Casio CZ/ VZ/ FZ - Pro Series

Hi Phono,

check http://www.midi-rakete.de ...

Well, I guess the crashes have nothing to do with the backlight unless it's not 
built in properly. Those backlight needing quite some power and when having a 
short circuit with the casing you probably get misterious crashes like I 
experienced them with my CZ-1...

...Summa


On 21 Apr 2004 at 10:37, phonophobie wrote:

> Hi,
> I have to replace the Backlight Display of the FZ10M. I just found a
> review from someone saying that the problem will come back soon. Maybe
> someone could comment on that:
> 
> ___________________________________________________
> 
> "Graham Meredith  a hobbyist user from Australia writes:
> 2141*graham_meredith@... (remove 2141* from address to
> contact) ****** Design fault info ******
> 
> Read this all you FZ-1 owners who are having mysterious crashes of
> your sampler, or corrupted or or glitching samples, I figured it out a
> long time ago, here's your fix:
> 
> I bet there must be very few FZ-1 and FZ-10M's still around by now,
> that still have the screen backlight working. I replaced mine twice.
> This is a hardware design fault in the fluorescent backlight panel
> behind the display screen. The backlight is cheap ($15) but I doubt if
> you can get them from Casio now. Maybe someone can find an alternative
> supplier. They're faulty, any way. Or perhaps the circuit that drives
> them.
> 
> What happens is that over a period of time (about a year) the
> backlight gradually fades. Eventually it doesn't work at all. What is
> happening at this point, or sometime after, is it begins to increase
> in its internal electrical resistance.
> 
> The circuit that powers it is a 90 volt DC supply, that is created by
> using one of the 12V supply rails on the main circuit board, which is
> passed through an oscillating transistor, then a small step-up
> transformer from 12V AC to 100V AC. A regulator circuit then converts
> this to about 90V DC. This powers the backlight.
> 
> What happens is that as the backlight fades, its internal resistance
> rises. The oscillating transistor that boosts the voltage to 100V AC
> is designed to operate with a specific load from the backlight
> attached to it. If the resistance increases it, it basically becomes
> an open circuit, and causes the oscillating transistor to oscillate
> out of control. This is heard as a high pitched audio buzz coming from
> the display (not through the audio outs of the sampler). At this point
> the screen goes all blurry and the sampler crashes, and the noise will
> continue. The machine needs to be switched off.
> 
> My suspicion is that this type of backlight has a design fault, or the
> power supply voltage has been designed too high for this particular
> brand or type of backlight.
> 
> **** The Remedy ****
> 
> You have to do 2 things:
> 
> 1) disconnect the backlight and remove it (easy).
> 
> 2) Unsolder and remove the oscillation transistor and also the small
> transformer associated with it from the circuit board. (a bit more
> difficult, but any friend with good soldering and electronic kit
> building skills can do it).
> 
> I have the electrical schematics for the FZ-1, anyone who wants them
> can email me and I'll scan them and email them for you, to help with
> fixing the circuit.
> 
> Comments:
> 
> A fantastic retro sampler, really easy to use. I bought mine back in
> 1992, and I was a complete novice to sampling. But when I bought it,
> it was a whole week before I needed to open the user manual! And that
> was to to complex cross-fade stuff. It was that easy. I love this
> thing, except for the display issue, which isn't a problem now that I
> disabled the backlight.Graham "
> ___________________________________________________
> 
> 
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