[sdiy] Glowing diode on Casio CT-510 analog board?

[Benjamin Tremblay]

This topic could easily split two ways.
1) the CT-510 is my practice dummy to get me in shape to fix the analog board on a Casio CZ-230s, a more interesting specimen.
2) I have never built any NLC projects but spent an afternoon daydreaming about the LED-controlled Bong0 module. The idea of using glowy things to generate sound is intriguing. I love the rubbery flabby sound those modules make.

Benjamin Tremblay

> On May 22, 2023, at 9:03 PM, Benjamin Tremblay <btremblay at me.com> wrote:
> 
> Here it is.
> <image0.jpeg>
> 
> 
> Benjamin Tremblay
> 
>> On May 22, 2023, at 8:41 PM, Benjamin Tremblay <btremblay at me.com> wrote:
>> 
>> Sorry if this is way way way off topic. I’m trying to fix this Casiotone keyboard and there are no schematics. The power supply seems to be putting out around 4 volts. The logic board runs but the 4558, 4066, and power amplifiers seem inert. 
>> I’m trying to trace the power supply. Unlike most Casios from the 80s, the 5 volt regulator is just a zener diode, not a 7805. There’s one more non-zener diode on the board, and it’s faintly glowing red (!)
>> I know all diodes emit radiation when they are operating, but this one has such and led-red color.
>> Were such diodes ever used to indicate an overload on the board? I was more interested in fluorescent hair gel than power supplies  when this keyboard was made. 
>> <image2.jpeg>
>> 
>> (Lower left corner, a normal looking glass diode)
>> Benjamin Tremblay