Inside The Sharp MD-MS200

Duncan Chisholm (y6jb8@unb.ca)

[See also Duncan's investigation of the MS200's remote]

I've always had an interest in how things work, in fact I don't think I own a single electronic device that I haven't opened up to see what's inside.  I was a little apprehensive about opening up my new minidisk recorder because it was such an expensive little piece of equipment (not that that's stopped me before) and since I ordered it from Japan I had no warranty or any easy way to have it repaired.  Only once has my curiosity about the workings of electronic devices gotten me into trouble (an unfortunate encounter with an Autohelm), but I was wary just the same.  I was pleasantly surprised when I finally decided to take my recorder apart.  The MS200 is one of the easiest devices to take apart I've seen, and one of the most rewarding for interesting things to see.
 

The Pictures

To save you a little download time, I haven't put the pictures directly on this page but provided links to them instead.  If you happen to have a nice fast internet connection you can view all the pictures on a separate page.  If viewed on a 1024x768 15" display, these pictures are approximately life-size.  They're not the greatest quality since I made them by directly scanning the MS200, so you may also want to check out some bigger scans of the outside of the MS200 (also directly scanned) on Conrad Sanderson's MS200 page.

Top Open

    The picture of the open top is the most interesting.  Note the delicate little write head in the middle.  Yes, it really is only held in place by ONE tiny little screw!  I don't think it's alignment is nearly as important as that of the optical head however, since the laser maintains lateral accuracy (it's only heating a very narrow track), and the linear accuracy is mostly dependent on how fast the disk is spinning.  I think the write head only has to be roughly aligned with the optical head so that the magnetic field emitted from it is strong enough at the point that the laser is heating.  That being said, I still think it looks like a pretty flimsy mount.  The slot-in transport mechanism, on the other hand, looks very sturdy.  It seems to be built as solidly as the ones in minidisk decks that I've seen.  It doesn't look as pretty as the hardware in Sony portables, but it does look more durable to me, and you don't normally have to look at it anyway. Of course, the disadvantage of this type of construction is that it's heavier and takes up more space.  The control buttons look pretty cheesy, but they work well, and would be exceptionally easy to repair if they ever wear out.

Bottom Open

    There's not much to say about the picture of the open bottom, except to mention one little item that really mystifies me.  I haven't been able to figure out yet why the lead from the positive terminal of the battery has it's own little sliver of circuit board going around the hole that's cut out for part of the slot-in mechanism.  Was the board so tightly packed that they couldn't find any room for the power trace, or did they just forget about it until the last minute?  If the positive end of the battery had to be connected to that specific spot and there was no room left on the board, why didn't they just use a slightly longer piece of wire to get it there, instead of that vulnerable-looking sliver of PCB?  I guess a wire might potentially get too close to the parts of the loading mechanism and have it's insulation worn of.
 
 

Opening Up Your MS200

    If you're crazy enough to consider trying this out for yourself, here are a few points to remember:  
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