I’ve always loved retro tech, but sometimes working with older video equipment can be… frustrating. That’s why the GBS Control project caught my attention—it takes an affordable video scaler and transforms it into a powerful tool for retro enthusiasts like me. So, when I decided to tackle a long-forgotten V9900 scaler from my project pile, I knew GBS Control was the way to go.
The Problem with Stock Scalers
The GBS 8200, a budget-friendly scaler from the arcade and retro console world, is functional but far from perfect. Latency issues and subpar video quality made it less than ideal for anyone serious about retro displays. Enter GBS Control, an open-source firmware upgrade that changes everything. With just a microcontroller like the ESP8266 or ESP32, you can unlock low latency, improved color accuracy, scan lines, and even web-based remote control.
Why the V9900?
The V9900 isn’t officially supported on the GBS Control wiki, but it seemed close enough to the GBS 8200 to give it a shot. My VC9900 had been sitting around for ages after an initial failed attempt to use it, so I figured it was time to see if I could make it work. Spoiler: it did, and the results are amazing.
Base instructions GBS Control Wiki
The Build Begins
First, I needed an ESP8266. I found one on eBay for an absurdly cheap £3, shipping included. When it arrived, it looked fine despite some shipping damage—nothing a little pin-straightening couldn’t fix.
NodeMCU ESP8266 UK, NodeMCU ESP8266 USA
The first step, according to the GBS Control wiki, was to bypass the RGB input potentiometers. While the instructions suggested a destructive approach, I opted for a cleaner solution by removing the pots and replacing them with simple links, dressed up with heat shrink tubing for a neater finish.
Next, I wired up the debug pin using Dupont cables, which are perfect for temporary connections. The debug signal is sourced from pin 30 of the V9900’s IC6 chip, the MTV230 microcontroller. Once wired, the ESP8266 takes over, unlocking full control of the scaler’s video processor.
Setting Up the ESP8266
Connecting the ESP8266 was straightforward using the diagrams and instructions from the GBS Control wiki. I made custom cables for power and data, skipping optional add-ons like clock generators and OLED displays for now. I wanted to confirm everything worked before adding complexity.
You will also need to close the jumper to put the MTV230 in it’s place, jumper is located next to the two headers to the side of IC6.
The colored blocks, boxed in pink, on the pin out diagram below reflect the wiring and colors I used in my build. For clarity I use White for Vin and Grey for ground connecting to the 5v header.
Installing the GBS Control software was simple as long as I followed the instructions carefully. With everything connected, I ran initial tests using my Amiga 500. Cycling through ROMs and booting up a few games showed promising results—beautiful, crisp visuals with none of the latency issues I’d experienced before.
I powered the board with a Zip-Drive 5v supply, but any regulated 5v supply with a Centre positive barrel jack should work fine.
Making It Practical
While the setup worked, it wasn’t practical—just two boards loosely connected by wires. To fix this, I built a mounting board from leftover plastic from another project (thanks, A2000 undertray!). After marking, cutting, and drilling, I mounted the V9900 and ESP8266 securely.
The result? A compact, reliable solution that handles retro video signals beautifully and outputs them via HDMI. All for less than £25 ($30)—a fraction of the cost of high-end alternatives like the OSSC or RetroTINK.
The Results
The difference is night and day. My repair footage now looks professional, and retro games come to life on modern displays. This build is perfect for anyone looking to upgrade their retro experience on a budget.
