GameRoom Articles
GameRoom Web Store
RetroBlast Reviews
RetroBlast Articles
Game Room Links
File Downloads
Site and Contact Information

RetroBlast! Review:

JROK's RGB to NTSC Encoder


One thing I like about the arcade game community is that people are always coming up with new and interesting ways to play video games. By taking something and making it do something it’s not supposed to do, people are making completely unique game experiences, like putting a console in a JAMMA cab, or playing Arcade PCBs on their TV with a Supergun. A Supergun is a device that lets you play an arcade PCB on your TV, complete with controls and video and sound outputs. Many people have even taken to building one of these devices themselves. Arcade games output monitor signals in pure red, green, and blue signals along with sync. But for some reason, when it came to television, we Americans decided that we need a proprietary encoding method, called NTSC. So, in order to play arcade games on your TV, you need a special device to encode your RGB signals to NTSC. The most important part of any supergun, is the RGB – NTSC encoder, or for our UK folks a RGB – PAL encoder. This is where the JROK comes in. There are a few RGB -> NTSC encoders on the market, but the JROK is one of the most popular and JROK has been making them since 1998. (Much like Frankenstein refers to a creation and its creator, JROK refers to a product and its maker.)


The JROK encoder was very nicely packaged, and came with all the wire leads you will need, which saved me a lot of time crimping wires into pesky Molex connectors. Also, you can order separate panel mounts for your project through JROK at $1.75 each. The mounts I received were gold plated and looked to be of great quality. JROK is very flexible with the ordering too. You can specify your card with or without on-board jacks, so that you can panel mount your jacks separately and save on some space.

JROK's RGB to Video Encoder

Included in the package.


The JROK Version 4.0 converts arcade games’ RGB signals into Composite, S-Video, and Component Video. Version 3.1 is also available which is only composite and s-video, and comes with a lower price tag. I tried the JROK (v4.0) using several games and in all three video modes. Arcade PCBs I tried were a Neo Geo MVS 2 slot, Teenage Mutant Ninja Turtles, Rampart, and Mortal Kombat. I had some problems trying to get a clean composite video signal, but JROK was very willing to help me out. Colors were appearing correctly, however the image wasn’t stable, and there was a strange rolling effect with the picture. Please see this video.

JROK told me this is usually a grounding problem, however after triple checking my grounds, doing some redundant grounding, and trying multiple TV’s, power supplies, PCBs, encoders, cables, and connectors, I was still unable to get a decent image with composite. No worries though, in case you didn’t know, composite video sucks anyway. If you are looking for an encoder and all you have is composite, just know that the composite video on the version 4 requires some strict grounding that I wasn’t able to figure out. I unfortunately can’t speak for the version 3.1, but I imagine this might be a problem for some people. Really, if all you have is composite, you should upgrade before you play arcade games on your TV. As for S-Video and Component, colors were crisp and clear, and the image was completely stable. I had no problems with them, and they worked immediately.

Playing Neo Geo games on a huge HDTV almost made me cry!

I really liked that pots are on the board to adjust your R, G, and B signals. Although everything looked good out of the box, it’s nice to know its there for some tweaking sessions. One thing I noticed was that on certain games either the sides or top and bottom would be cut off a little bit. I asked JROK about it, and it may require you to adjust your TV settings a little bit. Now I know most TVs aren’t as flexible as arcade monitors when it comes to V-Size and H-Size, but different arcade boards output their signals in different ways. This is the major limitation of the low price point of this encoder. Also, the encoder will not “flip” a vertically oriented game like Pac-man, so you can play it horizontally. However, additional image size and orientation processing is a feature that will put you well into the $200+ range.

A couple of things to be aware of:

  • This unit does not work with medium resolution games. Most medium res games will let you play it in standard res mode with the flip of a dipswitch (e.g. Atomiswave, Midway games like Blitz, Gauntlet, etc.), but Sega games like Virtua Fighter are a no-go.
  • Certain later Midway games such as Smash TV, NBA JAM, Mortal Kombat (1-3) output at a vertical sync frequency of around 56 Hz, whereas the majority of the games use 60Hz. These games are incompatible with some Sony TV sets, most notably the Sony WEGA series. I had this problem on one of the test TVs as well, which was a late 90’s Magnavox. These sets cannot sync to this frequency and the picture will roll vertically. This isn’t a problem with the encoder, but a problem with the TV. Some encoders will not even work with these boards, but JROK runs fine, provided you don’t have a Sony WEGA. The video below demonstrates the problem.

At the time of this writing, JROK has released version 4.1 of his encoder. This encoder is functionally identical to 4.0, but JROK has just moved some things around for optimization.


The JROK (v. 4.0) encoder offers a very flexible package encoding the RGB signals into three different video modes. The result is a very flexible and very affordable encoder.


  • Great price-point
  • Convenient packaging of included wires and mounts available
  • Small footprint
  • Allows for on board or off board video mounts
  • All three popular video signal formats supported


  • Composite video grounding sensitive


  • JROK RGB-NTSC Encoder Version 3.1 - $65
  • JROK RGB-NTSC Encoder Version 4.1 - $85

RetroBlast! Recommended Links:

JROK's Website

A Great Video Signal Primer

Return to Reviews