Connecting a Standard Mac Floppydrive to a Powerbook Duo

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The Powerbook Duo 280c is a splendid thing, small, light(ish) and powerful enough for most tasks (except Quake 3). But if the system software gets trashed you're completely stuffed unless you have one of three things:-

1) A full sized Dock

2) A minidock with SCSI slave cable and a second Mac or external drive to connect it to

3) A mini or floppy dock and a HDI-20 floppy drive

I have a floppy dock and external floppy. But the floppy drive is a little dodgey, although it served it's initial purpose (installing the OS after a total crash).

The initial problem with the floppy drive was that it refused to read any disks. Further investigation lead to the discovery that the small piece of plastic that slides the metal disk cover across had in fact broken off. The only way to get it to read disks was to pull the metal cover off the disks (not recommended, but it did the job). The drive has since failed totally.

So I thought that there must be a way of connecting an ordinary Mac floppy drive (superdrive) to the Duo floppy cable. And there is.


**Disclaimer**

*PLEASE NOTE*
I am not responsible if you follow my guide and blow up your Duo, or kill yourself. You should verify all connections and voltages for yourself using a multimeter.


What you'll need

A broken Duo floppy drive (no point using a working one silly)

A standard Mac floppy drive with cable (from any model you like, except a 512k, Plus or early SE as they are only 800k drives)

A 12v and 5v power supply (see below)


Things you should know beforehand

The Duo floppy only requires 5v DC power to operate. This is fed from the Duo itself through the HDI-20 cable. A Superdrive requires both 5v and 12v to operate, so some kind of extra PSU is required. The 5v supply that the Duo kicks out isn't powerful enough to feed the 5v on the Superdrive, so we recommend using some kind of PeeCee or Mac PSU. Something like an old external SCSI case would be ideal. I used an old external CD-Rom case.


What you do

Firstly you'll need to open up the Duo floppy drive.

This is done by first removing the hinged cover on the front of the drive, you just need to prise it off. You'll then see a hollow black pin on either side. Remove these by prising them out with a small screwdriver. The rest of the case is then just clipped together and can be prised apart with a wide flat screwdriver.

Once the case is open you'll see the cable. Cut the wires as close to the brown connector as possible so you have the maximum length of wire to work with, and remove the cable. Then strip the ends of the cables ready for connecting to the Superdrive cable. How you connect the two leads together is up to you, I used strip connectors to make the job easier.

Next take the flat cable from the Superdrive and cut one end off. Then separate the wires carefully *but not completely*, and strip the ends.

It is now just a case of connecting the correct wires together. The Duo cable is colour coded as explained below. The Superdrive cable has a red stripe on wire one, the rest of the wires then follow in sequence up to 20. This is why it is important not to completely separate the wires, if you do you're just making hard work for yourself.


The Duo HDI-20 Cable

The above picture shows the pin numbering on the HDI-20 plug. You have to hold it upside down to get pin 1 in the top left. Pins 5, 10 and 20 are not fitted.

The table below shows how to connect the two cables together.

Duo HDI-20 Cable Pin No.

HDI-20 Colour Code

Superdrive Pin No.

Notes

1

Orange / black dot

1

2

Orange / red dot

3

3

Orange / black dash

5

4

Orange / red dash

7

5

*NOT USED*

*NOT USED*

6

Green / black dot

*NOT USED*

The Green wires are the 5v feeds which

7

Green / red dot

*NOT USED*

are not needed

8

Green / black dash

*NOT USED*

9

Green / red dash

*NOT USED*

10

*NOT USED*

*NOT USED*

11

Yellow / black dot

2

12

Yellow / red dot

4

13

Yellow / black dash

6

14

Yellow / red dash

8

15

Yellow / long black dash

10

16

White / black dot

12

17

White / red dot

14

18

White / black dash

16

19

White / red dash

18

20

*NOT USED*

*NOT USED*

12v DC *see notes below

From your external PSU

13, 15, 17, 19

All these can be connected together to the 12v feed

5v DC *see notes below

From your external PSU

11

Notes:

For the HDI-20 colour code, the first colour is the wire colour, the second is the marking on the wire. So 'Orange/Black Dot' means an orange wire marked with black dots.

The Superdrive wires 9 and 20 are not used

If you're using an external SCSI box or a standard PeeCee PSU, and are using power from the hard drive connectors then the red wire is the 5v and the yellow wire is the 12v. The black wires are not needed.

Once the cable is made up it's just a case of plugging it in:

Here's the drive mounted in the external case:

And the finished article!



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