Introduction

The Kurzweil K1000 is a classic synthesizer series that was produced from 1988 to 1992. It was made in two formats/versions: keyboard and rack.

Even today, there's a good number of musicians keeping it in the studio because of some incredibly good (even for today standards) multi-layered sounds the machine can produce.

One of the recurring problems with these synthesizers (both in keyboard and rack form) is the display electro-luminescent backlight running out.

In this Instructables I will show you how to replace the factory Kurzweil K1000/1200 series display with a modern LED backlight LCD display. This will keep your synth usable (and attractive).

I will also share with you a PCB to speed up the replacement process.

Let's go! :)

Seiko M1632 Vs New HD44780 Display

The factory display Kurzweil installed both in K1000/1200 series sinthesizers was a Seiko M1632 display.

This display is based on an Hitachi controller (ASIC): the HD44780. This is still used today on those displays commonly used for DIY project.

The main differences between the Seiko EL backlight display and modern LED backlight display based on HD44780 are:

- Pinout: the two displays have a different pin position and pinout (signals are the same however)

- Backlight: the old backlight was electro luminescent (EL), while the new one is LED. This asks for contrast control and a different voltage.

- Phisical: the new display has different dimensions

In the following we will find a solution for every single difference.

Pinout and Backlight

Look at the pinout comparison. With the exception of the backlight, all the signals (voltages and data) are the same.

The only main difference is the physical pins position.

For what concerns the backlight, the new display asks for a contrast control. This can be achieved with a simple voltage divider.

To help in this part of the project, I have realized a PCB with screen printed pin positions. Simply solder cables straight from the new display pins to the corresponding PCB pins and you are good to go.

The board also hosts the contrast voltage divider the LED backlight asks for.

Please notice that the PCB is double-faced. Populate the board accordingly to the type of K1000 (keyboard or rack) you are going to install it into!

Warning! Kurzweil K1000 keyboard and rack versions have reversed pinouts. The PCB must be assembled in the right direction for the synthesizer type you are going to install it on.

Warning! By connecting a K1000 keyboard to the PCB assembled for a rack version, you will fry the display. It will go very hot and it could injury your skin in case of contact!

New Display Physical Modifications

The old, factory, Seiko display and the new one are physically different.

Installing it in a K1000 keyboard or K1000 rack asks for cuts on the new display board, at different positions. In particular:

- K1000 keyboard: cut the bottom part of the display PCB

- K1000 rack: cut the bottom part of the display PCB and both sides

.

I used a mini driller with a little grinder on top for this operation.

In case of the keyboard version, you will additionally need to drill three mounting holes, or glue the display onto the original synthetizer display board.

In case of the rack version, the only method I could think of to install the new display was the use of hot glue and some 6 mm spacers. It works well and don't ask for irreversible modifications to your valuable instrument.

Warning! While drilling PCBs always wear mask, protective eye glasses and gloves. A lot of dust will be produced. The drilling operation is dangerous also because of the small dimension of the display.