Notes on Casio CZ-1 display replacement
2016-12-29 by contact@...
I just replaced the old display with broken backlight on my CZ-1. Here are some notes.
To replace the display you need to open the button panel. This is
attached with 9 screws with Philips 2 heads. Four of those are on the
top, all the way on the side. Five in the back, evenly spaced in a
single row. The middle back screw is underneath the cartridge slot.
There are a lot of cables running between the button panel and the
main case. I found that by carefully propping up the button panel I
could get to the display without having to undo any other cables.
The display is held in place with 4 Philips 1 screws. One of them has
a ground connector on it, be careful when removing this screw that you
don't loose the little locking ring.
The original display uses an electroluminescent backlight powered by
'high' voltage. There is a voltage converter on the MIDI board (you
can see its little transformer) and a 2-wire cable running to the
display to power the backlight. With a modern replacement screen (with
LED backlight) you don't need this high-voltage power supply. I found
that the transformer starts making a whining noise after removing the
old display, I think I will just remove the transformer.
The character display itself uses 14 wires soldered to the board with
a 14-pin connector on the other end. I chose to reuse the cable
assembly of the old display; that meant desoldering the 14 wires from
the old display and soldering them to the new display. This was not
difficult. But pay attention: new boards have 16 pins, not 14, and you
want to skip pins 15 and 16 (LED backlight, see below). When ignoring
pin 15 and 16, the rest of the pins should be in the same order as the
old display.
It seems to be common for modern replacement displays to have the
option to power the LED backlight from pin 1 and 2 (which by default
power only the character display). On my display there were jumpers
(big SMD 0 Ohm resistors) that I could desolder and resolder to send
power straight from pin 1/2 to the backlight. Desoldering SMD
resistors is a little tricky compared to through-hole; I managed in
the end by heating the resistor edges with a soldering iron and gently
prying the resistors up while heated. A hot air desoldering tool would
be the proper way to do it I suspect but I don't have one of those.
If you don't want to use the jumpers or if your display does not have
them you can probably also run two short wires from pin 1 and 2 to 16
and 15.
The display seems to be a standard size: 84 by 44 mm. The one thing to
look for in a replacement besides the size is the number of
connectors: you want there a row of 16 'holes' (pins?). Not all 84x44
LCD's have the 16 pins.