Sunday, April 1, 2012

TX81Z, K5000S

Been programming the TX81Z a bit. About a dozen patches or so, very surprising sounds. So I'll probably share a demo this week.

FM synthesis has really got my digital mojo going lately, such that I picked up a Kawai K5000S in dire need of restoration. The K5000S is known for sounds using more pure Additive Synthesis methods. It is also capable of some nice choir sounds and has a superb multi-stage bandpass formant filter for doing just that! Known functional issues of my instrument:
- cracked LCD (queue the Ladytron music)
- previous owners spilled red bull or something on it resulting in multiple sticking buttons with goo inside them.
So I'm disassembling the entire unit, pulling the cards w/ button switches, meticulously cleaning the PCBs of sticky goo, and removing/cleaning/replacing the small momentary switches. I ordered a new LCD that should be here later this week, it's going to look spiffy gray graphics on a white CCFL backlight...can't wait to see how that all goes.
K5000S_01
K5000S_2

9 comments:

  1. Hi! I have a K5000S with some dead buttons around the LCD. Any ideas how I should start addressing the problem? Disassembly should not be too difficult, but any ideas what to do after that? What did you use for cleaning? Did it help? Did you replace the switches?

    - Ilkka H

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    1. The tactile switches can be sprayed with Deoxit, or equivalent product, and tap the switch until the tactile leads show continuity on a DVM. Stubborn switches can be removed and soaked in deoxit. On my unit previous owners probably dropped something on the LCD which also cracked the surrounding button PCBs. So be sure there aren't any hairline fractures, test continuity of the traces with the DVM, and repair any broken traces if necessary. Good luck!

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  2. Thanks! Sounds fairly straightforward.

    -Ilkka H

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  3. It was fairly straightforward until I messed something up tonight! I got the boards off from the unit, and cleaned the tactile switches around the display. Worked fine. I started putting everything back together, and when I screwed the display and the buttons back, I decided to test if the buttons make contact with the switches underneath. I tirned the power on, and everyting worked fine until one of the switches under the display killed the whole thing! Display died in an instant, and Kawai does not come back to life anymore :(. Fuse is ok, all the cables are there, when I switch the thing on, I hear pop on the phones output as usual, nothing else. More work for me, I guess.

    - Ilkka H

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  4. There seems to be a hairline crack on the board hosting the switches. Dunno, might have been there all the time, or it might be that I caused it. Well, at least there is a place to start looking.

    - Ilkka H

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  5. Still wondering... the crack in the board with the switches should not affect the synth itself? So the defective part is related to the main board or power supply? Should the main board boot up without display and button boards attached?

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    Replies
    1. If there was a crack in the switch PCB, the functionality of the buttons would be interrupted but would generally not affect the display or boot-up. Seems the display has a problem that is affecting the boot-up routines causing auto shut-down. Fixing the display issue and the synth should be back to normal. Check display connection cables are seated fully. -g

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  6. Yes, it might be the display, too. I have to check the display connection very carefully. However, I've understood that the display should work without the backlight power connection (the small white cable).

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  7. Well, it might be the display, but it is not the connections. Damn.

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