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Keyboard PCB repair + taking the funk out?

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  • Keyboard PCB repair + taking the funk out?

    I found on the street, a Technics sx-e44 electric organ, it has two major problems. The first one is very hard to google for it would seem.

    1. Stuck note

    The upper set of keys (I'm not really an organ person so I don't know the technical term for the different sets of keys) has a stuck note. The keys themselves are all fine and feel great, but there is an A# note that just won't stop. I partially dismantled the device, got access to the rubber buttons, lifted up the affected button and swabbed the contact with alcohol, but it did not resolve my issue. I'm having a hard time googling for potential solutions because I keep finding either the opposite issue (no contact is made) or mechnical issues (the key itself isn't mobile or stuck or something). I was never able to find a service manual for the e44 but I did fine one for the e33 and lo and behold, the only thing it doesn't have a part number for is the keyboard pcb itself (I will say though, I'm thoroughly impressed with the level of detail for everything else. PCB layouts, circuit diagrams, full bill of materials for everything from the ICs and passive components to the screws and packing material, right to repair activists, take note!!).

    I haven't yet dismantled the device enough to get access to the PCB itself. This is a weekend thing. But I'm hoping I can find some more information specific to this problem and do some reading before I really dive into it.

    2. Funky musty smell

    This thing smells awful. Cleaning the PCBs is tedious but straightforward, but how would I clean the body? Cleaning the outside varnished wood I can do with a variety of cleaners, but I'm not sure how to clean the unvarnished bits of wood that are inside. This is inside my apartment and it is winter, so I'm hesitant to use any strong solvents.

    Bonus Question:

    Anyone aware of any project logs, youtube videos, or something else, where people have gone circuit bent these types of devices? Considering how well documented all the important PCBs (well, I would assume the keyboard PCB is important but I digress) and how easy they are to remove, I don't see why I shouldn't start wiring things up in strange ways. I mean, c'mon, how can this thing NOT have distortion, sheesh ;). Ultimately, if I can't defunkify the body then I will rip out the electronics. I mean the speakers sound great, there is a spring reverb in there, and it doesn't seem to be entirely PCM sounds, so I should have some fun with it if I can't restore it.

    Any advice would be greatly welcome,
    Thanks in advance

  • #2
    If the funky smell is due to the organ having been in a cigarette smoke environment, or in a damp place where mildew grew on the finish, or other obvious surface contamination, you might have some luck using an old-fashioned furniture cleaner/polish such as Pledge or Favor. I have used Murphy's Oil Soap on really mucked up finishes. Just don't use anything with alcohol in it, as that will totally ruin the finish. I also wouldn't use any strong general purpose household cleaner like Mr. Clean or Formula 409, as they might contain chemicals that would dull the finish, even though they would certainly cut through the gunk.

    As to the key that sounds continuously, are you sure it isn't just the rubber button? Did you try hooking the pc board back up to the ribbon cable with the contact strip removed? That would tell you for sure if the button is just sagging down, shorting out the conductive spots underneath it. You can move those strips around, as long as you keep them in the same orientation (front to back) and take note of the way the buttons are grouped relative to the spots on the board. If the trouble moves with the strip, then of course the strip is the problem.

    But it might be a flaw in the pc board itself, so you should inspect visually for a cut or shorted trace, check with a meter for a faulty diode. Also, test the organ with the pc board UNPLUGGED from the ribbon cable to see if the cipher is present without the pc board. if it is, then the trouble obviously is somewhere else, perhaps a scanner chip on the CPU board or some kind of console interface board, if used in that model.

    *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!


    • #3
      Thank you for your reply.

      Regarding the smell, I will use murphy's oil to thoroughly clean all the wood bits. I would use IPA and a tooth brush to clean the electronic bits. I sincerely hope it works because I'd love to keep the chassis intact. If I can't, I can't, the salvageable electronics alone are worth keeping and re purposing into something strange. But it does make a nice addition to my living room.

      As for the broken key, I have not had a chance yet to fully disassemble the device. Definitely not something to start on a weeknight. I will try this over the weekend. I did however, get as far as removing the key, lifting the rubber button, swabbing the contact with IPA, and even (and yes this is a bit dangerous) powering it on and lifting the button with pliers but nothing doing, the note just won't stop. So this weekend, I will fully take the device apart and get access to the PCB itself and take a look.

      When you say ribbon cable, I do want to make sure we're talking the same thing here. The keys in the keyboard work by depressing rubber buttons with a carbon ... puck? in them that makes contact with the PCB. So when you say ribbon cable, are you referring to the fact that the rubber buttons are in the form of a strip of rubber buttons?