• Posts
  • RSS
  • ◂◂RSS
  • Contact

  • Yamaha P85 Keyboard Hack

    July 15th, 2011
    hardware_hacking, keyboard, music  [html]
    My yamaha p85 keyboard has internal speakers and two headphone jacks. Plugging anything into either headphone jack turns off the internal speakers. I think the intended use is for a student and teacher to both be able to hear while not bothering anyone else. For my purposes, though, it can be annoying. If I'm playing and I don't have good (or any) monitors, I would often prefer to have the internal speakers remain on so I could hear myself better. Luckily, the internals are relatively simple and this behavior can be modified.

    I opened up the keyboard (instructions from the last time I did this) and found the board controlling the output jacks. It looks like this:

    The big solder bits are where the two jacks connect. There are six pins. From looking at the traces (sorry about the poor focus) I could see that the middle two were connected together and the top one is grounded. Testing with a multimeter set to resistance, the middle two pins were normally connected to the ground, but disconnected when a cable was inserted. Looking into the jack, I think maybe the end of the cable pushes apart two bits of metal to break a connection. If we could short circut this detection circut, so that it always read "connected" then the internal speakers would stay on.

    I considered short circuting both detection loops and then adding an externally accessible switch to disconnect them, but I decided against that because of the inconvenience of cutting a hole for the switch and mounting it. Instead I decided to modify only one of the jacks so that I would later be able to choose whether to leave the internal speakers on by plugging into one jack or the other. Some soldering later and we had:

    It worked exactly as I had hoped. I closed everything back up and made sure it worked before putting in all the screws. Then I painted the modified jack with some white-out. Total time: 3hr.

    Now to see how well the internal speakers do at a dance!

    Update 2012-05-29: This is working pretty well. You still want a monitor so you can hear yourself, but it's now loud enough that if you can't get a personal monitor with just you as a supplement to the overall monitor mix it's not that bad.

    Comment via: facebook

    Recent posts on blogs I like:

    Collections: Teaching Paradox, Europa Universalis IV, Part II: Red Queens

    This is the second part in a series (I) that examines the historical assumptions behind Paradox Interactive’s grand strategy computer game set in the early modern period, Europa Universalis IV (EU4). Last time, we took a look at how EU4 was a game fundame…

    via A Collection of Unmitigated Pedantry May 7, 2021

    Amtrak’s Continued Ignorance

    There was a congressional hearing about high-speed rail. Henry Miller in comments here took notes – thanks for this, much appreciated! The overall content was lacking; the politicians seemed like they were spinning their wheels, not because they themselve…

    via Pedestrian Observations May 7, 2021

    Books and websites on babies

    Several people I know are expecting a first baby soon, and I wrote up notes for one of them. Might as well share here too: Medical:Scott Alexander’s Biodeterminist’s Guide to Parenting is an interesting read, and some parts are actionable.  If you live in…

    via The whole sky April 14, 2021

    more     (via openring)


  • Posts
  • RSS
  • ◂◂RSS
  • Contact