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Electone EL 90, MDR unit not working

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  • Electone EL 90, MDR unit not working

    Hello all,

    I have an EL 90, where i replaced the floppy disc drive with a multi image "Flexidrive", using a SD memory chip. Excellent solution, where I have all of registrations, files etc on single SD card. (If you are interested, let me know and I would be more than happy to send documentation and some photos.) This worked very well for some 2-3 years. At one occasion i was hearing scratching in the speakers, so I did restart the organ, but the MDR unit did not lit up. Had an electronics technician home for half a day, but we did not localise the cause of the problem. I ordered a new PCB, the one sitting right under the MDR panel, 6 weeks waiting 160EUR cost and problem is still there. I drove the instrument to, to my understanding the only Yamaha approved repair shop, but the result is: still not working.New electrolytic capacitors on the main power unit PCB changed, right level of current everywhere, so the engineer thinks, that it is problem in data transfer somewhere between the main board and the PCB sitting right under the Floppy drive. Problem description sent sent via Yamaha Europe to Japan some 8 weeks ago and until now, not even a reply.

    So my questions would be:
    1. Have anybody of you experienced similar problem and found solution?
    2. Would anybody know of an EL 90 where the two PCB:s mentioned here above could be taken? Or alternatively are there any spares on stock anywhere?

    Reason chasing used parts is, that these parts as new must be ordered from Yamaha in Japan and because of the age of the instrument, not ex stock, but must be produced as single items, another 6-8 weeks delivery time and cost 4-5 times of the current value of the instrument (sound and working).

    Thank you for reading and appreciate your event. experience.


  • #2
    'not lit up' suggests your floppy emulator is not getting power...
    (That is if you are referring to the emulator, and not the led indicators on the organ panel)
    Do the Electone panel LED's function, and track number indicator ?

    Have you measured the 5v actually at the floppy emulator?
    The 5v supply on the power supply / power amplifier (PA Board) is routed to the floppy via connectors on the Analogue (ANG) pcb.
    I have seen EL90s where the joints of these connectors to the pcbs have failed and needed to be re-soldered.
    I have also seen on some organs this supply routed via the MIDI connector pcb. I'd check the joints there too if this is the case on yours.
    Do you still have a physical floppy drive. If you plug in the power connector to a floppy you should get rotation of the disk on insertion regardless of any data transfer issues.
    I'd start with this simple stuff.
    I have a spare working MDR pcb (In UK) , but you have already replaced this ?


    • #3
      Hello Ian,
      first of all, thank you for your reply. Let me expand on the problem. The disc emulator is working well, as far you can judge, it has normal behaviour in it's display, e.g. scrolling between the file images and reading them in. The problem indication is, that the LED:s on the MDR panel remain black and the organ does not react to pressed MDR panel buttons and the content of the registration files does not get transferred to the organ. When I run the C# test sequence, all LED's, incl. the MDR panel ones work, passing the test. The engineer at the Yamaha repair shop tried also the function of the FDD, which I have and know, that it's OK.
      Yes, I have now two of working MDR pcb's, so next candidate to test would be the pcb sitting right under the Floppy drive / emulator (sorry not being able to give you better description, since i left the technical manual with the repair shop.

      I can also tell, that the indication I had firstly was smell few moments after starting the organ, which showed later the problem of leacking electrolytic caps, which got repaired and the capacitors are replaced by new ones. The cause of the overheating on the PA board was the capacitor, which have the function to hold tha last registration, also this component is replaced by new one (Yamaha original part).

      I hope, that this description could narrow down the problem area and would appreciate very much to hear your opinion about it.

      Greetings from Sweden



      • #4
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        • #5
          Hi lan,
          Would you see following approach as possibly good way to target?
          1 Assuming My FDD eliminator works correctly
          2 i have right voltage on the components involved
          3 and either the motherboard or theMDR board are faulty.
          If You would be willing to sell yout MDRPCB to me and this would start the organ, this could make the repair attractive.the reason being the new price of the MDR pcb being per Yamaha offer in the vicinity of250 EUR and the motherboard ranging to approx. 1000 EUR. Since they have to be produced against order.
          In other case I would probably have to scrap my el 90 and get me somewhat newer organ, like el 900m.
          If you consider this scenario as reasonable, would you be prepared to sell the board you have?


          • #6
            Yes, sounds reasonable with the addition of 4. Possibly connection between DM and MDR boards. Reseat the connectors perhaps, check continuity (remote possibility perhaps)

            Yes I can post the board to you.
            How about send me the cost of postage by paypal (around 20 Euros I think) then test it to see if it solves your problem. If it works, great, then maybe send me a small donation, otherwise could you return it to me please.
            Let me have your address in PM.
            I'm actually away from home for a couple of days but can attend to it on my return.

            To be clear, this is the pcb which attaches to the same 'top-hat' metalwork that the fdd also fixes to?

            Also, is your MDR board the original one fitted to the organ ?
            You may be aware that Yamaha numbered the ribbon cable 34-1, compared to more standard 1-34, and used a floppy that conformed more to Shugart standard than PC. I understand that when people have requested replacement FDD from Yamaha, they have been provided with a complete MDR board plus floppy. The MDR board being a modified version which interfaces directly with PC type floppy drive. (Guessing maybe the same as in later ELx00 range of organs which do use the more standard PC type of drive ).

            The earliest reference I found on this issue can be found here https://tonnemansblog.wordpress.com/...a-yamaha-el90/

            My board is the original type with the 'back to front' ribbon cable, though maybe your emulator is configurable to work with either pc or Shugart interfaces. You may need slightly longer ribbon cable.

            I think that covers everything



            • #7
              Hello Ian,
              It is very difficult to express how happy I was receiving your answer today and the generous offer in it. And the knowledge cumulated in the organ forums and prepares to help each other, amazing!
              Thank you very much also for taking part in my endeavour to bring my EL 90 back to life.
              And yes, I am aware of the differences in the FDD configurations, have Binder full of documentation on this subject. I purchased couple of the USB emulators being offered on e Bay, but they were not of the right type, the hustle with conversion of the files made me to give it up and contact company Flexidrive in Germany. The fellow there was extremely helpful, so the solution I have now is advanced emulator in my case working with SD memory cards, formatted by a program underneath r any windows version, called Winimage, which produces .ima files. Then using explorer you just move the files to the SD cards, plug it into the emulator scroll to what you need, push the MDR play button and you are set. The front panel has also female mini USB contact, which can be configured to be used with small touch screen for easier operation. So anyway this is an industrial piece of equipment developed to use with older robots - Swedish ASEA- which can be easily configured to whatever. Is needed by a configured file which can be easily loaded by the memory media.
              Here the link:
              https://www.floppyemulator.com/ if you look at their page, you will see it mounted in my organ. But unless they do not have the configured ready, it is question of a day, provided they get reference to the FDD used. It is not cheap, but works perfectly.
              I will send you PM with my coordinates right away and we take it from there.
              And once again, many thanks for your support


              • #8

                Thanks to Paradox friendly assistance my problem got resolved. After few month of waiting for replay from Yamaha (still not arrived), I really understood the importance of this forum in keeping aging instruments working.

                The problem was faulty MDR pcb. After replacing it and updating firmware and config file in my FlexiDrive emulator, the organ works perfectly again.
                Looking for solution of my MDR problem, I was reading about the problem of leaking electrolytic capacitors, so I had them replaced as a matter of problem prevention.