E M X P | CMI

Ever since I got my EII I’ve been planning to add an HxC Floppy Emulator. These are some of the reasons:

One of the floppy drives doesn’t work and replacement drives are expensive
an SD card can hold a lot of floppy images
I don’t have a computer with a 5.25″ drive, so I have no way of transferring all the EII images I’ve got (could be solved if I get my Mac SE 30 and the serial thing working)

As the EII uses 5.25″ floppy drives, the connectors aren’t the same as for 3.5” drives. To solve this you basically have three alternatives:

Create a new custom cable
Create some kind of extension/adapter cable
Modify the original cable

There’s a comprehensive manual from E M X P describing everything that you need to know about the HxC installation, including diagrams of the cables, whichever one you choose. Since I don’t like messing with the original one I chose to create one from scratch. I skipped the extension/adapter route since it would require a female 5.25″ connector, and I could as well create a whole new cable since I was messing with cables anyway. It’s also worth noticing that the cable is very long, almost a meter, which makes it nearly impossible to find a standard floppy cable and just add an extra 5.25″ male connector. In the picture below, taken from the manual, alternative 1 is the route I took. Alternative 2 shows the extension/adapter cable route.

Drawing of the 1) custom floppy cable that I make 2) The extension cable alternative. Screenshot from the E M X P manual (a must for everyone doing this conversion)

Parts

About 1 m of 40-pin ribbon cable
Two standard 3.5″ floppy female connectors
One 5.25″ floppy female connector “34-way card edge connector IDC”
Lotharek REV F HxC drive (REV F is the 3.5″ floppy version). Buy it directly from Lotharek’s homepage. I should cost around €100, but I’ve seen “unofficial resellers” on eBay selling them for €150-200 – that’s a scam.
5.25″ to 3.5″ adapter bracket, like this (I already had one from a computer chassis)
4 pin Molex to floppy power adapter, like this (I had one lying around, probably included with a PSU)

Close up of a standard 3.5″ IDC floppy connector. No special tools are needed, just put the ribbon cable through and squeeze the connector. I used a vise to create an even pressure.

The “edge” connector that’s used on 5.25″ floppy drive cables

Disassembly

First thing to do is to up open up the EII, which is a very simple process. Just a couple of standard Philips screws at the back and underneath. Then take the top of. Also locate the 4 screws that attaches the “floppy tower” to the chassis to remove it.

The floppy tower is detached from the EII’s chassis.

The connector on the right lower board that goes to the floppy drives.

At the middle of the main board, above middle C, a flat cable is folded, then going to the left, under the floppy tower and up to the drives. Remove this cable and use it as a model for the new cable.

Making the new cable

Prepare the flat cable by removing 6 of the wires to “convert” it from a 40 pin to a 34 pin flat cable. Then fold it at the exact same places and put the connectors at the same place, with one big difference – where the original cable has a 5.25″ for the upper drive, replace this with a 3.5″ connector. I used a vise to evenly squeeze the connectors to the cable. Make sure you orient the connectors the right way. Look for a little plastic piece between the 2nd and 3rd pins on the 5.25″ connector.

Removing six wires to make the 40 pin cable become a 34 pin cable

Look for a little plastic piece between the 2nd and 3rd pins on the 5.25″ connector (see arrow).

Swapping the faulty 5.25″ drive

The lower floppy drive didn’t want to load a disk that I know worked in the upper floppy drive. Therefore I swapped them and carefully set their jumpers right. Now the lower one worked, but not the upper. Perfect, since my intention is to keep a working 5.25 floppy in the lower position and the floppy emulator in the upper position.

Testing the upper (working drive) in the lower position with jumper changed. The original lower floppy drive was dead.

The two original floppy drives. The lower one (left one in the photo), was faulty. Too bad, since the extra floppy added $650 to the $7995 retail price back in 1984…

The faulty floppy drive with serial no 143922. Maybe it just needed cleaning, I don’t know – I’ll keep it as a spare or something. It’s amazing the upper one works after 30 years…

5.25″ adapter and HxC metal work and jumper

I’ve used the HxC in lot’s of different samplers, and it has never properly aligned with the machine I’ve put it in. It always extends a couple of millimeters outside. So I decided to modify the HxC by drilling new holes in its metal chassis. For this I used 2.5 mm cobalt drill and used the adapter as a template. I chose this particular adapter since its pattern on the plastic matched the EII best.

When the HxC is mounted in the adapter (or any other machine), the holes don’t align (see the arrows), which makes the HxC extend a couple of mms outside the adapter/machine.

See the correct jumper setting of the HxC in the upper right corner. This photo also clearly shows that the holes don’t align properly.

The HxC has new holes drilled and now fits perfectly in the 5.25″ adapter. The original holes made the HxC extend a couple of mm outside the adapter. This is not the fault of the adapter, I’ve hade the same issue in all machines I’ve used the HxC in.

Also set the jumper on the HxC to first position, as in the photos.

Floppy power adapter

For power to the HxC, a Molex to floppy power adapter was needed. Luckily I had a few of these lying around, probably included with some PC power supply, but never used. They can easily be found on eBay for a dollar or two. It’s simply connected to the Molex power connector that was previously connected to the now removed 5.25″ floppy drive.

Assembly

Simply reassemble the EII the other way around!

Tag Archives: E M X P

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