How To Repair Kurzweil Pc88 Keys

The youth worship leader called The Unbrokenstring Crew, having wearied all other avenues available to him to get their synth repaired.  Could we step up to the plate and fix the various issues with this unit?

If you look closely, you will run across a fleck of dark-green tape on the East key just above middle C.  That key plays loudly, or not at all.  There is no in-between, which is a problem while playing an offeratory.

Houston, we take a problem.  These batteries take taken their leaking game to a whole new level.

Fortunately, this battery box can be replaced.  Merely how much other stuff has been contaminated with electrolyte?

Nosotros need to split up the case open to look at the wiring and circuit boards.

These screws hold the fundamental bed in identify.  This unit is so heavy that I decided to go some of these out while I was hither.

This is what the inside of a synth looks like.  The battery box is to the left of center of the picture.  Everything is wet.

The 'green tape' issue is resolved by disassembling the primal bed.  Out information technology comes, and it is heavy!

The screws holding downwardly the pitch bike assemblies are located on the bottom of the chassis.  This allowed all the battery electrolyte to be neutralized and cleaned out.

This key bed is from Fatar.  It is 'semi-weighted' and, to me, feels simply similar a real pianoforte.

The key bed is tilted up to proceeds access to the lesser of the assembly.

I labelled these ii ribbon cables B for bass and T for treble.  This corresponds to the left and right half of the keyboard, respectively.

These short jumpers go between 2 long circuit boards.  Note the white zero-ohm jumpers on the PCB.

Now we remove a whole bunch of screws to gain access to the other side of these circuit boards.

The long thin excursion boards are now costless from the key bed chassis.  Nosotros meet the objective of our mission!

These safety strips are push buttons that close a pair of electric circuits when a cardinal is depressed.

There are two button buttons per key.  I button plunger is longer than the other.  When a key is depressed, the amount of time between ane push button and the other is used to derive velocity information for that note.

And here is our 'dark-green record' problem.  The longer push button is torn, and so the keyboard scanner only saw the shorter switch closure.  In a unremarkably-operating keyboard, the longer push closes first, followed by the shorter 1.

New keypad strips are available for this unit.  Afterwards inspecting the entire keyboard, I replaced two of the keypad strips for the octaves around middle C.

All of the strips were removed and the circuit board cleaned.  Notation the pairs of carbon contacts on the PCB.

The key strips must fit securely in a precise orientation.  Note all the piddling alignment nubbins fitting into the PCB holes.

The central bed is ready to exist reassembled.  Annotation the black plastic strips that serve as spacers betwixt the metal cabinet of the key bed and the circuit boards.

This is the treble excursion lath going back into the unit of measurement.

All those piddling screws seen before are re-installed.

The small-scale ribbon cables is reinstalled.  Those big ribbon cables become back on next.

This is really a ground conductor for the pitch wheel assembly.  I constitute it easier to reinstall the pitch wheel associates now, before the primal bed is placed back into identify.

Some of the keys have an aural squeak when they are depressed.  OK, let'south gear up this too!

I've modified a bamboo chop stick to reach into the center of the leap, allowing me to unhook the bottom of the spring.

Springs for the white keys are on either side of the leap used on the black keys, seen in the heart.

Once the spring is removed, the central tin be un-clipped from its hinge.

Very super-secret, highly-technical precision formulated compound is used to lubricate felts and friction points here.

A little bit of the lubricant is sparingly applied to where it needs to go to impale the squeaks.

The long tab actuates the weighted action of each key, giving this fundamental bed its semi-weighted feel.  The shorter tab actually depresses the rubber key pad strip switch seen earlier, to betoken the synth to make a sound.

Dr. Shoen gives the completed synth a trial run in pianoforte mode.  He is very pleased with the keyboard action.

Jacob explores the synth presets.  I call up everyone is satisfied with the repair!

Thanks for reading all the mode to the stop!

CONTACT – David Latchaw EE
281-636-8626

How To Repair Kurzweil Pc88 Keys,

Source: https://www.unbrokenstring.com/kurzweil-k2500xs-synth-repair-and-recondition/

Posted by: ramseywopper87.blogspot.com

Share this post