Making a pedal box interface for the Wersi Comet

I play the song "Emotion" (B. and R. Gibb) at 3:38 with pedal bass.
After finding the 'secret' behind the internal communication in the Wersi Comet organ I decided to conclude my repair work by making a pedal interface so I can use a set of bass pedals and not having to rely on the automatic bass.
Apart from 'Emotion' I also abuse the song 'To the top' that I managed to make even more obnoxious than the original by Peter Andre from 1994.
I use these instruments:
Bass: Roland D-20
Chords: Siel DK-80
Rhythm: BOSS DR-202
Melody: Roland JX-8P

[@lugerocovers9449]

Interesting stuff to see haw organs work. Good work. 🎹👏👏

[@BadChizzle]

Wonderful

[@marcbrasse747]

Excellent. It’s almost as if you know what you are doing. 😉 My tip. Put it in a little box which you can then lay on the top of the pedalboard. Ouch, includes doing some extra soldering. 😁

[@T-Cat-wy7ly]

You are a wizard!!! The main problem of the Comet Organ is the very sensitive keyboard-scanner IC. Its made in C-MOS technology and loves to die at unexpected moments. A little bit static electricity at the wrong place and one of the keyboards is dead. The concerning Siemens SM 304 is obsolete since decades - and you have invented a solution for this long lasting problem. Actually this Siemens Chipset is used in many Instruments of the early 80s because with this IC's you can get rid of the old analog square to sinus / sawtooth conversion and the octave mixing. This used to take a squaremeter of circuitboard, kilometers of cable and hundreds of contacts at the keybeds. When I watched your first video about the Comet I thought "Good luck and rest in peace - this will never work again" - and now ... its working fine! I'm curious what you figure out about the "Magic Fingers" extention - it is a Sequencer, a arpeggiator and a Melody On Cord system. I never seen a "Magic FIngers" working - so carry on cowboy 😉.

[@organfairy]

What you say about about the sensitivity of the WIC3040 / SM304 corresponds with what I have seen: Sometimes the upper manual freaks out like if there suddenly was a lot of keys pressed at the same time. I have a suspicion that the input impedance of the IC is too high so it picks up some noise - and with a lot of oscillators and four big buck converters in the power supply that pours out all kinds of electrical noises there are a lot that can go wrong. It could also be a bad connection or maybe the IC is on the verge of kicking the silicon bucket. Working fine..... there is still the problem with the VCF, and the snaredrum changes its sound when the organ has warmed up, but apart from that it is working reasonably well. I have recorded a collection of music with it lately in multitrack so I have gained some experience with this rather strange organ. (If it was a TV-shop album it would say something like "featuring music by such memorable artist as Eagles, Whitney Houston, Gotye, Eurythmics, and many more, all in stereo on the fabulous Wersi organ") There will be some videos later.

[@organfairy]

To my great surprise I - well, Google - actually found the user manual for the Magic Fingers. Based on what it said I should do, I can conclude that my Magic Fingers are broken. I do intend to try and get it working again but the Wizard Cowboy needs to get a little away from the Comet in the coming weeks :-)

[@organfairy]

Good news: I figured out what was wrong with the Magic Fingers module. I was about to give up when I noticed a tiny wire that was hanging a couple of millimeters outside the plug on the back side of the circuit board. It had simply become unattached for some reason. It seems to be working now.

[@T-Cat-wy7ly]

​@@organfairy I understand you very well! Sometimes need some distance from 'difficult' instruments too - otherwise there will be deaths. My Wersi Galaxy is sitting in the corner since nearly two years. It refuses to work because of a short circuit in one of the modules - and there are around 50 of them..... Same with a Böhm Silverbird - I ignored the instrument for 18 month because the bass pedal refused to work. Last week I started to work on it again and hooray - I found the error. Due to an error during assembly, the MIDI bass pedal sent on the wrong channel.

[@nicole_local]

With the pedalboard protocol successfully reverse-engineered, how hard would it be to attach a larger set of pedals?

[@organfairy]

Theoretically it can support a five octave pedalboard. However, when you get above the lowest two octaves it sounds somewhat thin and when you get higher up it sounds like a banjo on helium - as I claimed in the video. The reason is that the filter system is static - it uses the same filter parameters for all the notes and since the filters are low-pass the notes will get gradually weaker as you go up in frequency. Another thing is that the bass voice card is monophonic so you can only use one pedal at a time. If my pedal interface should be converted to more pedals it will need to have more 4021 shift registers - one for each eight notes and the clock delay circuit should be modified so it activates the clock earlier than number 48 as it does now. If I should add another octave it should kick in at 36. I haven't researched this yet but there is an input next to the pedal input marked "keyboards" and I have read that this could be use if you wanted to add more keyboards to the organ or separate keyboards that other people could play standing next to the organ. I suppose the system is identical to the pedal interface except that it can play polyphonic using the piano and solo voices.

[@T-Cat-wy7ly]

​@@organfairy Referring to the Assembly Instruction of the Comet Organ (page 61ff) here the description of the additional Keyboards "Satellite" The Comet can be extended with four external Keyboards called "Satelite" - these four keyboards can be mapped to four soundgroups "Solo - Ensemble", "Piano", "Bass" and "Guitar". The soundgroups can be played by the external "Satellite" but is controlled by the organ. Electrical the keyboards are connected as a chain. In deed the keyboards contain the same keyboard-scanner then the lower keyboard. In addition there is a controlpanel with six buttons. Two of them are for Octave up/down. I think the remaining four are to assign a soundgroup to the "Satellite"

[@organfairy]

You are probably right about the buttons. I took a look at the schematics and there are four connections from the 'keyboard' plug marked PX1 (bass voice card), Piano, Gitarre, and PHK (solo voice card). Bass, solo, and piano are connected as a logic OR which means that both the organ and the satelite keyboards can play them at the same time. Guitar has a selector button on the organ that needs to be pressed before the guitar can be controlled externally (if I understand the circuit correctly) which is probably because the guitar is monofonic so whoever plays the highest note will take priority over the other if both were connected, and since it is a German organ such anarchi could not be allowed :-)