Ahlborn C33 tube organ - new life

[Rato]

Hi everyone. This is my first post on this forum. I have studying forum and ucapps.net for three years. Sorry for my bad english in some cases.
 
I got an old organ "Ahlborn C33" made around 1960's. There are two manuals and pedal (and 33 stops). The instrument is functioning, but it was in very poor condition. Many of the keys did not work, some stops were not working, and the amplifier and speakers were outside the organ, because there was no room inside. The organ had about 200 ECC82 (12AU7) tubes and associated electronics that served as oscillators.

Here are a few pictures of what they look like:

I don't have old picture of mine working, but this is the same organ (without speaker boxes).



I decided to remove all the old electronics because it was not possible to repair. Not only are the parts were unavailable and expensive, but the sound was not anything special.



From the organ I use almost everything except tubes, resistors and capacitors. Many keys were damaged and needed to be glued or otherwise repaired. Each button has about a 10-15 contacts. I have removed the old cables and for each key merged only one wire. I soldered a wire to multiple contacts for a better grip (old 56K resistors are not connected). After that I again put mechanisms in their old place. Here's the picture:
 

 
Also I made a fixes to pedal, but there was more work to do, because some mechanisms were literally broken.
 


Then I ordered a printed circuit board and made connections to DIN, DOUT and CORE. I used two CORE printed circuit boards because there were more than 128 DIN.
 


I have plenty of space in organ so I installed an old ATX case and motherboard ASUS P5PL2 (with CPU Celeron D 2,6 and 3,5 GB of DDR2 RAM). All this is powered by ZALMANN quality silent power supply (400W) that powers the PC and MidiBox (5V for logic and 12V for the foot-light). I installed the 60 GB SSD hard drive due to its speed and silence.




PIC Midi printed circuit boards are connected to the Game Port. This motherboard have gameport header. It works great and proved to be the best solution for my case. Because Windows 7 and 8 can't support the old Game Port, I installed Ubuntu 14.04. The sound card is the integrated, and if need be, we can also think of a better (PCI or USB). Audio amplifier and speakers (2x12" 4 ohm) are mounted into organ.
 
Speed:
- computer turns on and loads Burea church samples in GrandOrgue in 1 minute and 5 seconds.
- computer turns off in three seconds.

Instead of the old registers that can be used for other (smaller) organ, I put aluminum panels with buttons and LEDs. I have not installed the panels on board yet. Later I will add labels. Sorry for plenty of wires :-)) .
 

 

 

I'm sorry also for some bad photos.

 

Now - one problem.

I have two foot pedals (for great and swell manual). How to connect them to the "mbhp core"?
On each of them I put linear potentiometers of 5 kilohms. The center of each potentiometer (taper) I connected with short cable to the analog input on the "core". The ends of each potentiometer I connected to 5VDC and GND respectively.
However in "MIOS Studio" nothing happens when I move a foot pedal, there are no "MIDI events". All other controls are working properly.

What could be the problem? Is there anything further to do to get a foot pedal operated with the application MIDIO128?

[PetrusAscanus]

Hi have the schematics of that organ....

If you want I can scan them

[Psykhaze]

Original photos seems to be dead links. I wish i could see these.
Bests,
JK

[PetrusAscanus]

I can not uplad the file, so here is a dropbox link:

https://www.dropbox.com/s/cehrg451lpcnhjv/Ahlborn.pdf?dl=0

Ahlborn C33

I had these papers from Ahlborn Ditzingen.

The organ was made around 1960. It plays very well and has been used the last decades for organ studies.

I think it will become available because it takes a lot of needed place.Ahlborn.pdf