Shropshire Lad wrote:I have a Makin/ Johannus organ. I'm struggling to identify what make or type the keyboards are except they are connected via a 16 pin ribbon connector. I have connected this to a MIDI boutique HWce2x board but only get 16 random notes out of the 61 working. The notes they play do not correspond with those on the keys. I have tried MIDIOX and currently only 16 notes are giving out a signal. Has anybody any ideas how I progress from here. I must confess my knowledge in these matters is virtually non existent!
Many thanks
It would sure help if you had more information about the keyboards. In the meantime '20 questions' is the way to find out.
1. Are they velocity sensitive ? (look at the organ's original specifications to determine.)
2. Is there 1 ribbon cable per keyboard ? (Are there more than one cable per keyboard or more than one keyboard per cable.
3. If there is only one 16 pin cable per keyboard and they are NOT velocity sensitive, it is possible to determine the matrix and the direction the diodes in the matrix are pointing, with a VOM.
When a key is depressed (start with note#1, slide a small wood wedge into the back of the key for the selected note to hold it down) there will be one row and one column connected together and a diode in series.
In an 8x8 matrix with the diodes in common anode, the keyboard switches will connect the cathode of the diode to a common point for the first 8 notes the anodes of the diodes are connected to select lines 1 thru 8.
By putting the Red lead of the VOM (set to measure resistance of 2k Ohms or diodes) on one pin and probing the other pins with a clip lead hooked to a small safety pin, you will find two pins that are connected together.
If not then reverse the leads and try again. Once the correct polarity is found and you have determined which pins are connected when the first key is depressed, record the pin numbers for that key. Go to the next key up and find the pins that are connected when that key is depressed. One of the pins in the second pair will be the same as one of the pins in the first pair. This is the common diode pin for the first 8 notes. Do likewise for the third key and so on for 8 keys. If it is 8x8 you will not need to move the common pin until you get to note #9.
The select lines will repeat every 8 keys (the pin for note #1 and note#9 will be the same. Likewise the pin for note #2 and note #10 will be the same. Once you have identified the 8 select lines for the first 8 notes, you only need to search for the common diode pin for the next 8 notes. You will need to depress only notes #9, #17, #25, #33, #41, #49 and #57 to find their respective diode common lines.
If you want the schematic of the matrix send me a PM with your email and I will send you a BMP picture.
Happy hunting!
Thomas