Superdrive repair

[mnementh@netcom.com (David R. Villegas)]

I found the following article on comp.sys.mac.hardware and am reposting it
here with the author's permission:

===cut here===

MACINTOSH FLOPPY DRIVE REPAIR
(c) 1994 Peter Zelchenko (pete@chinet.com)

The Apple SuperDrive, based on Sony's MFD-75W mechanism, is specialized 
in that it can read and write 400K and 800K disks as well as 1.44 MB 
floppies.  The drive itself is available only from Apple (Sony will sell 
you neither the drive nor its components because they are under contract 
with Apple).  Apple, of course, will not sell components for the drive. 
If there is so much as a speck of dust in the wrong place, your Value 
Added Reseller will charge nearly $300 to replace the drive.  Compared to 
the PC world, where you can install a brand-new drive for as low as $30, 
this is clearly highway robbery, even taking into account the uniqueness 
of the drive.  Apple's stand on this is that they don't produce the 
SuperDrive in enough volume to sell it for a reasonable price.  Pshyeah.

Most Macintosh repair places, short of blowing the dust out of the 
drive, will prescribe a brand-new replacement drive (Apple sends the 
discards back to Sony where they refurbish them for a few dollars apiece 
so that Apple can turn them around again at an obscene profit).  There 
are a few Apple vendors, including TekServe in New York (see below for 
company information), who for a small savings will swap your drive for a 
refurbished one rather than a new one.  CJS Systems in Berkeley will also 
replace with refurbished drives.

DRIVE REPAIR.  The only other alternatives are either to repair the drive 
yourself or to send the drive directly to a repair shop.  There are very 
few places which actually repair the 75W.  Some of these, MicroDoc in 
Oregon, ERC in Pleasanton, CA, and Helix Magnetics in San Diego, are Sony 
authorized and will repair your drive for somewhere around $100, more or 
less, depending on whether it only needs adjustment or needs further 
repairs.  Mike Kass, in California, will clean and align your drives for 
an amazingly low $40 apiece, more if they need parts.  You might also try 
800-WEFIXMACS.

DO-IT-YOURSELF REPAIR.  The next level of detail, and potential savings, 
is to do the work yourself.  If you are not a tinkerer, and don't know 
your way around computer hardware, this would not be advisable.  Larry 
Pina's book, _Macintosh Repair and Upgrade Secrets_, has a section which 
describes, step-by-step, how to adjust your drive mechanics using the 
Finder's disk commands.  This takes a lot of patience, and the Finder, in 
the true Macintosh Way, is not very detailed in its feedback.  But it can 
be done, and if you had a lot of spare time you could even get pretty 
good at it.

A better solution, assuming you will be doing more than a couple of 
drives, is MacDriveProbe, from Accurite Technologies, Inc.  MacDriveProbe 
will help diagnose problems and tune the drive, with the turn of a screw 
here and a motor there.  Accurite does _not_ describe alignment 
technique; for that look to Pina's book.  For a higher price, you can buy 
a board from Accurite which gives you more detailed output from the 
drive.  They also make a PC product which can do Macintosh drives.  
MacDriveProbe's software uses lower-level calls to the Disk Manager, so 
you can use as your test stand any Macintosh which supports 1.44 MB 
disks.  Accurite includes a special digital alignment disk with its 
products, with alignment data laid down onto the tracks.  They also sell 
an analog alignment disk which, in conjunction with an oscilloscope, can 
easily be used to perform "cat's eye" track alignment.  If the problem 
goes beyond simple alignment issues, you may need to take the drive apart.

Most hardware problems develop from dust accumulation and from improper 
disk insertion.  The most common problems with drive hardware are head 
failure and, on the SuperDrive, ejector motor problems.  The ejector 
motor can be removed and overhauled without too much trouble.  If disks 
are not inserting "smartly" (with that distinctive click), are not being 
sensed by the Macintosh on insertion, and are not ejecting, it is 
probably due to the ejector motor being out of phase.  Sometimes this can 
be fixed by removing the motor and forcing it manually into phase (this 
takes a lot of pressure).  However, the phase problem is usually caused by 
problems with the motor stop switch, which requires overhaul of the small 
motor assembly.

While the drive is apart, it is a good time for a thorough cleaning.  It 
is possible to do a reasonable cleaning job without removing parts, but a 
full overhaul is not difficult (it will, however, require realigning the 
drive).  (This is not a detailed descripion -- there is no substitute for 
trying it yourself.)  Remove the disk carriage assembly, the drive head, 
the drive stepper motor, and the ejector motor, and clean all carefully.  
Use a toothbrush to remove old grease.  Open the ejector motor, remove 
and clean all parts, then reassemble and apply a tiny bit of light oil to 
the motor.  Be sure you phase the motor before reinserting, and be sure 
the switch contacts are clean and in place for the cam to open the switch 
properly.

Reassemble all parts, applying a modest coating of light grease to the 
stepper gear and to friction points on the carriage mechanism.  Test the 
mechanism, then attach and realign the drive.

HEAD REPLACEMENT.  If the drive refuses to align and subsequently read 
and write disks, the drive head mechanism may need replacement.  These 
are not at all cheap, since Apple and Sony have a monopoly on them.  
(Mike Kass tells me there is even an MFD-73W drive by Sony with the 
identical head, but Sony's price shot up from $50 to about $80 for them, 
ostensibly when they discovered Macintosh users were buying them for the 
75W.)  You can test head integrity with an oscilloscope on the RFA and RFB 
contacts of the controller board, reading a value of about 250 mV.  If 
the reading is 100 mV or less, the head must be replaced.

If head pressure is insufficient, disks will read fine until they get 
into the higher tracks (late in a copy).  According to Mike Kass, head 
pressure should be between 15 gm and 20 gm and can be adjusted by moving 
the small spring to the next higher tooth.  The Specialized tool catalog 
carries 0-35 gm tension gauges which should measure this.

You cannot buy new heads from Sony for the MFD-75W.  However, you can 
try to buy the MFD-73W head which is identical.  ERC and, I believe, 
MicroDoc, and possibly Hi-Lo Density, may sell new or refurbished heads.  
Mike Kass has the best deal yet:  He will sell refurbished heads for $65 
apiece, which he gets from his suppliers.

In a related area, Mike Kass referred me to a place in Valencia, CA, 
called Valtron, which will repair SyQuest mechanisms.  Valtron will 
repair a 44 MB SyQuest mechanism for $175 (volume pricing is available).  
So far, they say they haven't seen many 88's and no 200's, so 44's are their 
specialty.  (But I should mention that, as of this writing, 44's are 
going for $200 apiece at MacWarehouse, so why pay $175 to repair one?  He 
will need to lower his prices soon for 44's.)

Special thanks to Mike Kass (see below), who added significantly to this 
report.

Accurite         |   E|  San Jose, CA    408-433-1980
CJS Systems      | R  |  Berkeley, CA    510-849-3730  sgs@well.sf.ca.us
ERC              |D   |  Pleasanton, CA  510-416-1113
Helix Magnetics  |  P |  San Diego       619-566-8335
Hi-Lo Density    |  P |  Ventura, CA     805-642-5888
Mike Kass        |D P |  Valencia, CA    805-254-3384
MicroDoc         |DR  |  Oregon          503-344-5335
Sony Corp.       |  P |                  408-955-4747
Specialized      |   E|                  Unknown
TekServe         | R  |  New York        212-929-3645  dlerner@well.sf.ca.us
Valtron          |D   |  Valencia, CA    805-254-3384  SyQuest drives only
We Fix Macs      | R  |                  800-WEFIXMACS

D  Macintosh drive repair services (possibly refurbished drives)
R  General Macintosh repair services
P  Parts for Macintosh drives (possibly drive heads)
E  Testing equipment for Macintosh drives

-- 

Peter Zelchenko (pete@chinet.com)  |  InfoComm Electronic Pre-Press
Chicago, Illinois                  |  312-751-1220 (w), 312-RED-BIRD (h)