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Topic: Roland RD150...Anyone Have This Problem?

  1. #1

    Roland RD150...Anyone Have This Problem?

    Geez, el junko. I liked this weighted keyboard alright but have only had it a year in my home studio and now there are two keys that even though you barely touch them, put out velocities of about 120. Drag. Anyone see this happen on this or other models, this early in the game? Can't imagine lugging this thing in for repair. But at this point I'm using SELECT NOTES, then CHANGE VELOCITY on every part. Talk about a pain.

    "Computers in the future may weigh no more than 1.5 tons." --Popular Mechanics, forecasting the relentless march of science, 1949

  2. #2

    Lightbulb Re: Roland RD150...Anyone Have This Problem?

    Hi Tom,

    I had a similar problem with one key on my RD-700 when it came brand new right out of the box.

    I spoke to someone at a Roland Service Center who explained me how to fix it, without having to send it in and having to waiting for several weeks.

    1) You have to remove the cover, internally unplug the keyboard (ribbon connector if I remember) and remove the entire keyboard to gain access to the contacts beneith the keys! I don't remember the exact details for this, but if you're used to opening up equipment it will show itself.

    2) Then find the affected keys and carefully remove the gray rubber strip that covers their position.

    There can be several causes for the problem, but performing the following, possibly redundant actions, worked for me:

    3) Clean the brownish contacts on the printboard corresponding to the keys' location using a cloth dipped in some ethanol or isopropanol (audiocassette head cleaner).

    4) Also clean the black contacts on the rubber strip.

    5) Wiggle and stretch the rubber strip at the position of the affected keys to get rid of possible 'deviations' in the strip. It doesn't tear that easily so it's relatively safe to have a serious go at it.

    6) Reassemble the rubber strip taking care that the small rubber extrusions are completely pushed in the corresponding holes on the printboard (using the back of a nail or something).

    7) Reassemble the entire keyboard, hoping that you don't end up with some leftover screws

    If you dare to take this 'risk' and it still doesn't work, I'm afraid that you have to send it in for repairs. The Service Center guy sort of reassured me that if I opened up the unit myself, I would not lose (future) warranty, unless I broke something of course.

    Let me know if it worked out for you.....


  3. #3

    Re: Roland RD150...Anyone Have This Problem?

    I hate the Roland switches. Basically it's fingers of high carbon paint on the PC board. A flexible "rubber" piece contains a conductive slug that gets pushed down by the key and shorts the fingers together.

    There are two switches per key, mechanically displaced in the vertical axis. Velocity is determined by difference in time between the two switch closures.

    If the second switch is shorted then computer doing the timing sees the time difference as 0 so it puts out max velocity. If the carbon gets worn off or a contaminant like skin oil gets in the way, the note goes dead.

    Generally, if a note goes dead it's because the carbon is worn away. First wipe the slug and pc board with a dry Q-tip. Then get out a soft pencil and lay down some carbon. Some people have had success with conductive paint. Easiest place to get that is the automotive store as a window defroster/imbedded radio antenna repair kit.

    I mention the above because it's generally the easier repair. I have yet to figure out a definitive long term repair for shorts.

    Shorts can come from small pieces of conductive paint bridging the fingers. Generally a dry Q-tip will clean them out so that's where I start. You have to get access to the keyboard and remove the pc board containing the contacts. If you are careful, you can insulate any conductive chassis surfaces with plastic or newspaper and actually turn on the keyboard for testing. This is important because the switches are very picky. The layout of the two switches is pretty obvious. Practice bringing a finger or a flat ended object down evenly and getting various velocities.

    You can generally run a Q-tip under the flexible rubber part. If you have to remove it, be very careful. The flexible piece is generally held in with little teets. The PC board material is hard enough and hole edges sharp enough to cut them if you are not careful. It's very important for the flexible piece to lay perfectly flat on the keyboard if you want even velocities.

    If a dry Q-tip doesn't work then you may want to go to alcohol. I generally try to avoid it. This kind of switch is not like a gold contact, i.e., it doesn't go from .1 ohm to infinity. The on resistance can be in the hundreds of ohms so it's more like an analog circuit. Obviously you don't want to remove the carbon with the solvent.

    After you put the flexible rubber part back, use your finger/object to make sure there is a basic velocity matchup with the keys next to it.

    Like I said, I have not found a definitive answer to this problem. I've repaired my PC88 several times. It'll work for several months and then get stupid on me again.

    Hope this helps, I need to work on my PC88 again. If figure any more out I'll post it.

    Good luck.


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