[sdiy] Digidesign Focusrite control 24 schematics

[grant musictechnologiesgroup.com]

Now I know what you are talking about.  " High‑intensity, four‑character LCD displays above each rotary control."
We thought you were talking about the 88888888 7-segment LEDs.

https://www.ebay.com/itm/175869901982

Do you have better pictures of what you have torn apart?  There are, what appear to be, a lot of little MCUs in that "board". Maybe just programmable logic chips.

GB


On 6/11/2026 8:04 AM, H.Sergio Alves wrote:
I’ve been trying to reverse engineer it… I have a bunch so one was the victim… unfortunately since I don’t have enough knowledge I’ve resorted to ChatGPT to help…
I’ve managed so far to pin out basics and get the circuitry on the lcd sorted now it’s the way it works that we struggling with…

The lcd is composed by 4 digits on a 8x5 dot matrix with a custom die on the base of the glass
It’s controlled by a small Zilog through (?) a HEF4053.
Next step is going to be reverse engineering of the main board where these are installed and figure out the pinout for the lcd itself… then using a more modern mcu try to speak and show some digits…
Long way to go but tons of fun so far… and learned a lot :)

On Tue, 26 May 2026 at 14:05, grant musictechnologiesgroup.com<http://musictechnologiesgroup.com> <grant at musictechnologiesgroup.com<mailto:grant at musictechnologiesgroup.com>> wrote:

Standard single-digit guys if this is what you are asking about:

https://www.ebay.com/itm/175869902159

GB

On 5/26/2026 5:31 AM, Roman Sowa via Synth-diy wrote:
> Are you sure they are LCDs? If so my first bet would be on typical
> HD44780 interface. From the blury pictures I see they look to me a bit
> like LED matrix, something like HDSP2131 - but those are 8 digits.
>
> My secong guess is that any customization was related only to size,
> leaving control protocol the same as common displays.
>
> Roman
>
> W dniu 2026-05-26 o 14:00, H.Sergio Alves via Synth-diy pisze:
>> Long shot but does anyone have the schematics for this monster
>> controller? Spoke with Avid and Focusrite and none of them have them
>> (I know it’s wild but hey…)
>> I’m looking to reuse the small 4 digits lcds but need to figure out
>> how they’re connected and the protocol used to speak with the Zilog..
>> spoke to the manufacturer of the screens but since these were made
>> custom and over 20 years ago they don’t have any documentation
>> available anymore.
>> Thanks for any help you can provide In advance :)
>>
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