Casio CZ/ VZ/ FZ - Pro Series

Hi Fran, Gordon,

Glad to see you are old-timers form the KorgPolyEx as well just like me! 
:) (waiting for my atomahawk kit to arrive...)

Thanks very much for your suggestions. I found the LED calculator pages 
very informative and useful. I would definitely like to know where the 
5V rail is, but if I can take voltage from then LCD power leads with no 
risk of the LCD getting less voltage than necessary that will be fine. I 
was thinking maybe I could draw current from the stage previous to the 
inverter-transformer (the low voltage) so I could even desolder the 
transformer. But then again, maybe I'm talking nonsense.

As I said, I have no formal knowledge of electronics but nevertheless 
managed to perform various repairs (including fixing pendrives or MP3 
players, almost doing microsurgery to them -- yes, in Argentina you do 
get to do that since electronics are a tad more expensive than in the 
USA). I've even did the MoogSlayer and FM-800 mods on my Poly 800 and 
they work perfectly.

Regarding EL foils, it's been only a couple days since I fitted my Korg 
01W with a new EL foil from Synthlights in Canada. Problem is, I live in 
Argentina and it took more than two months to receive the package (and 
it was in TERRIBLE conditions... luckily the foil works fine). So I want 
to try this alternative solution.

Thanks again for your time and help!

Dave



On 08/12/2010 06:28, Gordon JC Pearce wrote:
>
> On Wed, 2010-12-08 at 03:17 +0000, davidmochen wrote:
> > Hi all,
> >
> > I own a CZ1 with an almost dead EL backlight.
> >
> > What I would like to know is:
> >
> > 1) is there any chance to hack the inverter circuit/transformer so
> > that it could feed a couple LEDs which I plan to place besides the
> > LCD? (more details on that below). AFAIK the input to the inverter is
> > VDC, so maybe disabling the transformer and doing some extra stuff
> > would get the point.
>
> No, because the inverter takes a low voltage and steps it up to a couple
> of hundred volts to drive the EL backlight and LEDs need about two
> volts ;-)
>
> Not only is it a bad idea to modify the inverter, it's not even
> particularly necessary.
>
> > 2) if 1 above is a no-no, where can I get appropriate current from for
> > driving a couple bright LEDs? I've seen some posts where a brand new
> > display with built-in LED backlight was retrofitted into non-backlit
> > models like CZ1000. The on switch was mentioned, but I also saw that
> > also pins 1 and 2 of the LCD can be used for that. Also, could I
> > disable the inverter circuit so as to save some power?
>
> Pick up a DC supply from just about anywhere, including as you say the
> power leads to the LCD. Wire the LEDs up with a suitable
> current-limiting resistor which you can work out from the forward
> voltage and current of the LED and the supply voltage. Or, just run it
> off the 5V rail with a 220 ohm resistor for each LED, that'll get you
> about right. Don't go much below about 100 ohms unless you're using a
> very high-power LED, or you'll cook it. Above about 680 ohms chances
> are it'll be a bit too dim.
>
> > My idea is to keep the existing LCD and fit it with a custom
> > backlight. I've been doing some tests with a tiny rectangular piece of
> > acrylic sanded on one side so as to diffuse light. I placed it where
> > the EL foil used to be and lit it with a small LED lantern. Light gets
> > effectively across it and the LCD gets softly lit so I think if I
> > placed two strong-enough LEDs at both sides of the acrylic I would get
> > a nice backlight.
>
> You can get EL films for other gear like the Akai samplers. I bet if
> you send the old film to one of these guys on eBay they'd cut you a bit,
> or just sell you an Akai backlight to cut up yourself.
>
> > I have only very basic electronics knowledge but am not afraid of
> > soldering stuff. :)
> >
> > Thanks very much in advance for any help.
>
> Well, you like old synthesizers so you're going to need to learn to
> repair them some day ;-)
>
> Gordon MM0YEQ
>
> 


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