Project: RGB Cable for Sony KV-20XBR

Some time ago I acquired a Sony KV-20XBR 20” Trinitron TV. This and the companion 25” KV-25XBR TV were Sony’s first XBR series TVs, top of the line models that (according to the Chicago Tribune) retailed for $899.95 (20”) and $1,199.95 (25”) when they were introduced in the mid-1980s.

One of the interesting things about this set is that it has an RGB input, an uncommon feature for consumer TVs of that era. RGB stands for Red/Green/Blue, a video signal format where the red, green, and blue signals that make up the TV picture are sent on separate wires, allowing for a sharper picture with more accurate colors. In the 1980s, there weren’t many consumer devices capable of outputting an RGB signal, and with the advent of high definition TV, most electronics manufacturers would adopt the component video standard instead. However, there were several personal computers that could output RGB signals, and later there would be some video game consoles that supported RGB (e.g. the Atari Jaguar, Super Nintendo, and Sega Genesis, to name a few).

In order to use the RGB input on my KV-20XBR, I needed to build a cable that would interface to the Sony-specific connector on the back of the TV (labeled “RGB MULTI INPUT”).

This 34-pin connector happens to be the same connector used on many floppy drives (remember those?), and for fast cable construction with these types of connectors, I like to use an IDC connector with a ribbon cable—no soldering required. For the other end of the cable, I decided to use a 15-pin female D-sub connector, since there are many devices that will interface to this connection and it’s fairly easy to still find cables (often referred to as VGA cables). Again, I decided to use crimp-on pins for the D-sub connector for quick construction. Once the pins have been crimped on to the cable, it’s easy to insert them into the D-sub connector, where they lock in place. Here is a photo of the D-sub connector, the ribbon cable with crimp-on pins, and the crimping tool I used.

Having a good crimping tool makes for neat and reliable connections—I got mine at a wonderful Bay Area electronic components store called Anchor Electronics. In fact, I got everything I needed for this project there, including the rainbow ribbon cable (which makes it easier to keep track of which wire is which) and the D-sub connector with crimp-on pins. Stores like Anchor are an electronics hobbyist’s dream—in addition to parts for making up cables, they have a large selection of components, including resistors, capacitors, transistors, and ICs.

Before hooking any new cable up to a live circuit, I check and recheck my connections for correctness using the continuity function of a DMM. I’m often working with vintage gear that is difficult (if not impossible) to repair or replace, so I want to make sure there are no short circuits. With everything double checked, it was finally time to test the cable. I got out my Atari Jaguar, hooked everything up, hit the RGB button on the TV, and…success! (Note the similar ribbon cable to D-sub connector I built in order to access the Jaguar’s RGB output, which also has connections for stereo audio. I added audio connections to the Sony RGB cable after the photo was taken).

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