Johannus Opus 1200 conversion

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...
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mattrix
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Posts: 29
Joined: Tue Dec 06, 2022 1:35 am

Johannus Opus 1200 conversion

Post by mattrix »

Hello,

Does anyone know what midi encoder I need to purchase to make a Johannus opus 1200 work as a standalone console?

https://hq.globalorgangroup.com/service ... organId=49

It has midi already but the circuit boards are getting very old and unreliable and would like to use it as a simple non audio generating console for HW.

The console and pedal board uses 16 core ribbon cable IDC connectors and I was hoping that there might be a cost effective way to make the keyboards (2) and pedal board connections to a new midi board...using these connectors!? Not critical but helpful! However with the idea of connecting a further 3rd manual would be good. The new manual may or may not have these type of connections of course. There is enough physical room to add 1 more manual with the stop jam removed and take a bit out of the top wood frame for clearance and relocate the music rest back a bit from the front....

The stops are also on the same 16 core IDC plug but they and the expression pedals (just a few wires going to the amps) don't have any midi activity with the onboard circuit boards...even though they are connected to the same midi? board on the organ circuit boards.... If adding a 3rd manual then I wouldn't have room to have that stop jam anyway so that's not so important....

Further project would be to add pistons below the manuals again in Johannus wisdom these are not midi and only affect onboard combos and such.... What would be a good replacement for the pistons that would fit in those holes and or similar + more of them...?!

Lastly there are a few pedal notes that don't work - the magnets are still there and what seems to be reed switches on a circuit board running along the back strip - could it just be the switches or dry joints ???? Working up from bottom pedals that don't work are Low C, Ab E high C and E - is there any correlation here?

Thankyou kindly for any assistance - im a bit out of my depth here.....! I'm in Perth Western Australia and as such none of this sort of equipment is here local....!

Regards,
Matt
rayjcar
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Posts: 123
Joined: Mon Mar 17, 2014 9:56 am

Re: Johannus Opus 1200 conversion

Post by rayjcar »

If you refer to page 21 of the schematics in the link you posted, the keyboards and stops are wired as an 8x8 matrix, and the pedal board as an 8 x 4. These are connectors 2 through 5.
The Midi Boutique hwce2 encoder has 4 IDC16 input connectors. You would have to check with Midi Boutique to see if the Johannus connectors are physically compatible, and that the wiring sequence is correct. If not, you just need to use a bo16x4 breakout board to take the wires going to your plugs, chop them off, and insert them into the screw terminals.

The wiring of the analog inputs from the swell shoes may be more fiddly. They go to a 12 pin connector. The hwce2 uses an 8 pin header, for which you will need the matching connector.

I've never used their products, so I don't know if the encoder comes with default programming, or if you need to use the Windows app to so do.

Ray
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IainStinson
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Joined: Tue Dec 29, 2009 6:08 pm

Re: Johannus Opus 1200 conversion

Post by IainStinson »

Some years ago (12+?!) I converted an ancient 2 manual and pedal Johannus OPUS into a midi console. The electronics did not work really and were very heavy - I removed these.

I rewired the keyboards and used a Midi Boutique hwce kit (earlier version of the hwce2) for common busbar switched keyboards. The rewiring was tedious but the result worked well. The Johannus expression pedal operated "shades" over a light sensitive resistor which I was able to connect directly to the MB board (analogue input). I used one of the four switched inputs for the stops. The stops did not have lamps and did not have solenoids to operate them (using the pistons did not show on the physical console as there was no hardware to support this).

I've more recently used another MB board to convert my Phoenix console pistons to provide notes on / notes off switching. I build a passive little board to convert the Phoenix midi piston output plug into appropriate input for MB board.

The MB boards seem to he of good quality.

Good luck.

Iain
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