About a year ago I decided that i wanted to build my own GBS-Control with built in HDMI out and USB-C for 5V power, mainly to see if I could. Since I had an old GBS-8220 that never worked I decided to disassemble it uh... not so gracefully.
Which lead me to design the first version of my own GBS-C:
I decided to add two multiplexers, one to isolate the
SCART and VGA inputs from one another and one to
switch audio from SCART to component.
The SCART input has an
EL1883IS for sync separation. The
Si5351 clock generator is also on board.
On the output side I used a
THS7373 and a MacroSilicon
MS9288A for HDMI (Spoiler alert: unsuccessfully). On a side note, always check the datasheet to see if you actually used the correct footprint.
After assembling the most essential parts I plugged it in and to my surprise there was an actual video output!
After reworking the TV5725 and RAM the image cleared up and looked as expected.
Sadly I couldn't get the MS9288A to work at all, which wasn't too surprising since I couldn't find a datasheet or schematic and I didn't have a working board with the same chip.
So I started looking for alternative chips, preferably with schematics and/or a datasheet. What I found was the
ZY5621 and a single listing on aliexpress (which has since vanished as far as i can tell).
I just copied the schematic and created a small board to see if it actually works and it did!
After all that my GBS-C ended up looking like this:
Not exactly pretty but it works fine.
However the recent release of the
Shinobi-Scaler made me want to revisist this project.
And this is the result:
I removed the VGA and Component inputs since I don't use them and only left one video output using HDMI.
Very pleased with the results even though there are still some things to fix on this PCB.