Thursday, October 23, 2014

Electronics Mod: Ensoniq KS-32

A long, long time ago, I obtained a Midi Workstation, called an Ensoniq KS-32.  I'm still thankful for the great deal I got on it.  I'm also greatful that the guy I bought it from didn't break my leg, since I didn't finish paying that really good price for 3 years.  Despite some harrowing times (orange juice dumped into it), it still functions to this day.

One note about the KS-32, is that the settings are stored on-board in RAM, or Random Access Memory.  This not not the much better version, NVRAM, where NV stands for Non-Volatile.  This means, if there's no power to the memory, the settings are gone.  To prevent the settings from being gone every time the KS-32 is powered off, or unplugged, there is a 3-Volt battery onboard.  The battery is a fairly common CR2032.

There are three problems with this.

  1. The battery only lasts between 5 and 7 years.
  2. The battery is located inside the chassis (six screws, and an internal ribbon cable to deal with).
  3. The battery is soldered directly to the main computer board.
About 2 years ago, after having lost all of my settings, track presets and sequences, I opened it up, removed the old battery (with flat wire-cutters), and put in a new battery, soldered to some lead wires.  All good and well, I was able to save settings, and track presets, and everything was happy.

Then, last year, there was some major re-arranging of the room where I keep the keyboard, and I had to unplug it, and put it away (in its hard case, into the closet).  When the keyboard moved, happened, the battery moved around on its wires, and shorted itself out ... probably not for long (it still has a charge now), but for long enough that the keyboard lost all of its settings.

Well, when I set the keyboard up, and realized that it had lost its settings again (I have a SysEx backup this time), I decided I needed to do something smarter with the battery situation.  So I did some research on CR batteries, and decided to go bigger.

The Mod

Parts list
  1. CR2450 button battery
  2. 2450 button battery holder x2
  3. 3 x1.5 inch circuit board from radio shack
  4. Red and Black wire spools
  5. Electrical Tape
  6. Nuts and bolts (x4)
  7. Washers (x16)
  8. 3 x 2 inch piece of plexiglass.
  9. Thin cable tie
  1. Soldiering iron
  2. Dremel Tool
  3. Screwdrivers
  4. Pliers
  5. Wire cutters.
  6. Multi-Meter
I soldered the two button battery holders onto the circuit board (buy more than you need, they can break in shipping).  I connected them in parallel, and then connected 6 inch extension leads to both sides, soldiering everything in place.  I then checked the connections end-to-end with the ohm setting of the multimeter, to make sure the connections were good.

I used the Dremel tool to dig through the plexiglass so that I could screw the circuit board to it.   Lining up the plexiglass with the four pre-drilled holes of the circuit board, I drilled the first four holes.  This way the back of the circuit board (where my solder points are) can't short out on the metal case of the KS-32.  I also added a fifth hole on one side of the plexiglass so that I can loosely attach the entire thing to the inside of the KS-32 (to not stress any connections).

Once the holes were drilled, I put the 4 bolts through the plexiglass holes.  Stacked 4 washers on each bolt (as a stand-off ... other solutions would work just as well), and fed the circuit board (which has four pre-drilled screw holes already) on top.  The nuts are added on top of that.  Pliers and screwdriver are used to tighten the circuit board to the plexiglass.  I added some electrical tape to cover the bolt heads, just in case they make contact with the back of one of the circuit boards inside the KS-32.

Next, I removed the old battery (from the leads that I had put in earlier), though, the leads can be attached directly to the original battery mounts.  Then I soldered the leads together.  I cannot stress enough to make sure that battery + matches circuit-board +, and that battery - matches circuit board -.  I used red and black insulated wires to indicate polarity at every step.

Once everything is soldered in place, do one more multi-meter check to verify that the connections on the battery holder terminals reach all the way to the circuit board.  Then I electrical-taped the movable solder connections on the lead wires.

I then took a thin cable tie, and fed it around a stand-off on the upper circuit board assembly, then through the fifth hole on the plexiglass.  I closed it only to the point where it started to click (not tight).

Finally, I put one battery into one battery holder (it doesn't matter which one - but it does matter how the battery goes in).  Aside, If you made it this far, you must be really into mod projects without pictures, or you are board.  I appreciate it either way.

I closed the KS-32, turned it on ... set some settings, saved some preferences, and then turned it off and unplugged it.  After a few minutes, I plugged it back in, turned it on, and verified that the settings were saved.  Success.

The other battery holder is fully connected, and ready to receive a second battery.  I've set a reminder to put a second battery in, after four years.  I then plan to replace one of the batteries every four years until something else goes wrong, and the keyboard dies.

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