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

Roman Sowa modular at go2.pl
Tue May 23 14:29:12 CEST 2023


Et voila...

this photo was taken in 1999 with borrowed digital camera

Next year will be the 30th aniversary of finishing that synth, good 
excuse to open it again and make hi-res photos, maybe even fix the 
corrupt patch memory problem too.

Roman

W dniu 2023-05-23 o 12:02, Adam (synthDIY) pisze:
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>> On 23 May 2023, at 5:52 pm, Roman Sowa <modular at go2.pl> wrote:
>> FWIW, back in the 90's I used 4 LEDs to create expo converter to drive VCF. Turned out to be accurate enough for the filter. And it looks so cool when played, especially with deep LFO. Too bad I have to open the case to see it.
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> (falls off chair..)
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> Roman, you know you can't get away with statements like that without showing us photos! C'mon!
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>> Roman
>>
>> W dniu 2023-05-23 o 02:53, Benjamin Tremblay via Synth-diy pisze:
>>> Here it is.
>>> 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
>>>>
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