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The internal floppy disk drives found in vintage Macintosh computers were manufactured by '''Sony''' and '''Mitsubishi''' and were used in models from the '''1980s to early 1990s'''. These drives came in different configurations:
The internal floppy disk drives fitted to vintage Macintosh computers are 3.5-inch
mechanisms made by '''Sony''' and '''Mitsubishi''', used from 1984 into the late 1990s. Three
generations matter:


* '''400KB''' – Single-sided, Sony 3.5" Drive (Macintosh 128K & 512K)
* '''400 KB''' – single-sided, Sony 3.5-inch ([[Macintosh 128K|128K]] and [[Macintosh 512K|512K]])
* '''800KB''' – Double-sided, Sony 3.5" Drive (Macintosh Plus, SE, etc.)
* '''800 KB''' – double-sided, Sony 3.5-inch ([[Macintosh Plus|Plus]], [[Macintosh SE|SE]] and others)
* '''1.4MB''' – High-density, Sony & Mitsubishi (later Macintosh models)
* '''1.4 MB''' – high-density Apple SuperDrive, Sony and Mitsubishi mechanisms (later models)


Over time, these drives develop issues due to '''dust buildup, old lubricants, misalignment, aging components, and mechanical wear'''. Proper '''cleaning, lubrication, and calibration''' can restore functionality and ensure long-term reliability.
They fail with age from dust, hardened grease in the eject mechanism, dried lubricant on the
carriage rails, worn or dirty heads and cracked plastic gears. Cleaning and re-greasing
recover most drives. Alignment does not — see [[#What cannot be adjusted|What cannot be
adjusted]] below.


== Disassembly and Cleaning ==
== These drives have no belt ==


=== Preparing for Maintenance ===
'''The Apple SuperDrive and its 400 KB and 800 KB predecessors are direct drive.''' The
Before working on the floppy drive:
spindle is coupled straight to a DC brushless motor; there is no belt, no pulley and no belt
* Ensure the '''Macintosh is powered off and unplugged'''.
part number.<ref name="mf355c">Mitsubishi Electric, ''MF355C 3.5-inch Diskette Drive
* Work on a static-free surface with an '''anti-static wrist strap'''.
Specifications'', UGD-0527A, February 1987: "The drive uses a DC brushless, direct-drive
* Gather appropriate tools, such as a '''Torx T15 screwdriver'''.
motor"; the disk rotation mechanism "uses a DC brushless direct-drive motor to directly
rotate the spindle". Hosted on this wiki as
[[:File:Mitsubishi MF355C 3.5 inch Diskette Drive Specifications (UGD-0527A, Feb 1987).pdf]].</ref>


To remove the floppy drive:
The word "belt" does not appear anywhere in Apple's service documentation for these drives —
# Open the case with the Torx screwdriver.
not in the ''Apple 3.5 Drive'', ''Apple 400K Drive'', ''Apple 800K Drive'', ''Apple
# Disconnect the '''ribbon cable''' and '''power connector'''.
SuperDrive'' or ''Macintosh HDI-20 1.4 MB Drive Service Source'' volumes.<ref name="ss35">Apple
# Remove mounting screws and gently slide out the drive.
Computer, Inc., ''Apple 3.5 Drive Service Source'' (Specifications, Troubleshooting, Take
[[File:FDD head.jpg|thumb|Floppy Drive Head]]
Apart). Hosted on this wiki as [[:File:Apple 3.5 drive.pdf]].</ref><ref name="sssuper">Apple
Computer, Inc., ''Apple SuperDrive Service Source'' (Troubleshooting &rarr; Symptom Charts;
Take Apart). Hosted on this wiki as [[:File:Apple superdrive.hdi 20.pdf]].</ref>


=== Cleaning the Drive Mechanism ===
'''Advice to "check the drive belt" on a Macintosh floppy drive is wrong and has propagated
* Use '''compressed air''' or a '''soft anti-static brush''' to remove dust.
from this page to several machine pages.''' Belt-driven floppy mechanisms are a 5.25-inch
* Clean rails and gears with '''isopropyl alcohol (>90%) and lint-free cloth'''.
full-height phenomenon (Tandon TM100, CDC/MPI and similar) — see
* Gently clean the '''read/write heads''' using a cotton swab dipped in alcohol.
[[Floppy Drive Repair]].
* Inspect the felt pressure pad (if present) for wear or displacement.


== Re-Tensioning the Floppy Drive Heads ==
== Specifications you can measure against ==


Over time, the tension spring or pressure pad that presses the floppy disk against the read/write head can weaken, resulting in intermittent or failed reads, write errors, or disk ejection issues. Re-tensioning ensures the floppy head maintains adequate contact with the disk surface.
Apple publishes a real specification for the 800 KB Apple 3.5 Drive, and it converts directly
into bench checks.<ref name="ss35" />


=== When to Perform Re-Tensioning ===
<templatestyles src="Template:StyledTable/styles.css" />
Consider re-tensioning if:
{| class="wikitable styled-table"
* Disks fail to mount despite clean heads.
|+ Apple 3.5 Drive (800 KB)
* You observe '''intermittent reads or write errors''' across multiple known-good disks.
! Parameter !! Apple's figure
* The head appears to sit loosely or fails to exert pressure on the disk surface.
|-
| Tracks per inch || 80
|-
| Recording surfaces || 2
|-
| Seek time, track to track || 6 ms maximum
|-
| Settle time || 30 ms maximum
|-
| Drive start-up time || 600 ms maximum
|-
| Head position accuracy || ±0.035 mm
|-
| Formatted capacity || 800 K (certified double-sided media)
|-
| Unformatted capacity || 1,246 K
|-
| Operating temperature || 5–50 °C (40–122 °F)
|-
| Relative humidity || 5–90%, no condensation
|}


=== Identifying the Pressure Mechanism ===
{| class="wikitable styled-table"
Depending on the floppy drive model (Sony, Mitsubishi, Alps), the pressure mechanism may consist of:
|+ Apple 3.5 Drive — current draw
* A '''spring-loaded upper pressure pad'''
! Rail !! Standby !! Typical !! Peak
* A '''pivoted pressure arm'''
|-
* In some drives, a '''felt pad''' or '''metal tension spring''' on the head assembly
| +12 V || 10 µA || 120 mA || 600 mA, during eject only, 2 seconds maximum
|-
| +5 V || 10 mA || 360 mA || —
|}


Locate the '''upper head assembly''' and observe how it presses the disk against the lower head.
A drive that pulls far more than this, or that drags a rail down when it spins up, has a
shorted motor driver or a seized mechanism. A drive that pulls nothing at all is not being
powered — check the cable before opening the drive.


=== Re-Tensioning Procedure ===
== Disassembly and cleaning ==
# '''Disassemble the drive''' following the cleaning steps above.
# Identify the '''pressure spring''' or tension arm on the upper head assembly.
# If the spring has slack:
## Gently bend or re-arch the spring to apply more downward pressure.
## If using a coiled spring, stretch it slightly to restore force.
# If the drive uses a '''felt pad''', ensure it is not compressed flat. Replace it with similarly sized felt material if worn.
# Reassemble the drive and insert a known-good floppy disk.
# Run a read/write test to confirm consistent operation.


=== Important Notes ===
=== Before you start ===
* Avoid '''over-tensioning''' — excessive pressure can damage the magnetic coating on disks or wear out the heads prematurely.
* Power off and unplug the Macintosh.
* Always verify drive alignment after performing mechanical adjustments.
* Work on a static-free surface with an anti-static wrist strap.
* Most compact Macintosh cases need a '''Torx T15''' driver (a long-shaft one for the case screws inside the handle well).


=== Additional Testing ===
To remove the drive:
You can use disk utilities such as:
# Open the case.
* '''Apple HD SC Setup''' (for formatting and writing)
# Disconnect the ribbon cable and, on drives that have one, the power connector.
* '''Disk Copy 4.2''' (for verifying readable sectors)
# Remove the mounting screws and slide the drive out.


== Drive Alignment and Calibration ==
[[File:FDD head.jpg|thumb|Floppy drive head]]


=== Track Zero Sensor Alignment ===
=== Cleaning the mechanism ===
If the drive clicks repeatedly or fails to detect disks:
* Blow the dust out with compressed air, or lift it with a soft anti-static brush.
* Locate the optical sensor near the head carriage.
* Clean the carriage rails and gears with isopropyl alcohol (>90%) and a lint-free cloth.
* Loosen its mounting screws.
* Clean the read/write heads with a cotton bud dipped in isopropyl alcohol, moving along the head rather than across it. Support the upper head arm — do not let it snap down onto the lower head.
* Insert a good floppy disk and adjust the sensor slightly.
* Apple's own first remedy for "drive is unable to read; many file transfer errors occur" and for "drive fails to format" is, in both cases, '''clean drive'''.<ref name="sssuper" />
* Test for operation and retighten once aligned.


=== Read/Write Head Alignment ===
=== Re-greasing ===
If the drive can’t read disks from other machines:
* Re-grease the carriage rails, the eject gears and the worm drive with a '''plastic-safe synthetic grease'''. Hardened forty-year-old grease is the single most common cause of a drive that will not eject or that grinds.
* Loosen the screws on the stepper motor.
* Do not use WD-40 or any other penetrating oil: it creeps, attracts dust and degrades the plastics.
* Rotate it minutely, testing with known-good disks.
* Do not over-apply. Grease on the head or on the media path will ruin disks.
* Re-test until consistent read/write operation is achieved.


== Common Failure Points and Repairs ==
== Common failures and repairs ==


=== Eject Mechanism Issues ===
=== Eject mechanism ===
Mechanical eject systems fail due to:
Mechanical eject systems fail through:
* '''Eject motor failure'''
* Eject motor failure
* '''Old hardened grease on gears'''
* Hardened grease on the gears
* '''Cracked or broken plastic gears'''
* Cracked or broken plastic gears — the eject worm gear is a known casualty, and 3D-printed replacements are widely available
* '''Dirty eject switches'''
* Dirty eject switches
'''Fixes:'''
* Clean and reapply '''plastic-safe grease'''.
* Replace damaged gears (3D printed replacements are common).
* Inspect and clean eject switches.


=== Non-Reading Drives ===
Fixes: clean and re-grease with a plastic-safe grease, replace broken gears, clean the
If the drive does not read disks:
switches.
* Clean the '''read/write heads''' thoroughly.
* Inspect heads under magnification for damage.
* Check '''stepper and spindle motors'''.
* Verify operation of the disk insertion and write-protect sensors.


=== “Slipping” Head and Mechanical Wear ===
=== Drive will not read ===
'''Symptoms:'''
* Clean the heads thoroughly and inspect them under magnification for wear or a scored surface.
* Intermittent reading
* Check that the spindle turns freely by hand and that the stepper moves the carriage the whole way.
* Head carriage skipping or failing to track
* Verify the disk-insertion and write-protect sensors — a blocked write-protect sensor makes every disk read-only, and a blocked insertion sensor makes the drive ignore disks entirely.
'''Fixes:'''
* Try known-good media. Forty-year-old disks shed oxide, and a shedding disk will contaminate a freshly cleaned head in one pass.
* Ensure pressure springs are intact.
* Clean and lightly lubricate guide rails.
* Inspect for head misalignment.


=== Stepper Motor Failures ===
=== Drive reads but will not write ===
The stepper motor is responsible for accurate head tracking.
Apple's chart sends this straight to "verify that drive is 1.4 MB SuperDrive", then to
replacing the mechanism.<ref name="sssuper" /> In practice, check the write-protect shutter
and sensor first — that accounts for most of them.


'''Symptoms:'''
=== Stepper and carriage ===
* Symptoms: no movement, failure to seek, tracking that drifts.
* Clean and lightly lubricate the guide rails; check the stepper coil continuity with a multimeter.
* A stepper that buzzes without moving is usually mechanically jammed rather than electrically dead.


* No movement
== What cannot be adjusted ==
* Seeking failure
* Track misalignment
'''Fixes:'''
* Apply a small amount of synthetic oil to bearings.
* Use a multimeter to test motor coil continuity.
* Replace with a donor motor if needed.


== Lubrication and Long-Term Maintenance ==
Three procedures circulate for these drives: '''re-tensioning the head spring''', '''aligning
To preserve drive functionality:
the track-zero sensor''' by loosening its screws, and '''aligning the heads''' by loosening
* Lubricate drive rails, gears, and stepper motor with '''plastic-safe synthetic grease'''.
the stepper motor and rotating it. None of them is in Apple's documentation, and all three
* Avoid household lubricants like '''WD-40''' — they degrade over time and attract dust.
are wrong for these mechanisms:
 
* '''There is no felt pressure pad in a double-sided 3.5-inch drive.''' The felt pad belongs to single-sided 5.25-inch drives. A Sony or Mitsubishi 3.5-inch mechanism has an upper head on a sprung gimbal that loads against the lower head, and bending that spring changes the head load force away from the manufacturer's figure — which is not recoverable without the manufacturer's jig.
* '''Head alignment on these drives needs an alignment disk and an oscilloscope''', not trial and error against known-good disks. Moving the stepper by hand destroys the drive's compatibility with every disk written elsewhere, including the ones that used to work.
* Apple's own service documentation contains '''no adjustment procedure of any kind''' for these drives. Every symptom in the ''Apple SuperDrive'' and ''Apple 3.5 Drive'' charts ends in "clean drive" or "replace drive mechanism".<ref name="sssuper" /><ref name="ss35" />
 
If a cleaned, re-greased drive still misreads disks from other machines, the realistic
options are a known-good donor mechanism or a modern replacement, not an alignment attempt.
 
== Things that are not faults ==
 
* '''A disk formatted on a 1.4 MB SuperDrive that a PC will not read.''' Apple's answer is to format all disks on the MS-DOS drive first, and then both drives can read and write them.<ref name="sssuper" />
* '''A SuperDrive that reads 800 K disks but not high-density ones.''' Check it really is a 1.4 MB SuperDrive and not an 800 K mechanism in a later machine; Apple's chart asks this first.<ref name="sssuper" />
* '''A single click on insertion.''' That is the mechanism clamping the hub, and it is normal.
 
== Testing ==
 
* '''Disk Copy''' verifies that a disk reads end to end and is the quickest way to prove a repair.
* A known-good disk written on a '''different''' machine is the only test that distinguishes a dirty head from an alignment problem.
* ''Apple HD SC Setup'' is a '''hard disk''' utility and has no role in floppy testing, despite being listed as one in several places.
 
== Apple's own drive manuals on this wiki ==
 
* '''[[Macintosh HDI-20 1.4 MB Drive Service Source]]''' — the HDI-20 external drive, 18 pages,
  '''Troubleshooting and Take Apart only'''. Apple printed no specifications chapter for it at all,
  so there is no capacity, data rate or current figure in it; what it does carry is the removal of
  the '''cable interface board''' and the HDI-20 external cable.
* '''[[Service Support Tranning Programs Laserwriter Technical Procedures Jan 1985]]''' — contains
  Apple's DuoDisk and UniDisk technical procedures, with the '''DuoDisk chip-swapping chart''' and
  both illustrated parts lists.<ref name="lwtp85">Apple Computer, ''Apple LaserWriter Printer Technical Procedures'', preliminary version for internal use only, sections stamped rev. Jan 85 and rev. Feb 85. Held on this wiki inside the Service Support Training Programs binder scan, described at [[Service Support Tranning Programs Laserwriter Technical Procedures Jan 1985]] ([[:File:Service_Support_Tranning_Programs_Laserwriter_Technical_Procedures_Jan_1985.pdf]]).</ref>
* '''[[Macintosh II Repair and Upgrade Secrets]]''' — Larry Pina's chapter 8 covers 400K, 800K and
  1.4 MB drives, formatting rules, building an external drive adapter, fitting a second internal
  drive, the FDHD/ROM upgrade and 800K drive troubleshooting. Secondary source.
* [[Apple 3.5 Drive Service Source]] - the only Apple external floppy volume with a full Specifications chapter, and therefore the source for the 800K mechanism's seek, settle, startup and current figures.
* [[Apple SuperDrive/HDI-20 Service Source]] - the symptom chart for the external 1.4 MB drive.<ref name="sssuperfdm">''Apple SuperDrive'', Apple ''Service Source'', 21 pages - hosted on this wiki as [[Apple SuperDrive/HDI-20 Service Source]]. Its symptom chart is the only one Apple published for an external Apple floppy drive, and it records two normal behaviours that get misdiagnosed: an MS-DOS machine will not read a disk formatted on a 1.4 MB SuperDrive unless the disk was formatted on the MS-DOS drive first, and a drive that handles 800K media but refuses high-density disks is usually an 800K drive rather than a faulty SuperDrive.</ref>
* [[Apple 400K Drive Service Source]] and [[Apple 800K Drive Service Source]] - Take Apart procedures only; the 800K volume also carries Apple's '''Restoring Mouse Eject''' procedure.
* [[Apple PC 5.25 Drive Service Source]] - the 360K 5.25-inch drive, with its 300 rpm and current figures.


== Additional Resources ==
== Additional Resources ==
Line 131: Line 180:
* [[:Category:Apple Service Source|Apple Service Source]]
* [[:Category:Apple Service Source|Apple Service Source]]
* [[Macintosh SE/30 Troubleshooting|Macintosh SE/30 Troubleshooting Guide]]
* [[Macintosh SE/30 Troubleshooting|Macintosh SE/30 Troubleshooting Guide]]
* [[Floppy Drive Repair|Floppy Drive Repair (General)]]
* [[Floppy Drive Repair|Floppy Drive Repair (general)]]
 
== References ==
<references />


{{Navbox-AppleVintage|state=collapsed}}
[[Category:Apple Vintage Computers]]
[[Category:Apple Vintage Computers]]
[[Category:Apple Maintenance Guides]]
[[Category:Apple Maintenance Guides]]
[[Category:Floppy Drive Maintenance]]

Latest revision as of 08:54, 25 September 2026

The internal floppy disk drives fitted to vintage Macintosh computers are 3.5-inch mechanisms made by Sony and Mitsubishi, used from 1984 into the late 1990s. Three generations matter:

  • 400 KB – single-sided, Sony 3.5-inch (128K and 512K)
  • 800 KB – double-sided, Sony 3.5-inch (Plus, SE and others)
  • 1.4 MB – high-density Apple SuperDrive, Sony and Mitsubishi mechanisms (later models)

They fail with age from dust, hardened grease in the eject mechanism, dried lubricant on the carriage rails, worn or dirty heads and cracked plastic gears. Cleaning and re-greasing recover most drives. Alignment does not — see What cannot be adjusted below.

These drives have no belt

[edit | edit source]

The Apple SuperDrive and its 400 KB and 800 KB predecessors are direct drive. The spindle is coupled straight to a DC brushless motor; there is no belt, no pulley and no belt part number.[1]

The word "belt" does not appear anywhere in Apple's service documentation for these drives — not in the Apple 3.5 Drive, Apple 400K Drive, Apple 800K Drive, Apple SuperDrive or Macintosh HDI-20 1.4 MB Drive Service Source volumes.[2][3]

Advice to "check the drive belt" on a Macintosh floppy drive is wrong and has propagated from this page to several machine pages. Belt-driven floppy mechanisms are a 5.25-inch full-height phenomenon (Tandon TM100, CDC/MPI and similar) — see Floppy Drive Repair.

Specifications you can measure against

[edit | edit source]

Apple publishes a real specification for the 800 KB Apple 3.5 Drive, and it converts directly into bench checks.[2]

Apple 3.5 Drive (800 KB)
Parameter Apple's figure
Tracks per inch 80
Recording surfaces 2
Seek time, track to track 6 ms maximum
Settle time 30 ms maximum
Drive start-up time 600 ms maximum
Head position accuracy ±0.035 mm
Formatted capacity 800 K (certified double-sided media)
Unformatted capacity 1,246 K
Operating temperature 5–50 °C (40–122 °F)
Relative humidity 5–90%, no condensation
Apple 3.5 Drive — current draw
Rail Standby Typical Peak
+12 V 10 µA 120 mA 600 mA, during eject only, 2 seconds maximum
+5 V 10 mA 360 mA —

A drive that pulls far more than this, or that drags a rail down when it spins up, has a shorted motor driver or a seized mechanism. A drive that pulls nothing at all is not being powered — check the cable before opening the drive.

Disassembly and cleaning

[edit | edit source]

Before you start

[edit | edit source]
  • Power off and unplug the Macintosh.
  • Work on a static-free surface with an anti-static wrist strap.
  • Most compact Macintosh cases need a Torx T15 driver (a long-shaft one for the case screws inside the handle well).

To remove the drive:

  1. Open the case.
  2. Disconnect the ribbon cable and, on drives that have one, the power connector.
  3. Remove the mounting screws and slide the drive out.
Floppy drive head

Cleaning the mechanism

[edit | edit source]
  • Blow the dust out with compressed air, or lift it with a soft anti-static brush.
  • Clean the carriage rails and gears with isopropyl alcohol (>90%) and a lint-free cloth.
  • Clean the read/write heads with a cotton bud dipped in isopropyl alcohol, moving along the head rather than across it. Support the upper head arm — do not let it snap down onto the lower head.
  • Apple's own first remedy for "drive is unable to read; many file transfer errors occur" and for "drive fails to format" is, in both cases, clean drive.[3]

Re-greasing

[edit | edit source]
  • Re-grease the carriage rails, the eject gears and the worm drive with a plastic-safe synthetic grease. Hardened forty-year-old grease is the single most common cause of a drive that will not eject or that grinds.
  • Do not use WD-40 or any other penetrating oil: it creeps, attracts dust and degrades the plastics.
  • Do not over-apply. Grease on the head or on the media path will ruin disks.

Common failures and repairs

[edit | edit source]

Eject mechanism

[edit | edit source]

Mechanical eject systems fail through:

  • Eject motor failure
  • Hardened grease on the gears
  • Cracked or broken plastic gears — the eject worm gear is a known casualty, and 3D-printed replacements are widely available
  • Dirty eject switches

Fixes: clean and re-grease with a plastic-safe grease, replace broken gears, clean the switches.

Drive will not read

[edit | edit source]
  • Clean the heads thoroughly and inspect them under magnification for wear or a scored surface.
  • Check that the spindle turns freely by hand and that the stepper moves the carriage the whole way.
  • Verify the disk-insertion and write-protect sensors — a blocked write-protect sensor makes every disk read-only, and a blocked insertion sensor makes the drive ignore disks entirely.
  • Try known-good media. Forty-year-old disks shed oxide, and a shedding disk will contaminate a freshly cleaned head in one pass.

Drive reads but will not write

[edit | edit source]

Apple's chart sends this straight to "verify that drive is 1.4 MB SuperDrive", then to replacing the mechanism.[3] In practice, check the write-protect shutter and sensor first — that accounts for most of them.

Stepper and carriage

[edit | edit source]
  • Symptoms: no movement, failure to seek, tracking that drifts.
  • Clean and lightly lubricate the guide rails; check the stepper coil continuity with a multimeter.
  • A stepper that buzzes without moving is usually mechanically jammed rather than electrically dead.

What cannot be adjusted

[edit | edit source]

Three procedures circulate for these drives: re-tensioning the head spring, aligning the track-zero sensor by loosening its screws, and aligning the heads by loosening the stepper motor and rotating it. None of them is in Apple's documentation, and all three are wrong for these mechanisms:

  • There is no felt pressure pad in a double-sided 3.5-inch drive. The felt pad belongs to single-sided 5.25-inch drives. A Sony or Mitsubishi 3.5-inch mechanism has an upper head on a sprung gimbal that loads against the lower head, and bending that spring changes the head load force away from the manufacturer's figure — which is not recoverable without the manufacturer's jig.
  • Head alignment on these drives needs an alignment disk and an oscilloscope, not trial and error against known-good disks. Moving the stepper by hand destroys the drive's compatibility with every disk written elsewhere, including the ones that used to work.
  • Apple's own service documentation contains no adjustment procedure of any kind for these drives. Every symptom in the Apple SuperDrive and Apple 3.5 Drive charts ends in "clean drive" or "replace drive mechanism".[3][2]

If a cleaned, re-greased drive still misreads disks from other machines, the realistic options are a known-good donor mechanism or a modern replacement, not an alignment attempt.

Things that are not faults

[edit | edit source]
  • A disk formatted on a 1.4 MB SuperDrive that a PC will not read. Apple's answer is to format all disks on the MS-DOS drive first, and then both drives can read and write them.[3]
  • A SuperDrive that reads 800 K disks but not high-density ones. Check it really is a 1.4 MB SuperDrive and not an 800 K mechanism in a later machine; Apple's chart asks this first.[3]
  • A single click on insertion. That is the mechanism clamping the hub, and it is normal.

Testing

[edit | edit source]
  • Disk Copy verifies that a disk reads end to end and is the quickest way to prove a repair.
  • A known-good disk written on a different machine is the only test that distinguishes a dirty head from an alignment problem.
  • Apple HD SC Setup is a hard disk utility and has no role in floppy testing, despite being listed as one in several places.

Apple's own drive manuals on this wiki

[edit | edit source]
 Troubleshooting and Take Apart only. Apple printed no specifications chapter for it at all,
 so there is no capacity, data rate or current figure in it; what it does carry is the removal of
 the cable interface board and the HDI-20 external cable.

 Apple's DuoDisk and UniDisk technical procedures, with the DuoDisk chip-swapping chart and
 both illustrated parts lists.[4]

 1.4 MB drives, formatting rules, building an external drive adapter, fitting a second internal
 drive, the FDHD/ROM upgrade and 800K drive troubleshooting. Secondary source.

Additional Resources

[edit | edit source]

References

[edit | edit source]
  1. ↑ Mitsubishi Electric, MF355C 3.5-inch Diskette Drive Specifications, UGD-0527A, February 1987: "The drive uses a DC brushless, direct-drive motor"; the disk rotation mechanism "uses a DC brushless direct-drive motor to directly rotate the spindle". Hosted on this wiki as File:Mitsubishi MF355C 3.5 inch Diskette Drive Specifications (UGD-0527A, Feb 1987).pdf.
  2. ↑ 2.0 2.1 2.2 Apple Computer, Inc., Apple 3.5 Drive Service Source (Specifications, Troubleshooting, Take Apart). Hosted on this wiki as File:Apple 3.5 drive.pdf.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Apple Computer, Inc., Apple SuperDrive Service Source (Troubleshooting → Symptom Charts; Take Apart). Hosted on this wiki as File:Apple superdrive.hdi 20.pdf.
  4. ↑ Apple Computer, Apple LaserWriter Printer Technical Procedures, preliminary version for internal use only, sections stamped rev. Jan 85 and rev. Feb 85. Held on this wiki inside the Service Support Training Programs binder scan, described at Service Support Tranning Programs Laserwriter Technical Procedures Jan 1985 (File:Service_Support_Tranning_Programs_Laserwriter_Technical_Procedures_Jan_1985.pdf).
  5. ↑ Apple SuperDrive, Apple Service Source, 21 pages - hosted on this wiki as Apple SuperDrive/HDI-20 Service Source. Its symptom chart is the only one Apple published for an external Apple floppy drive, and it records two normal behaviours that get misdiagnosed: an MS-DOS machine will not read a disk formatted on a 1.4 MB SuperDrive unless the disk was formatted on the MS-DOS drive first, and a drive that handles 800K media but refuses high-density disks is usually an 800K drive rather than a faulty SuperDrive.


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