Gonbes GBS-8200 Basic Setup

This is a support manual for the GBS-8220 – which comes in a one vga port and two port version.
When using this board you want to read all the information in this document – there are many
common mistakes/issues when using this for arcade conversion that can easily be cleared up.
Most common is using a 1Amp power supply or wrong power. This board works best with 5V and at
least 2Amps. Less than 2 Amps will give problems!
Another common issue is Red Color increasing and video issues. Adjusting the "clamp ST" and "clamp
SP" settings of the board will usually correct this.
Other issues are incorrect signal connections.
Who makes these cards?
These are made by Gonbes.
The model numbers are GBS-8200 / GBS-8220. They mostly look the same except the 8220 has 2 VGA
D-SUB 15 connectors in output.
http://en.gonbes.com/product_detail.asp?menuid=94&id=22
What is it?
It's a pcb card for video upscaling, that can convert a 15Khz RGBS input (e.g. from a JAMMA board) or a
composite (YPbPr) signal into a more conventional 31 Khz VGA output, compatible with most modern
monitors and LCD/LED TVs (which no longer recognize 15Khz).
Commonly used to convert old consoles/computers to a VGA signal, upgranding old cabs into newer
monitors, and superguns of course.
How well does it work?
Your mileage may vary. Many people seem to be happy with it but many others have a number if issues.
Outputs 60Hz so may be worse if your input is 50Hz. (I've only tried 60 Hz)
What are the issues?
The upscaling applies a bit of smoothing, which you can reduce using a "sharpness" setting.
When in operation you may see some noise with some pixels flickering. This is barely noticeable (it's
pixels of the output resolution so they're small) and some TVs may correct it (haven't tried).
You may have sync issues if your grounding or power source is not good enough.
Does it slow down the video?
Probably but not as far as I can tell. The movement feels like 60Hz.
I can notice some interlacing in some shadows (ie. for strong black flickering on white) but it's massively
better than the FPS being put out by a Multi PCB for example (30 fps).
(update: using a scanline filter improves the interlacing by hiding some of it. still noticeable but plenty
playable)