C64/C128 S-Video Bypass/RF Replacement – DIY Kit

In the Commodore 64, the RF modulator is not only responsible for generating the RF video but also for amplifying and filtering the luminance and chrominance signals from the VIC-II chip. These signals make up the machines S-Video output, the highest quality signal you can get from the original C64 VIC-II graphics chip. Unfortunately, the stock RF modulator injects a lot of noise while generating these signals.

The c0pperdragon RF replacement board available here is a straightforward replacement for both original “bread bin” and C64C systems. It requires no modification to the main board apart from removal of the old RF modulator. Once installed, the board upgrades the machines S-Video and composite video outputs with sharper, clearer signals created by a modern high bandwidth amplification system. Note that RF output will not be available any more but this should be considered obsolete anyway.

In our in-house tests, scope readings show all signals are in spec and clean and the signal to noise ratio measures up to 20dB better than the stock RF modulator.

The upgrade is compatible with classic CRT televisions, the RetroTINK/RetroTINK Pro and the Koryuu.

The upgrade can be used in conjunction with a LumaFix 64 board to further clean up the machines noisy S-Video output. Generally this will make a small but appreciable difference compared to running just the S-Video bypass on its own, but results vary widely between Commodore 64 machines.

Each kit contains 1 x c0pperdragon C64 S-Video Bypass/RF Replacement PCB and 2 x 4 pin header connectors.

If you want the best picture quality with 100% authentic Commodore 64 VIC-II graphics hardware, then you need the C64 S-Video Bypass/RF Replacement!

Commodore 128 users

A number of customers asked us if the kits were compatible with the Commodore 128 too. We asked BetaGamma Computing to look into this and the answer is yes! This mod is fully compatible with the C128 too. Please note however that the VIC chip in the C128 is very prone to jailbars, and installing the bypass board may make this effect considerably worse.

Fitting Instructions

For fitting instructions, see this link.

Installing this upgrade requires soldering skills, please study the instructions carefully and ensure you are confident enough to carry out the work yourself before ordering. Please do not purchase this part unless you are confident with a soldering iron. While community support may be available in our forum, we cannot give technical support with DIY installations, nor can we offer refunds or compensation for parts damaged due to bad/incorrect DIY installations.

If you’re not confident installing this upgrade yourself, we offer a fitting service here.

Open source design developed by c0pperdragon and used with permission. Want to build your own board?, check the Github page here.