Well, musitronics USB board is not so easy to install, despite what they say. So here is a couple of advices about how to do it.

1) What you need
Nothing more than a couple of screwdrivers (cross magnetic head).
But you'll have to turn your PA upside down, so you better set up "something" to hold it on your table.
I used a couple of cushions, and put the Pa on the side of the table, so that the bend lever is free.
Moreover, i put a white sheet over my table (you'll discover why very soon)

2) What to open first
So turn your Pa upside down and open the hard disk protection plate (the litthe rectangular black metallic plate, fixed with four screws).

Your HD is inside there, holded by four more screws to the Pa. Remove that screws and carefully extract your HD.

3) Attach the board to your HD
Now remove the flat cable attached to the HD, insert USB board in this place and connect the cable to the other side of the USB board.
This assembly is not so firm, so you better fix the USB board to the HD using a couple of screws. But Musitronics supplied screws are too long. So remember to buy two shorter screws.

4) Put the HD back in its place
Now you have to insert your HD back in its place. But I haven't been able to do that, because the hole is too little.
Moreover, the USB cable starting from the USB board should reach the back of your PA, to have the USB connector in the VIDEO INTERFACE plate.

So I decide to completely open the Pa

5) Opening the Pa
- Remove the big black screws under the keyboard;
- remove the screws inside the holes all around the edge of the Pa;
- remove the screws inside the holes all around the bottom (warning: not all holes has a screw, so you better keep track of holes and screws);
- remove the screws under the floppy disk.

Now all the screws are gone, so gently lift the bottom of the board up (it is heavy) a little, so that your HD can go back in its place, then put the bottom of the board back to its place (maybe the floppy driver will try to obstacle you a little).

Now you can fix your HD using the 4 screws you previously removed.

6) And the USB cable?
Gently unplug the cable from little plate supplied by Musitronics, and push the cable inside your Pa a little.

Then turn your Pa on its feet again.

If your screwdriver's head is not magnetic (like mine was), all the screws will fall now, but they will all be over the white sheet.

Remove the little Video Interface metallic plate from the rear of your Pa, and free the ground cable from it.

Now firmly hold Pa's top panel, lift it up a little until you feel that it is free and turn it around its rear side.

Some cable will stop the top panel movement, so do not turn it too much. You better ask someone for help: he/she should simply hold the top panel while you find the USB cable head and move it to the hole you've made removing the Video Interface plate.

When you are done connect the power and turn the Pa on. Can you hear your HD spin noise? If not the cable is unproperly plugged to the USB board, so turn the power off, disconnect the main power cable, disconnect the HD cable from the USB board, turn the cable upside down and connect it again. Turn the Pa on again and the HD should run fine.

Now you can close the Pa .

7) Closing your Pa
Well, nothing so hard: put the top panel back in its place, gently turn your Pa upside down again and put all the screws in their places. And, of course, put the black metallic plate over the HD again and fix it with its 4 screws.

8) Last operations
Turn your Pa back on its feet and go to its rear: you should have two cable coming out the Video Interface hole: the USB cable and the ground cable.

Take the Musitronics little metallic plate from wich you unplugged the USB cable, remove one of the four screws that holds the plug to the plate, insert the ground cable and put the screw back in, so that ground connection is on its place.
Now gently plug the USB cable in its place, put the metallic plate on its place and fix it with two screws.


9) You're done
Musitronics USB board is installed, and your Pa is shining as usual.

P.S.: Software installation notes will follow...