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Unlocking the Yamaha E70

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  • Hello Ewaves, it seems that this thread has been abandoned for a long time, could you check with the E50 what I say? I really don't know if the E50 can pass the "lower" sound to the keyboard above. I don't know what the main differences are with the E70. Greetings.


    • Technically the are the same, but E50 have not everything populated, I have no coupler switch to put the lower to the upper keyboard, but I am pretty sure they must sound independently to the presets.
      Its an old organ, first thing to do is to check the Voltage's and state of the power supply and give the switches, sliders and connectors a nice cleanup with some cleaning spray, and check if the digital cards are firmly fixed in there slots.
      Maybe it will solve your problems...
      Last edited by Ewaves; 08-31-2020, 09:16 AM.


      • Alejandro

        I forgot to mention, I think you now that the total polyphonic for lower and upper orchestral keys is 11, with a max. of 7 for each keyboard.
        But if you couple the lower to upper, then you have 2 voices for a key, so polyphonic will be half, so after playing key 1 to 5 the notes from key 6 and 7 sounds with only 1 voice/preset, and maybe upper presets have highest priority.
        Also playing presets with fast decay for lower, voices will be stolen by upper presets if you play more than 5 notes at a time, I think, can not confirm this by having no coupler.


        • Hi Ewaves,
          Thank you for your comments.
          I already knew about polyphony, but this has nothing to do with it.
          I have also noticed that if I am playing a chord in "Lower" with the bass in "Fingered" mode, sometimes when playing certain notes on the "Upper" keyboard the note that the bass gives varies, it is as if they were communicated from somehow "Upper" and "Lower". I will start by restoring the power supply, and when I make the modifications I will draw more conclusions.

          ​Thank you.


          • Its a good Idea to check the PS / switch cleaning anyhow, but when reading this,

            I have also noticed that if I am playing a chord in "Lower" with the bass in "Fingered" mode, sometimes when playing certain notes on the "Upper" keyboard the note that the bass gives varies, it is as if they were communicated from somehow "Upper" and "Lower".
            I notice that other people in this thread have complained about the behavior of the keyboard.
            When looking at the schematic of the later "modern version" of this organ, the E75, they used a different key-scanner chip, but with the same key-matrix and the same scan-speed and voltage.
            They put over the note-scanning lines a capacitor of 560 pF (13 pieces) and the other scan-lines 1800 pF (12 pieces) to ground, with the purpose to create a small buffer and prevent key-debouching, that's another thing to look at.
            Last edited by Ewaves; 09-07-2020, 05:34 AM.


            • I placed my post a bit to fasts without making a clear point, well, maybe I write to fast, to technical and Its not my native Language.😁

              In the above post I conclude that the keyboard-contacts makes a intermittent contact ( bouncing ), and in a digital system, where the keys are forming a big digital "word", they lead to unexpected results like the "lower" keyboard became "upper".
              A good cleanup of the key-contacts will do a good job to mostly prevent this.
              However, by the smallest pollution it will do it again, it also depend of the quality of the switch.
              In the later organ series Yamaha put some capacitors on there scanning lines, so the response of the keyboard will be a little less, not noticeable, but will give a stable result of a key pressure.
              In modern systems they solve that in software to program a small delay after a key pressure before they reading the key value.
              However, there are no cpu's in these organs, only pure logic, so they solve it with some hardware....
              Last edited by Ewaves; 09-09-2020, 09:25 AM.


              • Hello Ewaves,

                I see that you are a true expert on the subject. Everything you tell me has a lot of logic, in this way I realize why there are certain components in the circuit ...

                I would like to ask you some questions:

                ​​You think there would be any possibility of adding polyphonic sensitivity?

                Could some tension coming from a keyboard be sent to the different voices through a circuit that divides the signals and coordinates them with the different voices?

                Could these voltages reach Vcf and Vca, in parallel with some other voltage that their Parameters vary?

                Thank you very much for continuing with this thread !!!


                • Hello Alejandro

                  No, I am not an expert, I am a hobbyist, I now some basic things.

                  All the things your mention are possible, but the sensitivity must came from an external MIDI keyboard, because the original one's have only a single row of key contacts.
                  It also depends of all the effort you want to put to the organ, it will be a lot because of making a lot of level shifter's to access the negative logic.

                  There is already a circuit inside who routed the key voltage to the different VCF and VCA's, key voltage circuit deliver the gate signal and so we can varying the speed and voltage depth of the individual EG's for loudness or filter sweeps, but we have to do that true MIDI and the hard thing will be to synchronized it with the system, because of the tight timing of the circuit.
                  But it will be relative easy to make some common LFO's for all the filters and VCA's, put some noise to it, a ring modulator and so on.

                  The way I want to go is to make MIDI for it, and to check how good the waveforms are looking, and how good the filterschip's are tracking the keyboard, compared to the filterchip's from the CS series, it must not have some "toy-like" spec's.

                  But first I have to examine the key scanning protocol, to see if I can realize what I'm planning to do, make some easy level shifter's, and dive into the Arduino stuff.


                  • Hello Ewaves,

                    I would love for you to have sensitivity, of course it will be with another keyboard, or via MIDI.
                    If there is any possibility of routing the tension that comes out of the circuit of the keys to the different voices, I want to carry it out.
                    If you have the same intention and want to share your knowledge, "I am all ears".
                    If I can help to advance something?

                    I think you can get good sounds from these organs, considering that next to the "CS" they sound like plastic compared to metal and glass. But they sure have many advantages.

                    Did someone from this forum finally install the arduino?

                    Greetings and thank you.


                    • There will be a lot possible, but It depend on how hard it will be to place MIDI and do the Arduino stuff, and to manage that tight timing process from the logic chips.
                      And if the sensitivity will work, then we have to make some hardware to let it do its job, even polyphonic aftertouch will be possible.
                      But first thing first, I have to look if it al will work.

                      Just saw your Y.T. vid. Brass Ribbon, great !! How did you do that with the ribbon ?

                      Yes, the organ have some great sounds and potential, but there are some things that are disturbing me.

                      First, the total polyphonic of 12 instead of 15, but I can understand that, possibly they are limited by the use of the fixed logic, or the digital sound generation will be overloaded if they push it to 15. Today no one will make 15 "synth engine's" and used only 12 at the time.

                      Second, why they made the ( less advanced ?) VCF-chips for this organ instead of the one's used in the CS series ? They used already the same VCA's.
                      Why they give the pedals no keyboard tracking, they make place for that on the PCB already but not used it ?
                      Why they did not placed some buffers after the sample and hold capacitors ?
                      It look a bit If they want to go for the cheap, instead it was an very expensive organ, or is there a technical reason for it ?
                      I will try to find out why.
                      Don't understand me wrong, the design of the organ electronic is a true masterpiece.

                      And as far as I know, no one did something with an arduino in it.
                      Last edited by Ewaves; 09-12-2020, 07:08 AM.


                      • Hello Ewaves,
                        I do not control some technical things you mention, but I try to get used to the idea,

                        The "Ribbon" is simply a sliding potentiometer connected to the expression input of the PCM81, the rest of the work is done by one of your programs. I also did tests by connecting it to the pith bend wheel of a MIDI keyboard and sending a signal to various multi-effects. What I do is vary the pitch in the audio.

                        I have seen in some Yamaha organ a sensitivity sensor with which perhaps a paraphonic sensitivity could be achieved, it must be a device that captures the force with which the keys are struck, and depending on the force it will release more or less tension .


                        - Alejandro.


                        • Hello Alejandro

                          I' m not aware that software can control the pitch of audio, great !

                          Yes, that's the way these g-force sensors work, but they are mostly interfaced with a digital output, you have to translate it to something analog..

                          Greetings, André


                          • Hello, does anyone have a Yamaha Electone E-70? Greetings to all!


                            • Hi Evawes, how's the E-50 going, have you made any progress? Greetings.


                              • I will start soon with it, but first I have to look at the state of the organ, on the moment some presets are not working good, and the lower manual keys are not reacting on the octave switch, the keyboard is fixed at 4. (one octave up )