cheaper house brand part number is 380-0145 (less than $20). The service from Mouser is unpredictable and the house brand ordered by Synhouse for the test installation took three months to be delivered, while the Greenlee part was delivered in one week. Mouser refused to give even a small discount to customers of Synhouse, so no recommendation is deserved or being made here, and any other source you know of to buy this type of tool is highly recommended and certainly a better place to buy from for all of your needs now and in the future. You will also need an 11 mm wrench (for Greenlee) or 1/2" wrench (for the Mouser house brand punch) or adjustable wrench to turn the chassis punch while cutting the hole. An automatic center punch would also be useful. This is an inexpensive spring-loaded pointed punch that can mark your drilling spot without the use of a hammer. Marking the holes with this small indentation will allow you to drill cleanly without slipping and scratching the synthesizer or drilling through your knee.
2) Fully test the Korg Mono/Poly to be converted to MIDI. Be sure that all functions such as the envelope generators work and that the instrument plays in tune while playing along with a known well-tuned instrument such as a newer digital synthesizer or sampler keyboard. A Mono/Poly often requires 30 minutes or more to warm up and play in tune. If it doesn't work properly without MIDI, it certainly won't work with it.
3) Extreme caution should be taken while working on the Korg Mono/Poly. The unit should be unplugged while open and even then, the power supply may pose some electric shock hazard due to residual voltage in the power supply.
4) Remove the seven Phillips screws that hold the top panel in place. Two are on the front right side, two are on the front left side, and three are under the back edge of the synth, going through the crumbly old particle board. Lift the top panel and set it back on its' rear, being careful not to stress the wires that are still connecting the two.
5) Turn the synthesizer to the side or upside down and shake out any dust and debris that may have accumulated inside the instrument over the years.
6) Determine the place where the
MIDIJACK circuit board will be mounted and test fit the board into its'
correct place inside the case. Be careful to avoid putting the board
or wires near the high voltage connections in the right rear of the instrument.
Mark the correct mounting holes on the panel with a pencil, marker,
or needle using the paper drilling template provided with the MIDIJACK
hardware packet. In the example photographed here by Synhouse,
the Original MIDIJACK circuit board is mounted inside the plastic box which
house the modulation and pitch wheels. A photo called MonoPoly-pic1
shows the paper drilling template in place:
8) Determine the place that the MIDI
input DIN jack will be mounted. A good place to mount it is on the
back panel to the lower right of the OUTPUT jack, as photographed
in this example. There is a lot of room on the rear panel of the
Mono/Poly, so you may mount the DIN jack wherever it suits you best.
Be sure not to mount it too close to the crumbly particle board sides of
the instrument, which have rear supports which would obstruct the
rear of the DIN jack. The Korg factory finish is a hardened coating
that may well chip and separate after cutting the hole for the DIN jack,
so it may be best to mount the DIN jack from the outside of the panel instead
of inside the panel as in a normal MIDIJACK installation. This will
conceal the somewhat jagged edge of the finish. To do this,
mark one of the two wires (#9 orange or #10 gray) at the terminals of the
DIN jack with a marking pen or tape to remember the polarity then desolder
both wires. Use the paper template to mark the correct spots to drill
and cut as shown in MonoPoly-pic4:
10) The MIDIJACK #1 black and #2
red wires must be soldered in place to get the ground and power for the
MIDIJACK. There is a ground terminal on each of the 1/4'' jacks as
well as a piece of buss bar wire which all connect to the sleeve of the
jacks and is grounded directly to the chassis. Solder the MIDIJACK
#1 black wire to any one of the ground points, such as to the buss
bar wire as shown in MonoPoly-pic7:
11) Locate the factory Korg brown wire which is soldered to the back of the CV IN jack. It is the terminal oriented to the right hand side and conducts directly to the tip of an inserted plug. Remove the wire from the solder terminal by desoldering it. Solder the MIDIJACK #3 blue wire to the now-empty isolated CV terminal.
12) Solder the MIDIJACK #4 white wire to the now-disconnected factory Korg brown wire. Carefully wrap the solder joint with electrical insulating tape.
13) Locate the factory Korg red wire which is soldered to the back of the TRIG IN jack. It is the terminal oriented in the upper direction and conducts directly to the tip of an inserted plug. Remove the wire from the solder terminal by desoldering it. Solder the MIDIJACK #5 yellow wire to the now-empty isolated TRIG terminal.
14) Solder the MIDIJACK #6 green wire to the now-disconnected factory Korg red wire. Carefully wrap the solder joint with electrical insulating tape.
15) Photo MonoPoly-pic9 shows the
inside of the rear jackpanel containing the analog interface jacks and
TRIG POLARITY slide switch with the MIDIJACK wires already connected to
the proper points. A look at this will give some idea of what it
will look like when done correctly:
17) The MIDIJACK hardware packet contains nylon cable ties which should be used to tie the MIDIJACK wires into little bundles and to attach them to the factory wires inside the Mono/Poly now that all connections have been made. This will secure the MIDIJACK wires to the inside of the chassis so they will not rattle and break loose inside the case once the instrument is returned to service.
18) Carefully examine all soldered connections for possible short circuits before closing the instrument. Before closing the instrument, it may be a good idea to use epoxy glue to reattach the loose crumbly particle board sides to the crumbly particle board base to help reinforce the instrument once it is put back into service. You may also use a bit of epoxy to reattach the loose end bits of fake wood veneer strips, but beware, once reattached, they will eventually pull loose again because crumbly particle board cannot be effectively glued to anything, especially even itself due to perpetual crumbling, which is why it is incorrect to say "pull loose again" because it was probably never pulled on in the first place. Who pulls on veneer? It falls off all by itself. It is difficult to decide which is worse about the Korg Mono/Poly: A) The unreliable "conductive" elastomer keyboard mechanism which needs to be cleaned repeatedly because it gets dirty without use or dirt, or B) The crumbly particle board construction of the base and sides. With the installation of the Original MIDIJACK and some epoxy glue reinforcement, both of those 20 year-old problems can be circumvented in most cases.
19) Close the instrument and secure it with the seven Phillips screws.
20) Test and calibrate using the procedures described in the Original MIDIJACK Quick Installation Manual.
21) This installation can be completed in approximately one hour.
The Korg Mono/Poly
has a trigger circuit separate from the gate circuit to provide multiple
note envelope triggering. This is not required for MIDI operation
because the Original MIDIJACK has special software to do multiple note
triggering like an ARP or single note triggering like a Moog. The
user can select either mode at any time. For this reason, set
the TRIGGER SINGLE / MULTIPLE switch to MULTIPLE. Since you are using
the V-trigger output from the MIDIJACK, set the TRIG POLARITY slide
switch to +15V.
Copyright © 8/7/2001 Synhouse Multimedia Corporation