Supplemental files... DG-10 to DG-20 MIDI conversion

Ok...this is simply going to be all the files...I will try to organize them by section...starting out with the MIDI conversion.

This is what I used to do my mod.

First it is very handy downloading the DG-10/20  Service Manual available many places... 

On all the documents I annotated the original wiring in red (so I could follow the circuit) and my changes in pink (basically as an assembly manual).

The most time consuming part was the re-engineering...but soon I realized that the schematics almost exactly matched the circuit board...so you could almost lay the schematics over the board to identify parts.

In my reverse engineering I reversed the pictures of the bottom of the circuit board so it would directly match the top of the board...and the schematic...it makes sense once you try it.  As a result some of my notes are in backward writing, but it is easy enough to figure out.

Lets start with the schematic.  

First starting with the MIDI port on the DG-20.  There is a switch to either have 6 channels out...or just all 6 strings to one channel.   Second is the port itself.   Note the identifiers JG-1 through JG-6  This is on a daughter board at the IO jacks...I had to just wire it up direct.  (BTW the item marked FB...those are ferrite beads) (I used DigiKey part number 240-2513-1-ND Ferrite Bead 86 Ohm Axial)  Also on the circuit below, there are two things that look like black circles spit in half...they probably match something on the circuit board that would have been mounted on the DG-20...I couldn't even see a photo of that board...the fully split in half one means not connected...the one with a small line in the middle is connected...

 Now on this schematic on the upper left side you again see JG-1 through JG-6 , these are the drilled holes in the DG-10  circuit board...they aren't marked...and I did have to modify them a bit...but it is almost 100% there.  So I ran wire from those drilled holes to my MIDI connector and switch.

Now you will note on the DG-10 schematic the obvious missing JG connection.  You can see in pink the required mods...one specific one tells the CPU that it is a DG-20 not DG-10

So here is what it looks like on the DG-10 circuit board.

 Inverted backside with mods  You will note I marked the connection 1-6 on the upper right side.

BTW all the jumpers and components go on the top...but it was easier to follow the circuit by drawing it out on the bottom of the board.

Actual view backside with mods, again red is existing wiring, pink is my mods.

These photos have ALL the mods in view, not just the MIDI...so just using the schematic, knowing where i marked pin 1 and 6, just follow the lines... There is one wire to remove, a resistor to add, a diode to add. and a handful of jumper wires to install...almost everything goes into existing drilled but not marked holes.  Now for the pic below, note the wires at the lower left of the above pic.

 Here is the only circuit trace you have to cut...right there in the center of the pic above next to "JD" you see I have a pink line and 3 white lines...that area is one big circuit trace, so I had to cut it where those lines are to separate the area into separate traces...the white is where I dug through the copper trace to bare circuit board below.

Finally I needed to know what pin is what for the MIDI connector.

Going slow and using a voltmeter in 'resistance...beep' mode I went through it line by line, making sure I had a match from the schematic to my DG-10 wiring.

Casio DG-10 modified into a DG-20

So if you were a rich kid in the 80's you might have had a DG-10 or DG-20 a digital guitar made by Casio.  ($350 for the DG-10...I am guessing the DG-20 was $50 to $100 more)

I was not a rich kid in the 80's and I hadn't even heard of this until I saw one on the remake of the Take On Me video by Weezer.

So I did so looking around, figured out what the device was, then tried to by one.

I lucked out and picked up a DG-10 (like in the video)  that needed a bit of work but operated just fine...for dirt cheap...

So I got it running and played with it a bit, as I dug through the documents available I learned that I had the stripped down version, but there was also a DG-20 that had line out and MIDI out. (as well as some other sound and manual percussion switches).

Well I was jealous of the MIDI output...so I popped mine open to see how hard it would be to modify mine to add MIDI support.

I noticed that in the Service manual that the main parts seemed to be identical and even the circuits were almost identical except for some minor differences and some passive components.

I took pictures of the circuit boards top and bottom and happened to find a few pictures of a DG-20's guts.

I realized that those geniuses at Casio had built both keyboards with the same chips and almost identical circuit boards except for about 3 modified traces...depending on which version you got, some traces were whole and some were cut.

The circuit boards even had the drill holes...the only thing missing was labeling and some of the pads were coated and had to be cleaned.

So based on the schematic (they did not have board photos unlike most electronics service manuals) I basically reverse engineered the circuit boards and figured out where to add passives and jumpers, and where to remove them to convert the DG-10 into the DG-20.

(luckily mine is a DG-10 so no worries)

I can say that it was actually an easy mod...time consuming for the planning and reverse engineering, but the actual mod went pretty quickly with no problems, except for missing a jumper, and 4 passives for the line out circuit.

So the total number of parts required for the mod were:

1 slide switch
1 midi port
1  1/4" mono port
8 momentary pushbutton switches 
4 ferrite bead filters
9 diodes
3 ceramic capacitors
3 electrolytic capacitors
6 resistors

So depending on what you have on hand...$10 to $20 worth of parts...you know the Casio factory got them at bulk...so I am guessing the DG-20 cost at most $5 to $10 more to build...total cost. (some more rubber switches, two more circuit boards, and a completely different sound selector in the actual DG-10)

The result is other than how the switches and outputs look, my DG-10 is a DG-20.

I am sure nobody else is dumb enough to do this mod, but I include the photos I used and modified to show the original circuit and components and the ones requited to modify the DG-10.

I will say you don't really need the line out, but I thought bypassing the amp circuits might sound better?

Anywho the following are my modifications to the board photos I did.

 Lineout mod to schematics (not complete...just showing what I missed...

In all cases the pink (salmon?) colored lines are what needs to be added or modified, the red is the existing circuit topside components (to help me trace the circuits)

Amp circuit mods to get line out

Tone control and rhythm select panel...needed to be modified to add 4 tone switches.

If someone really gets a desire to do this mod, drop me a line and I will send all my photos and documents...

Collidoscope...A Granular Audio Synth

I was watching random videos and stumbled on this one by Dr Mix.  (this is their prototype, not my version)

So I thought it had a great look and interface, but couldn't imagine how expensive it was.

...it isn't...

This was a project by two people (I assume students at the time) at The Queen Mary University of London.

It operates of a Raspberry Pi, two USB/MIDI keyboards, 4 slider potentiometers, a Focusrite USB soundcard, an arduion Teensy, two microphones and a monitor. 

To make it pretty you build a box.

Their project site has full documentation on the wiring, software, and even hardware.

there are a couple of howevers.

-First, the software was last updated in 2016.   They have a compiled app at the project page that works just fine, but if you want to make any changes...well lets just say I have been neck deep in software for the last few days.
-Second, most of the pictures and explanations show the original version, the plans demonstrate the later version...can cause confusion.


So a big part of their project was the Collaborative concept of separate keyboards, microphones, and sample manipulation.

For now I am simply building a single person version...so I only have to source half the hardware from ebay...
...but I had to modify the software...

If you notice in the video,  you see two wave forms...but they are both on a single monitor.   I wanted to make a single user version and only show one waveform on the whole screen.

If I had done this back in 2016 it would have been a simple text edit and recompile.   However, the compiling code changed quite a bit from then and it was far from a simple text edit.