Hi zvir,
The EKO Tiger appears to be a 4 octave keyboard, not 5.
EKO Tiger Photo
This makes sense, looking at the circuit board, as there are only 3 divider circuits.
I once had an old keyboard that had an LC-tuned oscillator (like the EKO) for EVERY key. Due to its age, most of the oscillators had drifted out of tune. Some I managed to re-tune, but the rest were too far out. I ended up scrapping it, as the effort to rebuild was way more than it was worth.
The biggest problem was the variable inductor - the dust-core adjuster had the annoying tendency of breaking up - best to try replacing the tuning capacitor instead. If these had RC oscillators, then tuning would be a no brainer
The EKO Tiger appears to be a 4 octave keyboard, not 5.
EKO Tiger Photo
This makes sense, looking at the circuit board, as there are only 3 divider circuits.
I once had an old keyboard that had an LC-tuned oscillator (like the EKO) for EVERY key. Due to its age, most of the oscillators had drifted out of tune. Some I managed to re-tune, but the rest were too far out. I ended up scrapping it, as the effort to rebuild was way more than it was worth.
The biggest problem was the variable inductor - the dust-core adjuster had the annoying tendency of breaking up - best to try replacing the tuning capacitor instead. If these had RC oscillators, then tuning would be a no brainer
It is true what you said there, beelzebub. Tiger IS a four octave keyboard. However, there is an additional potentiometer that controls the amount of bass in the output. The first 20 (I think) keys are wired to two connection points, where one point controls "normal" tone, and the other controls the bass support. Which actually makes every oscillator a six octaver.
If it is not a very big problem for you, could you make a schematic of this oscillator? It would be of a great assistance in my attempts to repair my Tiger. I can provide extra information if needed.
If it is not a very big problem for you, could you make a schematic of this oscillator? It would be of a great assistance in my attempts to repair my Tiger. I can provide extra information if needed.
Hi zvir,
Unfortunately, I don't have any schematics. There are companies on the web that sell circuit diagrams (and service manuals), you could try them perhaps.
You could try an Electronic Organ repair shop, they may be able to help you with the circuit, and maybe even repair it for you!
Also, you could try reverse-engineering the circuits (reconstruct the circuit from the way the components are connected on the PCB) and then see if you can do anything from that.
Good luck!
Unfortunately, I don't have any schematics. There are companies on the web that sell circuit diagrams (and service manuals), you could try them perhaps.
You could try an Electronic Organ repair shop, they may be able to help you with the circuit, and maybe even repair it for you!
Also, you could try reverse-engineering the circuits (reconstruct the circuit from the way the components are connected on the PCB) and then see if you can do anything from that.
Good luck!
"back in the day" the way to build a keyboard was to use a "top octave generator" which was a crystal controlled oscillator and a series of dividers that gave you square wave outputs for the top octave. the rest was simple, since the rest of the octaves were derived from flipflops. the signal switching was done by microswitches under the keys, and various tones were achieved through filtering and mixing. the best part was, the thing was always in tune, and fine tuning for the master oscillator required only 1 adjustment.
Here are the plans and circuit descriptions for the PAIA Gnome synth from the mid 70's,and also the 2720 synth.
http://www.paia.com/manuals/docs/GNOME-howto-article.PDF
http://www.paia.com/manuals/docs/2720-buildamodular-article.pdf
http://www.paia.com/manuals/docs/GNOME-howto-article.PDF
http://www.paia.com/manuals/docs/2720-buildamodular-article.pdf
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