In-Depth Look: Sega CDX

Sega CDX

The Sega Genesis CDX, as it’s known in the US, is a combination unit that consists of a Sega Genesis, Sega CD, and portable CD player all wrapped up in one small unit. The system was known as the Sega Multi-Mega in Europe, the Sega Multi-Mega CDX in Brazil. Retail price in the US for the unit at launch in 1994 was $399. The European model lauched a year later in 1995. Although the exact number is unknown, as Sega has never released production numbers for the unit, it is believed that 10,000 units were created world-wide and 5000 of those 10,000 units were sold in the US as the Sega CDX.

In the Box

In the US, the Sega CDX shipped with the console itself, a DC power adapter, and a stereo composite video cable. Also in the box was a Sega 6-button controller and three Sega CD pack-in games: Sonic CD, Sega Arcade Classics, and Ecco the Dolphin.

The power adapter designed for use on the Sega CDX is Sega model number MK-4122. Specs on this PSU are 9.5V DC 1.5A with + tip and – ring. If you purchase a CDX without the power adapter, the MK-4122 is rather hard to find. It has been confirmed that Sega part number MK-2103, the 10V 0.85A PSU that comes with the 32X and some other Sega consoles, will work with the Sega CDX. There are some arguments regarding using this PSU with the CDX though. Some claim it will instantly fry the CDX, will otherwise damage the unit, or cause problems over time. I have tested my Sega CDX with the MK-2103 and can confirm it works.

The AV out port on the Sega CDX is the same pin layout as the Genesis 2 and Sega 32X, and provides composite video output as well as stereo sound. The port does not have the capability of S-video output, although there do exist modification guides for the Sega CDX to add S-video output. Due to the cramped nature of the CDX internals, adding S-video output typically results in losing the capability of using the ability to use AA batteries with the unit, as the AA battery compartment is the only space avaialble inside the unit to store the components required for the modification, including the S-video port itself.

Physical Layout

As stated, the Sega CDX was a combination console containing both the full functionality of a Sega Genesis as well as a Sega CD. The unit is capable of playing Sega Genesis titles via the cartridge slot in the rear of the unit, and can also play Sega CD games via the top-loading CD drive on the top of the unit. Even though the Sega CDX can be powered by two AA batteries (explained in further detail below), the unit must be powered with AC power and connected to a TV in order to play Sega Genesis carts or Sega CD games.

At the rear of the unit is a battery compartment for two AA batteries. When the unit is powered by two AA batteries, it can be used as a portable audio CD player. The CDX features a headphone jack with an adjustable volume control and a line level audio output on the right side of the unit. CD player controls are located on the top of the unit near the front, and consist of an open button for the CD door (mechanical, not electric), previous and next track buttons, a play/pause button, a stop button, and a reset button.

A small LCD is located in the top center of the unit near the front. When playing a game this window displays the word “Game” and when playing an audio CD it displays the track information. The power button is located on the front of the unit in the center, and is a two-position on/off switch. On either side of the power button are the standard Sega Gensis style controller ports. On the left side of the console is the AV out port, and on the back of the console is a port for connecting the AC to DC power adapter. Unlike the sides and top of the console, which are plastic, the bottom of the Sega CDX is black steel and contains only a sticker with FCC information, serial number information, and Sega contact information. There are no expansion ports anywhere on the unit.

Technical Specifications

Because the CDX is essentially a Genesis model 2 and a Sega CD packed in to a single device, it shares the same technical specifications as the Genesis and the Sega CD. The CDX contains a pair of Motorola 68000 CPUs, one running at 7.67Mhz (the Genesis CPU) and one running at 12.5Mhz (the Sega CD CPU). The unit is capable of displaying 64 simultaneous on screen colors out of a palette of 512 possible colors. The motherboard for the CDX has obviously been greatly condensed, but it does contain backwards compatibility with the Zilog Z80 CPU in addition to the two Moto 68000s, which allows Sega Master System backwards compatibility (described below). In addition to being able to play Sega CD games and audio CDs, the CDX can also play CD+G CDs, which were more common in Japan than in the US, as CD+G is typically used for karaoke discs.

32X Compatibility

The Sega CDX is compatible with the Sega 32X. When using a 32X with the CDX, the RF shields are not required for the combination to work properly. The spacer that comes with the 32X, which is used to make the 32X seat nicely on the Sega Genesis model 2, is also not used when attaching a 32X to the Sega CDX. Although the combination CDX/32X works properly, the US manual for the 32X states that it is not compatible with the Sega 32X. The common explanation for this is that Sega never got FCC approval in the US for the combination of the two units. This makes sense, as the RF shields were required for Sega to get proper FCC clearance for the Genesis/32X combos (even though the RF shields weren’t needed for those to function properly either), and it was probably easier for Sega’s official stance to be incompatibility between the 32X and the CDX even though they knew it would work.

When using the 32X with the CDX, the 32X plugs direcly in to the Genesis cartridge slot on the back of the CDX, and the Genesis model 2 AV cable that comes with the 32X (the short cable that connects the AV Out jack on the Genesis model 2 to the AV In jack on the 32X) is used to connect the two units together in the same fashion as the Genesis model 2. As is when being used with the Genesis, the 32X requires it’s own seaprate power supply when connected to the CDX, so you’re still left with two large AC/DC power adapters that need to be plugged in separately. The CDX AV cable can then be used on the AV Out port on the 32X to connect the combination to a TV.

Though this combination works – there exist a couple of minor flaws when using the 32X and the CDX together. First, the combination is somewhat top-heavy and tends to want to fall to either side with little help. If you are using the CDX with a 32X, it’s probably a good idea to position the unit so it won’t fall on the floor if it tips over. I.e. – no narrow tables. Another down side of using the two units together is that the CD door will not open fully due to the fact that the 32X extends over it. You will likely finding yourself temporarily removing the 32X from the CDX in order to change out Sega CD games.

Master System Compatibility

The Sega CDX is also capable of playing Master System games via Master System converter cartridges. The official Master System converter released in the US only works on the Sega Genesis model 1 due to the way it’s shaped (it does not work on the model 2 or the CDX). In Europe Sega released a Master System Converter II that was comaptible with the Genesis (Mega Drive) model 2, but the US never got that item. To play Master System games on the CDX, you will need to purchase a third party cartridge-shaped Master System converter. Every one of the third party cartridge-shaped Master System converters that I’ve seen do not contain card slots for Sega Card games, so if you want to play these on the CDX you’re probably out of luck.

Rarity / Collectability

Although Sega CDX units are fairly rare, they are far from impossible to find. In the past 6 months or so I’ve never seen less than 1 or 2 on eBay at any given time. That being said, I’ve also never seen more than 4-5. Lose consoles go anywhere from $150-$250 depending on condition. Consoles that are in excellent shape and are complete in the original boxes with all packaging material in good shape typically fetch anywhere from $750-$1500. I have yet to see an unopened boxed unit for sale, but am guessing that the price on one of these would be higher than all but the most avid (and affluent) collectors would be willing to pay.

If you want a very well built all-in-one console from Sega that will allow you to play Genesis, Sega CD, and (with adapters) 32X and Master System games, and want a system that has a high level of “cool factor,” you can’t beat the Sega CDX. Just make sure that when you buy a CDX, boxed or not, that you get a guarantee from the seller that it works 100% – or better yet if you can, test the unit yourself. There are a couple common problems with the Sega CDXs, including (like any other CD based system from the 90s) CD lasers getting out of alignment or broken which results in the system failing to read discs. Another common problem involves internal power supplies in the units going bad, which some attribute to incorrect power supplies being used with the units. If the unit you’re purchasing powers up and plays both CD and cart based games, you should be good to go.

Final Thoughts

Given the fact that the CDX was released so late in the Genesis’ lifetime, given the fact that the Sega CD itself had lost a lot of popularity by 1994, and given the fact that Sega was charging $399 for the console, it was easy to see the writing on the wall – the unit didn’t sell well, not many were made, and not many good examples exist today. When the unit was released in 1994, the 32X, Sega Saturn, Sony PlayStation, and Nintendo 64 were all within a year (give or take) of release, so there weren’t many games willing to shell out $399 on last-gen, dying game system. It’s unfortunate, beacuse the console is – in my opinion – one of the coolest pieces of Sega hardware ever made.

Personally, I love the CDX. It’s one of the gems of my colletion. I remember seeing them in the store when they were released and thinking “That is so cool! I really want one of those!” Of course the $399 price point was cost prohibitive for an 11 year old, so I wasn’t able to get one then. You’ll run in to two types of people in regards to the CDX – the people who saw them in the mid 90s and thought they were the best things ever, and people who have never heard of them. Either way, people who care about old school video games get really intrigued when they see one of these, and the CDX always tends to spur good conversations.

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