Floppy Disk Drives. .
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Floppy Disk Drives.
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001- How do I add a write-protect On-Off switch?
002- How do I add external speed adjustment to
my Disk ][ drive?
003- How can I adjust my 5.25" drive for optimum
performance?
004- How do I clean my disk drive R/W head(s)?
005- What is the pinout for a duodisk drive connecting
cable?
006- What DuoDisk mods are necessary?
007- Will a Duodisk function correctly on my ROM
3 GS?
008- How do I fix a false Write Protect?
009- My 3.5 Disk Drives don't work! What should
I try?
010- I added SCSI; now, my 3.5" drives often fail
to work. Why?
011- Both of my Disk ]['s come on when booting!
Is there a fix?
012- In connecting a Disk II I misaligned the
connectors. A fix?
013- A sound like a shotgun going off came from
my drive. A fix?
014- Uni-disk and Laser drives: neither works
with my IIc. Why?
015- How do I replace a 3.5" drive mechanism with
one from a Mac?
016- I have one 5.25" drive. Sys6 shows two icons!?
Is there a fix?
017- How can I tell a 13 from a 16-sector Disk
][ controller card?
018- Can a Disk ][ Drive be used on a IIc or GS
smartport?
019- How do I install a bi-color LED R/W indicator
in my Disk ][?
020- What's the scoop on the 3.5" High Density
drive?
021- What is a "UniDisk"?
022- What is a "RAM disk"; and, how do I create
one on my IIgs?
023- Which 3.5" drive/interface combinations work
on a IIe?
024- How can I boot from my /RAM5 RAM disk?
025- My 5.25" drive ruins every disk I insert.
How can I fix it?
026- Incorrect 'Disk Full' error on a 3.5" UniDisk
drive. Why?
001- How do I add a write-protect On-Off switch
to my Disk ][ drive?
Adding an Auto/Manual Write-Protect Switch
Often, as when doing copying, it is useful
to be able to guarantee that a
diskette is Write-Protected whether or not the side is notched. Other
times, it
is convenient to defeat Write Protection-- for example, when you wish
to write
to a diskette side which is not notched. And, naturally, you also want
a
setting which permits Normal, notch-controlled, Write-Protect.
Based upon a circuit suggested by David Wilson
(Australia), the A/MWP
enhancement offers full user control of Write Protect. The switch's
three
positions are
Protect OFF: Writing is allowed regardless of notching.
Protect ON: Writing is prohibited regardless of notching.
Normal: a diskette side must be notched to permit writing.
A/MWP Step-by-Step
Unplug the drive from the disk controller and remove the case.
Drill a mounting hole. This can be at a convenient spot in the back
or in the
plastic front panel. On the front, a good spot is at the lower left,
above and
to the left of the "in use" LED. Another open spot is at the upper
right in the
space just above the diskette slot; but, we're saving this place for
Part 2's
enhancement. (You can't use the lower right, of course, because this
would mess
up the "Apple" logo!)
Cut three wires (Brown, Black, and White) long enough to run from the
mounting
point to the Large Connector plugged onto the back, middle of the Disk
][
circuit board.
Solder the leads to a Single-Pole Triple-Throw mini toggle Switch:
Brown to
center, White to one end, Black to other end. Twist the leads or encase
them in
tubing.
Mount the Switch. Normally, the Switch handle will point in the White
lead
direction for "Protect OFF" and in the Black lead direction for "Normal".
Center is "Protect ON". Route the leads to the area next to the Large
Connector. (Make sure no wires will get in the way of an inserted diskette.)
Locate the Brown and Black leads coming from the Notch Detect micro-switch.
The
leads are the Brown (bottom) and Black (top) pair near the right end
of the
Large Connector (as viewed from the front of the drive).
Cut the Notch Detect micro-switch leads about 1" away from the Large Connector.
Connect the Black Notch Detect, Black Large Connector, and Black Switch
leads
(i.e. strip ends, solder, and cover in heat-shrink tubing or tape).
Connect the Brown Notch Detect lead to the White Switch lead.
Connect the Brown Large Connector lead to the Brown Switch lead.
Viola! Now you're ready to replace the cover,
plug in the drive, and try
out your A/MWP enhanced Disk ][.
Boot a diskette which is not write-protected
and load a program, say the
HELLO program (or STARTUP on a ProDOS diskette). Set the A/MWP to center
and
try SAVE HELLO. You should get a "WRITE PROTECTED" error.
Place a write-protect tab on the diskette.
Set A/MWP to the Left or UP
position and try SAVE HELLO again. If the save works, then Left or
UP is the
"Protect OFF" position and Right or Down is "Normal". If you get a
"WRITE
PROTECTED" error then it's the other way around.
Now is a good time to mark "Normal" and, if
you like, the other positions.
You can use dots punched from self-stick labels.
From: Ed Eastman
Most of the time what you want to be able to
do with a Write Protect modification
is turn On Write Enable when a disk is not notched. That is what this
mod for does.
Details relate to the 5.25" UniDisk but the method will also
work with other Apple II
5.25" drives.
The way the write protect sensor works on newer
drives is that an LED on one side
shines on a phototransistor (the sensor) on the other side. When there
is a notch in the
diskette you insert, light passes through the gap and the sensor 'closes'
to complete the
Write Enable circuit.
What we will do is give the Write Enable circuit
an alternate enable option using an
On/Off switch. A mini toggle switch is okay; but, I like to use a small
normally-open
momentary contact pushbutton switch from Radio Shack. It's compact,
looks nice,
and pressing the button for the few seconds usually required for a
file, etc. write is
no problem.
I normally mount the switch in the upper left
part of the face plate, opposite the
light to balance the look. Drill a hole a little smaller than required
and use scissors or
a larger drill to taper the hold to just where you can screw in the
switch.
Before soldering on leads and mounting the
switch, decide where you want to
make the connections. You can locate the output leads from the sensor
and splice
one switch lead to each; or, you can find the place on the circuit
board where the
sensor leads go and connect there.
On a UniDisk you will see a large connector
labeled "CN1" near the front.
Pins 9 and 11 of CN1 are the write protect sensor connections. More
convenient
connection points are the circuit board edge side of R12 and the wire
at J29.
Solder on leads long enough to reach the connection
points and screw in the
switch. On a UniDisk, connect one switch lead to the R12 point near
the edge and
one to the wire at J29.
Now when you need to override write protect
on an unnotched disk, you simply
press the button while writing. Go ahead and plug in the drive and
give it a try.
Note: For more details, pics, and info about a three-position
switch option, see my page
at http://www.applelinc.org/UnidiskMod/UnidiskWPMod.htm.
002- How do I add an external speed adjustment to my Disk ][?
Reference: FAQs Resource file R006SPDKNOB.GIF
Adding a Speed Control Knob to your Disk ][ Drive
This article tells how to move speed adjustment
from the Disk ]['s dark
interior to a handy front-panel location and how to "tune" the
drive for
optimal performance.
One drive-test software vendor states that
Disk ][ is good for about 500
hours of normal use between speed adjustments-- not exactly a strong
argument
for placing the control on the front panel! On the other hand many
of today's
Disk ][ owners are interested in applications which go beyond "normal
use".
Some utilities (e.g. DiversiCopy II) report
rotational speed during
ongoing applications; so, relocating the speed adjuster to the front
panel is
especially helpful. Similarly, users who want to back up their old,
copy-protected wares know that ready access to speed control is essential.
Finally, there is no question that, whatever
your applications, periodic
speed trimming will be required. When it is, you'll be very glad _your_
Disk ][
has a front panel Speed Knob!
Adding Speed Knob
To install Speed Knob you will need a good
quality, linear taper 5k Ohm
potentiometer, some wires, and a knob with a pointer mark or some other
way to
show position (e.g. a ring of numbers). Most of the work, really,
consists of
opening the drive and drilling a hole. There is no need to disconnect
the drive
from the controller card.
1. Remove the 4 bottom bolts and slip off the case. Unscrew the 4 bottom
bolts
holding the drive to the case bottom, and unplug the main ribbon cable.
The
drive can now be moved to your work area.
2. Drill a hole properly sized and centered for mounting your 5k Ohm
pot in the
upper right front panel.
3. Place the drive on its face and unscrew the 2 bolts which hold the
small
daughter board to the drive. (Be ready to catch loose spacers, washers,
etc..)
4. Turn the small board over to the bottom side. Locate and cut the
traces
going to the mini-pot speed adjuster as shown in pic R006SPDKNOB.GIF.
5. Cut three wires, White, Gray, Black, long enough to reach from the
board to
the front panel. Connect these to your 5k Ohm pot and to the small
circuit
board as shown in pic R006SPDKNOB.GIF. (In case you cannot view the
pic, what
you're doing is substituting the new pot for the mini-pot. )
6. Re-mount the daughter board. Mount the 5k Ohm pot. Install knob.
7. Bring the drive back to the computer. Slide it onto the case bottom
plate,
reconnect main ribbon cable, replace bottom bolts, slide on and re-fasten
case
top.
You can use Copy II Plus, XPS, APEX, or one
of several other utilities to
set speed (see next question). A good starting adjustment will be near
the
center of Speed Knob's range. Once speed is adjusted, you can loosen
and re-set
the knob so that its position indicates a "correct" speed setting.
003- How can I adjust my 5.25" drive for the best performance?
The typical 5.25" drive will run for months
with no need for maintenance
save an occassional dusting or session with a head-cleaner disk. When
adjustment is required, it will usually be to fine-tune Speed or, less
often,
to set track centering.
If a 5.25" drive has difficuly reading diskettes,
including those it
created, and head-cleaning does not help, then, the odds are it's time
to
adjust speed. If your drive is a Disk ][ and does not have the external
'Speed
Knob' mod, look for a small hole on the lower right side near the back--
some
owners add this hole to allow easy access to the Speed Adjustment mini-pot
screw. If there is no hole, you will need to remove the case. (Remove
bolts on
bottom and slide out the drive through the front.)
On the 5.25" Apple 'Platinum Drive', the Speed
Adjustment is accessed
through a small hole on the bottom of the drive near the front on the
right
side. Non-Apple 5.25" drives may place the Speed Adjustment almost
anywhere.
Look for a small hole through which you can see a screw head. If you
don't fine
one, remove the case and look for a mini-pot labeled "Speed" or something
similar.
The most popular speed adjustment software
utility is, probably, dear old
Copy II Plus. From the menu, just select "Verify", then "Drive Speed".
Put a
diskette into the drive you want to adjust and, turning the Speed Knob
(or
min-pot shaft) use Copy II's numeric speed display to zero-in on the
'magic'
200ms. number. (Standard Disk ][ rotation speed is 300 rpm, which comes
out to
be 0.2 seconds per revolution.)
Other speed adjustment utilities show an rpm
number or a hires pointer.
Whatever, all speed check routines need to read AND write; so, you
will usually
need a "scratch diskette" which you do not mind having over-written.
Track-center realignment is needed when a Disk
][ writes and reads its own
disks fine, but does not 'communicate' with many other Apple II 5.25"
drives.
It generates disk errors when reading disks written by other drives
and other
drives have the same problem with its diskettes.
CALL A.P.P.L.E's
APTEST, now in the public domain, tests track-center
alignment. With this software, the user checks the alignment
of the drive with
disks regarded as well aligned --- such as Apple diskware supplied
with the
computer or some unprotected, original, commercial software diskette.
(In a
pinch, a diskette formatted by any drive that has no problem reading
most other
diskettes should be okay.)
Basically, a track-centering test tries to
step your head between two
tracks of the 'standard' diskette and read the tracks on either side.
If the
number of successful reads from each track is about equal, the head
is
"centered" and your drive is well-aligned with the standard diskette.
The test may indicate serious misalignment.
("Aha! That explains why my
IIgs and II+ have problems reading each other's diskettes!")
Centering
adjustment is done by slightly repositioning the stepper motor (mounted
on the
underside of the drive). This requires loosening the two bolts holding
the
stepper-motor, rotating it clockwise or counter-clockwise, and retightening.
The adjustment/test process may require several
repetitions. Each time,
the program will report "differential fractions". The smaller these
numbers,
the closer you are to near perfect alignment with tracks on the diskette.
From: Rubywand
Suppose you have just
one drive and it is so far out of adjustment that it will
not boot a speed adjustment utility diskette?
In this case, you can remove the drive
cover, turn over the drive, and (probably) find that the drive has
a strobe pattern
on the main pulley or flywheel.
Set a fluorescent light near the drive (or
do the adjustment in a room with
fluorescent lighting). Get the drive spinning via power-on booting
or a PR#6 and
adjust the speed for a stable pattern.
Note: If you live in a place which supplies 50Hz power and the drive
is intended
for use in the U.S. or other country with 60Hz power, you may have
to experiment
with + deviations in speed from a stable pattern.
004- How do I clean my disk drive R/W head(s)?
The easiest way to clean a drive's R/W head(s)
is with a Cleaner Diskette.
This is a diskette with a paper disk such as the 5.25" and 3.5" Cleaner
Diskettes available in Radio Shack's Disk Drive Head Cleaner Kits.
These kits
usually include "Cleaning Fluid" (isopropyl alcohol), too.
The 5.25" Cleaner Diskette has panels you pop
out to expose the cleaning
surface. Apple II 5.25" drives have a single head which contacts the
disk from
the bottom and a pressure pad which presses against the top side. So,
pop out
the panel on the bottom side of the Cleaner Diskette and leave the
top panel in
place. When cleaning, insert the diskette with the bottom side facing
down.
This lets the paper disk rub against the head and avoids wear on the
pressure
pad.
The 3.5" diskette has a small plastic panel
you can snap out for cleaning
two-head drives. Since the standard 3.5" 800k Apple II drive has two
heads,
snap out the panel so that both the top and bottom heads get wiped.
To clean your drive head(s), you sqirt a few
drops of Cleaning Fluid onto
the Cleaner Diskette disk, insert it into the drive, and get the disk
spinning.
Allow about 20 seconds for a 5.25" and a couple10-second spins, with
drops
between spins, for a 3.5" drive. (Booting the Cleaner Diskette is one
way to get
it spinning. If DOS or ProDOS is installed, doing a CATALOG is another
way.
For example: CATALOG,S6,D2 would get your 5.25" Drive 2 spinning.
Doing a RESET will stop the spinning.)
If you think it has been several months since
the drive was last cleaned,
repeat the procedure-- i.e remove the Cleaner Diskette, add more fluid,
etc..
As a rule, do not let the disk spin more than 15-20 seconds for any
cleaning
cycle. This is especially a concern with 3.5" drives where the heads
are
mounted on springs and much more subject to snagging and being pulled
out of
alignment.
005- I picked up an apple IIe and a duodisk drive at a thrift
store. Could someone describe the connecting
cable?
I just checked the pinout on a Duodisk cable.
The numbers for the pins
are inside the plug by the pins, but I'll draw them for you.
DB 19 looking at the end of the cable:
1 2 3 4
5 6 7 8 9 10
o o o o
o o o o o o
o o o
o o o o o o
11 12 13 14
15 16 17 18 19
DB 25 looking at the end of the cable: (x = no pin)
1 2 3
4 5 6 7 8 9
10 11 12 13
x o o
o o o o o o
o o o x
o o
o o o o o o
x o o x
14 15 16
17 18 19 20 21 22 23 24
25
Cable
DB 19 DB 25
1 2
2 4
3 9 & 21
4 10 & 14
5 23
6 7
7 19
8 20
9 8
10 12
11 15
12 16
13 17
14 18
15 5
16 24
17 11
18 3
19 6
From: Steve Jensen and Jonathan Adams
006- What DuoDisk mods are necessary?
The following is excerpted from an info file from my old bbs ...
There are TWO modifications that should be made to Duodisk drives:
The First one was recommended by Apple several
ago to solve occasional
problems with trashing diskettes. The solution is to remove 2 capacitors.
The Second modification is only required to
solve a problem with
daisy-chaining on the GS Smartport, though the modified Duodisk will
still work
fine on older Apple II's. It requires removing a resistor.
DUODISK MODIFICATION #1- REMOVAL OF TWO CAPACITORS
This mod should be done on ALL Duodisks, no
matter whether they're used on
//e's, IIGS's, etc. The problem was that diskettes would sometimes
be damaged
when doing an Open-Apple-CTL-Reset or when using disks with certain
kinds of
copy protection. The mod was in an Apple dealer service bulletin
several years
ago for "analog board PN 676-[]101 or 676-[]102."
The Analog board is the one inside Drive 1
in the Duodisk. You may have
to unplug the cable near the back right of the board to see the board's
model
number. Anyway, if you have the -101 or -102 board, just snip
out Capacitors
C29 and C30 at board locations A1 and B1, respectively.
DUODISK MODIFICATION #2- REMOVAL OF A RESISTOR
This mod should be done for Duodisks used with
a GS; otherwise, it is
optional. The problem is that the Duodisk draws just a little too much
current
when connected to the GS Smartport. This can render other drives on
the chain
inoperable. Problems are MOST likely to occur when the Duodisk is daisy-chained
from a UniDisk 3.5 Drive. (ROM 3 GS users should check Q&A 007.)
Remove the top cover and turn the drive so
that the identifying
number will be at the bottom left of the analog board. The number
might read 676-[]101, 676-[]102 or 676-[]107.
If the I.D.# for the analog board is 676-[]101 or 676-[]102,
use
a pair of nippers and cut out resistor R8 (located at position A2).
If the I.D.# for the analog board is 676-[]107, use a pair
of
nippers and cut out resistor R39 (located at position C3).
From: Dave Althoff
There are two capacitors which must be clipped
from the board on the
DuoDisk regardless of what machine you intend to use them on.
Failure to do
this can lead to very nasty failures. For instance, some copy-protection
schemes can cause the drive to start writing unexpectedly-- say, during
a
re-boot-- thus trashing the disk without regard to the write-protect
switch.
From: Chet Gerhardt
I have done the capacitor removal mod with
all DuoDisks I have sold and my
own DuoDisks. It is amazing that after all of this time most still
have not had
the mod done.
007- Will a Duodisk function correctly on my ROM 3 GS?
I have three Duodisks. The one connected
to my flagship ROM 3 IIgs has
had the resistor and capacitors clipped out as recommended in a memo
from Mitch
Spector. It works perfectly!
From: Rubywand
A Duodisk may not be entirely functional connected
to the usual ROM 3 "Disk"
connector (i.e. the SmartPort). Users report that the system
may not start up unless
a write-protected disk is inserted in the Duodisk. Apple, in Tech Library
notes #5010
and #5434, mentions these reports and says that there is some code
in the ROM 3
ROM that does not handle the interface to a Duodisk properly. Apple's
workaround
is to connect the Duodisk to a drive interface card instead of to the
Smartport.
008- How do I fix a false Write Protect?
I recently ran into this problem with a Disk
II. It insisted the disk was
write protected. I checked the write protect switch, but it was okay.
I pulled
all the chips out of the analog board inside the drive, cleaned the
contacts
with a clean pencil eraser (one was _really_ dirty, almost looked burnt)
and
re-installed them. Voila! The problem went away.
009- My 800K, 3.5 Disk Drive is no longer working on my IIGS.
When a disk is inserted the drive tries
to read it and then
locks up the entire system forcing me to
do a 3 finger reboot.
Any suggestions on where to start troubleshooting?
If you have a SCSI interface card plugged into
your GS, you may have run
into a bug which seems to affect setting up of the diskette port. (See
the next
question and answer.)
Try cleaning the heads using a Head Cleaner
Diskette, such as a paper
diskette + cleaning solution kit from Radio Shack. (See Q&A
004.)
In a few rare cases, a drive may actually have
globs of dust inside which
end up interferring with its operation. You can shine a flashlight
into the slot to
check for a heavy dust buildup. The safest way to clean out dust is
to open
the case and the drive and remove the dust. However, you can try inserting
a
small cheap plastic artist's paintbrush (slightly dampened) into the
slot and,
with a flashlight, _lightly_ sweeping around to pick up dust. ("Lightly"
means
you do not push or snag on anything, especially the R/W heads.) Blow
into
the slot and do another sweep with your brush.
If cleaning does not seem to help, try wiggling
the drive cable while
attempting to CAT a known-good, unprotected diskette in the drive.
If wiggling
helps, you are likely to have a bad cable or a GS plug with a loose
connection
to the motherboard.
Try formatting a diskette. A drive which can
format and R/W diskettes it
has recently formatted but cannot read most other diskettes probably
has heads
which have become misaligned.
Set your boot Slot to Slot 5 and try power-up
booting a couple bootable
ProDOS diskettes known to be in good condition. If you can boot a variety
of
disketts, including commercial game, etc. diskettes, the odds are pretty
good
that your drive is okay.
A 3.5" drive that, after cleaning, cannot boot
known-good diskettes is
likely to have screwed-up heads. However, it's a good idea to try unplugging
and re-plugging the drive (with the computer OFF) and, then, try another
boot.
If you have a 5.25" drive attached, boot ProDOS
from the 5.25" drive and
try some CAT's of non-protected known good 3.5" diskettes in the 3.5"
drive. As
earlier, do the cable wiggling test while attempting the CAT's.
A very good test is to try out the drive on
a friend's IIgs or IIc+. If it
continues to bomb, it is likely to have R/W heads which have become
badly
misaligned, heads which are badly worn, or heads which have been partially
dislodged from the mountings. (The 3.5" drive's heads are held in place
by
springy metal sheets. Unlike the mounting for the 5.25" Disk ][ head,
these are
fairly delicate. If anyone has tried cleaning the heads by sticking
in an
alcohol swab and 'swishing around', there is a good chance the head
mountings
are messed up.)
Shops which replace heads are fairly rare.
I had this done a few years ago
and the drive still works fine. However the charge is around $80. It
is cheaper
and easier to get a good 2nd-hand drive at a swap-meet. You can, also,
look for
a bargain Mac drive and do a "transplant" as described by Steve Buggie
in the
Winter 1996 issue of II Alive.
Steve Buggie is a good source of information
on drive repairs. Check out
some of his recent posts to this newsgroup.
010- Sometimes the 3.5" drives on my GS do not
function correctly.
This started after adding a SCSI interface
card. Is there a fix?
This problem seems to crop up from time to
time, especially when a SCSI
interface is present and when no device is connected and recognized
on the SCSI
chain. (For example, you may have only a Zip Drive connected to your
SCSI
interface; but, it is not powered ON or no Zip disk is inserted.)
Evidently, something (e.g. a register or softswitch)
involved in the usual GS
power-up routine relating to on-line devices gets messed up. Arranging
to have
some active, on-line device on the SCSI chain (or removing the SCSI
card) seems
to help reduce frequency of the problem.
A nearly certain fix is inserting a 3.5" diskette
into Drive 1 before or just after
power-up. This usually forces recognition of 3.5" diskette drives and
enables
correct functioning.
011- Both of my Disk ]['s come on when booting! How can I fix this?
Basically, it sounds like Drive 2 does not
know when to stay OFF. There
are three fairly high-probability places where a glitch may cause this
to
happen:
1. The 74LS132 on the Disk ][ Controller card may have a blown
gate or some
pins may be making poor or no contact. Try unplugging and re-socketing
the IC.
This usually takes care of bad contact problems. (Or, you can replace
the
74LS132 IC with another 74LS132 or 74132. A 74LS00 or 7400 may work,
too.) Also
unplug and re-socket the 9334 and 556.
2. The ULN2003 IC on the Drive 2 main circuit board may have a
bad gate or may
have developed some poor pin-to-socket contacts. Remove the drive cover.
Unplug
and re-socket the ULN2003 IC. (Replacing a blown ULN2003 should not
be too
difficult. Both Mouser and Newark carry the IC.)
3. Drive 2's cable may have developed a short between pins 14
and 16. Mark the
position of the cable at the Controller card and at the Drive 2 circuit
board
and unplug the cable at each end. Use an Ohm meter to check for shorts
between
adjacent pins. If you find a short between 14 and any other pin you
can try
repairing the cable or cutting out line 14 and running a new lead;
or you can
get a replacement cable.
012- In connecting a second Disk II drive to my Disk II card I
misaligned the connectors. The result upon
turning it on was a
static-like clicking noise. Now I can't
load anything from
disk. Is the Disk II card dead? Are the
IIe and Drives all
right?
Try removing the drive which was connected
incorrectly. If your system
boots from the remaining drive (connected in the Drive One position),
this is a
fairly good indication that the Disk II card and IIe are okay and that
the
removed drive is messed up.
If it looks like a drive is bad, remove the
cover and inspect the drive's
main circuit board for blown components. If nothing obvious shows up,
a decent
fix try is to replace the 74LS125 IC on the drive's main circuit board.
(Also,
see Q&A 013.)
From: Ryan Underwood
I accidentally offset a row of pins on the
//e disk controller card when plugging
one of the drives in. Snap, crackle... you get the picture. I opened
up my freshly
fried Disk II, and in the center of the board there is a 74LS125 that
is blown.
Replaced it (it was socketed) with the same chip from another Disk
II, and voila!
it works again.
I would assume that misaligning the drive connector
on the controller is what
blew the 74LS125 in several Apple II drives before they got to me.
Note
that while the genuine Apple Disk II simply lights the LED and doesn't
move the
head at all when this IC was blown, a Mitac drive actually ate disks.
So any
number of dead Apple II drives with different symptoms could have a
blown
74LS125.
013- Last night a sound like a shotgun going off came from my 5.25"
Disk ][ drive. Now it doesn't work. How
can I fix it?
The noise was probably an electrolytic capacitor
exploding. Sometimes,
these develop internal shorts, heat up, and blow (kind of like a sealed
can of
beans on a campfire).
The fix is to remove the drive cover and replace
the blown capacitor.
(Look for a small can-like component with goo and/or shredded foil
coming from
it.) Circuit board markings should help identify the component. Here
are some
suggested replacement values:
C2 (on +12V line): 220uF-500uF at 20V-50V
C4 (on +5V line): 470uF-500uF at 10V-25V
C5 (on -12V line): 10uF-50uF at 20V-50V
If there is some difficulty identifying the
blown capacitor, replace it
with a 500uF unit rated at 20V-50V.
Before removing the bad capacitor, note which
lead is connected to the
outside 'can' part and mark the circuit board where this lead is connected.
This is the Negative side of the capacitor. When installing the new
capacitor
make sure its negative lead goes to the marked point on the circuit
board.
014- Recently I picked up two 3.5" drives at a swap meet-- a
Uni-disk and a Laser 128 drive. I've tried
cleaning the
heads; but, neither works with my IIc.
What's the problem?
The 3.5 UniDisk won't work on the earlier IIc
unless the IIc has had a ROM
upgrade. The Laser 3.5 is actually a Macintosh drive with the addition
of an
eject button. It isn't compatible with any Apple II unless it has a
special
controller card, which of course a IIc doesn't.
015- Can I replace a bombed Apple II 3.5" drive mechanism with
one from a Mac?
Yes. 3.5" drive mechanisms are cheaply and
abundantly available from the
Macintosh world. Although Apple II users have increased their interest
in 3.5"
drives, these drives have declined in their utility for Mac users who
have
shifted to hard drives, CD-ROM, and flopticals. Few Mac owners
have use for
the external 3.5" drive any more; if they have not yet discarded their
external
3.5" drive, it is now in storage.
MAC AND APPLE II 3.5" DRIVES: SIMILARITIES/DIFFERENCES
The basic Sony 3.5" mechanism is shared by
Mac and Apple II. It stores
800K of data on a two-sided disk. Unlike the IBM version with
its constant
rotational speed, Mac/Apple II drives maintain constant head velocity
by
varying the rotational speed as the head assembly approaches towards
or moves
away from the disk hub. Mac and Apple II drives differ in their
track
sectoring arrangements, so disks cannot be read directly without special
translational software. The opportunity for compatible disk sharing
was lost
during development, because rival teams working on Mac/Apple II drives
went
their separate ways (Steve Weyhrich, APPLE II HISTORY, Pt. 9, 1992).
The platinum 3.5" drive supplied with the IIgs
is directly compatible with
the Mac, although the Mac ignores its front panel manual eject button;
Mac disk
ejection is handled strictly by the desktop trash icon command.
An older
version of the external Mac 3.5" drive lacks the manual eject button
and, in
its casing, is plug-incompatible with Apple II. Thanks to advice
provided by
Ken Watanabe, I learned that the inner mechanism is identical among
all
versions of 800K Mac and Apple II drives, including the internal drive
mechanism in the Mac CPU. This is good news for Apple II users
who wish to
transplant the abundantly available Mac mechanism into their platinum
3.5"
drive casing.
WHAT ABOUT THE APPLE UNIDISK 3.5" DRIVE?
The classic white UniDisk drive was released
in 1985 as a 3.5" platform
for the IIe and IIc. This release date was 18 months prior to
the introduction
of the IIgs. Disks written by the UniDisk 3.5 and Platinum 3.5
drives are
fully interchangeable; the two models differed because the earlier
UniDisk 3.5
used an intelligent microprocessor-controlled analog board to slow
the data
transfer rate to match the IIe/IIc parameters. This slowdown
was not needed
for the popular platinum 3.5 drive used by the IIgs.
Can the Mac mechanism be transplanted to the
UniDisk 3.5 casing? Probably
yes, but this has not yet been verified. I am reluctant tohack
with the
working UniDisk 3.5's attached to my IIC's. I now seek a mechanically
jammed
UniDisk 3.5 drive to verify whether its life can be resurrected with
a Mac
transplant.
FINDING A USED MAC 3.5" DRIVE MECHANISM
The internall DSDD 800k drive mechanism can
be salvaged from any
mid-vintage Mac except for early models (Mac 128, Fat Mac 512) ----
those two
models used a quaint single-sided 400k drive. Suitable models
include the Mac
Plus, Mac SE, Mac II, or other Macs that have the standard DSDD 800K
mechanism
--- newer Macs have incompatible high density drives. Get a genuine
Mac Sony
drive mechanism, not a clone; the suitability of non-Sony clones is
uncertain.
Salvaged internal drives must be removed from
the Mac internal mounting
bracket --- take out the four side-mounted bolts, and slide the mechanism
forward. The early version of the external Mac mechanism is mounted
in a
plastic casing that resembles the Apple II platinum drive except that
the
manual eject button is absent.
Remove the mechanism from the casing, but save
its round external cable
and db-19 plug --- that cable/plug can be used later to adapt flat-ribbon
Apple
II drives for use with the IIgs or IIIc! The Mac externaldrive's
plastic
casing can be saved for use as a coin bank, or discarded.
You should anticipate that the older
Mac drive has had plenty of use;
most Mac users have fewer drives attached to their computer than is
common for
the Apple II.
The 3.5" drives are sturdier than hard drives,
but to protect the drive's
head assembly from damage during rough shipment, the seller should
be asked to
ship the unit with a disk inserted.
DISASSEMBLY OF THE APPLE 3.5" PLATINUM DRIVE
Use a well-light work area that gives you plenty
of elbow room, with
containers to hold bolts and other small parts All dimensions
(left/right/top/bottom/front/rear) refer to the unit's own dimensions,
NOT to
your own egocentric viewpoint as the observer. Standard precautions
against
static or other electrical damage must be followed: Discharge static
frequently
by touching grounded metal, wear a grounded wrist strap, hand all power
OFF
when attaching/removing drives, put insulating tape over the db-19
drive plug
when not in use.
Move slowly and patiently when removing or
inserting the mechanism from
its housing ---- metal parts must not be forced or bent. These
tools
areneeded: (a) medium and small Phillips-head screwdrivers, (b) a small
pliers,
and (c) a fine-tipped felt marker. This procedure was outlined
in an essay by
Lorne Walton (Apples BC, 1992), but many further details have been
added here
to facilitate disassembly and drive replacement.
The first step is to remove the worn/defective
mechanism from its Apple II
platinum casing. Flip the casing on its back and rest it on soft
cloth.
Re,ove the four shiny bolts from the bottom of the casing. With the
unit
inverted, slowly lift the bottom half-shell of the plastic casing upward
and
push the external cable's attached grommet towards the upper casing.
The
unit's bottom casing should come off cleany.
Use the felt marker to label the unit's own
main dimensions, writing on
the metal internal shroud: front-bottom, rear-bottom, left side, right
side.
Examine the metal innards as they lie upside down in the upper casing.
Note
that a red and black wire pair are tucked on the inner edge of each
side ---
These two wires go to the eject switch (right front) and to the red
in-use LED
lamp (left front).
At the unit's rear, observe that the wire pairs
terminate in RED and BLACK
plugs. Use the felt-tipped marker to write "R" and "B" on nearby
metal
surfaces to identifythe positions of these two plugs. These letters
will help
during reassembly when reinsterting the two plugs onto their proper
pins.
Next, use the small pliers to grasp each plug, slowly and carefully
pulling it
backwards to remove it from its mounting pins.
With the black and red plugs each removed,
slide the top plastic cover in
a rear-to-front direction, past the metal-enshrouded mechanism. The
wire-pairs
from the eject-button and also from the in-use LED lamp should remain
tucked
into their plastic side-braces.
You now hold the mechanism, enshrouded in its
grey metal shielding, with
the external db-19 cable protruding from the rear. Remove the two medium
Phillips mounting bolts (with flat washers) from each side. Remove
the single
medium Phillips bolt/washer that is centered on the upper-rear metal
shroud.
Then lift off the upper-rear should and look inside.
Note that the round external cable terminates
in a familiar IDE-20
flat-ribbon connector that plugs into the inner mechanism. Unplug
that inner
connector --- the small pliers can be used to rock and pull the connector
towards the rear. With the IDE-20ribbon connector unplugged,
the inner
mechanism can be slid forward and out.
As you hold the inner mechanism in your hand,
observe that a shiny thin
metal shroud covers its to and sides. Use the felt-tipped pen
to label this
shrou's dimension: TOP-FRONT and TOP-REAR. This thin shroud should
be removed
by rocking it and spreading its thin side-tabs. At this point,
you have the
bare mechanism in your hand, with heads visible from its top perspective,
and
with pancake motor visible underneath.
You are now ready to begin reassembly, but
pause to appreciate what is
before you. Hold the old mechanism and its Mac replacement side-by-side
---
they should appear identical. The date of manufacture is coded
on a sticker on
the pancake motor (e.g., 8809 = September 1989). Apply rubbing
alcohol with a
cotton swab to clean the surfaces of both read/write heads.
REASSEMBLY
Remount the innermost top-and-sides metal shroud,
taking care that its
"fingers" have clicked into place on the mechanism's sides. When properly
fited, both bolt-holes on each side will be visible through the shroud's
thin
metal. If the shroud does not fit, or if the bolt-holes are not seen,
check
with your dimensional labels to verify that the front and rear have
not been
reversed.
With the top/side inner shroud correctly in
place, then reverse the
disassembly steps: Slide the mechanism through the front of the metal
shroud.
Reattach the IDE-20 internal ribbon connector, align the two bolt holes
on each
side of the outer shroud with the mechanism and reinstall the four
medium
Phillips bolts and their washers. Then reattach the rear-upper
shroud with its
centered bolt and washer. Reassembly of the outer metal shroud is now
finished!
The final reassembly task is to refit the enshrouded
mechanism into the
plastic outer casing. Lay the inverted UPPER plastic half-shell
on the
bench,with its front facing away from you.
Observe the small red or black wires tucked
along the sides of the upper
plastic half-shell. With the metal enshrouded drive mechanism upside
down, it
should be slid into the plastic top-shell, from its rear to its
front. Check
that the red-black wires remain tucked along the inner edge between
the plastic
casing and the metal shroud. Insert the black and red plugs into
their
respective connectors. Note the "R" and "B" markings you wrote
on the metal
shroud; those markings will guide the plugs' insertion into their proper
connectors.
The oblong-shaped grommet attached to the round
external cable should be
fitted first to the bottom plastic half-shell casing, which is then
mated to
the top casing. Reattach the four small shiny Phillips bolts
through the
bottom plastic half-shell, and you're done!
016- I have one 5.25" drive connected to my GS, but the System 6.0.1
Finder display shows two 5.25" icons!?
How can I fix this?
You need to change the AppleDisk5.25 driver
file's auxilary filetype from
$010E to $0101. You can use File Manager (an NDA utility) to make the
change.
For a standard GS/OS device driver, the lower
six bits specify the number
of devices supported by the driver (see the file type note on GS/OS
drivers:
FTN.BB.XXXX), so the maximum number of devices that can be supported
by a
single driver is 63. You should NEVER increase this higher than
the original
value, because the driver probably doesn't have space in its device
tables to
support more drivers than it originally claimed to.
The AppleDisk5.25 driver supports a maximum
of 14 devices - two 5.25"
drives for each available slot. (In theory, it should be able
to support 16:
all seven real slots, plus the built-in disk port, but Apple never
completed
the implementation of dynamic slot switching for drivers, probably
for
compatibility reasons.)
Don't change any of the higher order bits.
The high order byte specifies
the type of driver ($01 = GS/OS device driver), and the top two bits
of the low
order byte specify the type of GS/OS driver (00 = standard).
NOTE: All of the above applies ONLY to GS/OS standard device drivers,
not to
GS/OS supervisory drivers, printer drivers, or anything else. See the
filetype
note for further information.
There is one bit in the auxiliary type which
is the same for all types of
drivers: bit 15 set ($8000) indicates the driver is inactive (this
is what
Finder toggles when you click on the "Inactive" check box).
017- How does one distinguish between a 13 and 16-sector Disk ][
controller card?
For a while at least, new 16-sector Disk II
cards shipped with a little
white circular sticker depicting a red Apple with the number "16" in
the
middle.
But the sticker is hardly a reliable test.
A better test is to look look
at the part numbers of the P5 PROM (the lower left chip on the card)
and the P6
PROM (left column, second from the top).
13-sector. . 16-sector
P5 341-0009-xx.
.341-0027-xx
P6 341-0010-xx.
.341-0028-xx
The 16-sector PROMs may also be labelled "P5A" and "P6A".
A program can test the card type by looking at its slot ROM space.
The
signature bytes are as follows:
$Cn01: 20
$Cn03: 00
$Cn05: 03
$Cn07: 3C
$CnFF: FF if
13-sector; 00 if 16-sector
For example,
1 REM Scan the slots for Disk II
interfaces
2 REM By Neil Parker
10 FOR S = 1 TO 7
20 A = 49152 + 256 * S
30 IF PEEK (A + 1) <
> 32 OR PEEK (A + 3) < > 0 OR
PEEK (A + 5) <
> 3 OR PEEK (A + 7) < > 60 THEN 100
40 PRINT "Disk II (";
50 T = PEEK (A + 255)
60 IF T = 0 THEN PRINT "16-sector";:
GOTO 90
70 IF T = 255 THEN PRINT "13-sector";:
GOTO 90
80 PRINT "other";
90 PRINT ") in slot "S
100 NEXT
018- Can a Disk ][ Drive be used on a IIc or GS smartport?
Yes. Call Jameco Electronics. Get the S20-pin
header- to -DB19-pin
connector module. It is intended for adapting II/II+ drives for IIc.
(Part#
10022; Product name: AAM APPLE IIC ADAPTER; price: $3.95)
019- I would like to add a Read/Write indicator to my Disk ][
drive. How can I do this with a bi-color
LED?
The circuit described below works well. It
shows Red for Drive Enabled +
Write and Green for Drive Enabled + not Write. That is, a Read is assumed
if
the drive is ON and no Write is occurring. The advantage of this approach
is
that you always have a lighted LED 'drive ON' indicator and, so, there
is no
need to drill a new hole in your drive panel. The new LED can use the
hole
occupied by the old "in Use" indicator LED.
Parts
IC- 74121 or 74LS121 1-Shot multi-vibrator
Qgreen- 2N2222A gen purpose NPN transistor
Qred- 2N2222A gen purpose NPN transistor
Rcath- 120 Ohm 5% 1/4 watt resistor
Rgreen- 3.3k 5% 1/8 watt resistor
Rred- 3.3k 5% 1/8 watt resistor
Rp- 20k 5% 1/8 watt resistor
Cp- 10uF/10v 10% "dipped tantalum" capacitor
LED- 2.2V 20ma 3-lead (common cathode) Green/Red
bi-color LED
Building the Circuit
IC- locate pin-1 and mark it on bottom side with white-out.
'Dead-bug' mount the IC using epoxy in the open area near
top-middle of board with pin-1 end pointing to the right.
connect Rcath to solder pad at - (minus) end of C2
connect #20 wire from IC pin-7 to solder pat at - end of C2
connect Rp from IC pin-11 to IC pin-14
connect Cp + to IC pin-10 and Cp - to IC pin-11
connect #20 wire from IC pin-14 to solder pat at + end of C4
connect a wire from IC pin-3 to end of R16 closest to 74LS125
connect Rgreen to IC pin-1 (74121 "/Q" output)
connect Rred to IC pin-6 (74121 "Q" output)
solder transistor Qred Collector to Q1 power transistor Collector
(solder pad area at left front of circuit board just to left
of
the power transistor). Position toward left edge of pad.
solder transistor Qgreen Collector to Q1 power transistor Collector
solder pad to the right of Qred.
LED- connect a 3-wire 11" cable to the LED (black to center, red
to
to lead with right-angle bend, green to lead with slant
bend).
Old "in Use" LED- pop off the retainer ring and push through the
LED. Leave the LED mount in the hole. Cut off the LED, spread
cable ends and tab over with cellophane tape. (Put old LED
and
ring into parts box.
Spread apart retainer 'leaves' of LED mount (at back side of panel)
to permit easier insertion of new 3-lead LED.
Run LED + cable over back of board and along bottom toward the
hole in the front panel. Push through hole. (If hole is
too small,
use a Dremel tool and steel 'bulb bit' to slightly enlarge
front
part of hole.)
connect LED cable black to free end of Rcath
connect LED cable green to Emitter of Qgreen (right transistor)
connect LED cable red to Emitter of Qred.
position old LED cable beneath new LED cable.
connect a wire from the free end or Rgreen (on IC pin-1) to the
Base lead of transistor Qgreen.
connect a wire from the free end or Rred (on IC pin-6) to the
Base lead of transistor Qred.
Add epoxy to the back of the LED and holder to secure the LED.
How it Works
When /Enable goes low to select the Drive,
the power transistor (Q1)
switches ON and supplies +12V at its Collector. If there is no Write,
74121
output /Q is high, Qgreen conducts, and the LED shows Green. That is:
the Green
LED will light during boots and for any READs.
If the Drive is selected (/Enabled is low)
and there is a Write operation
and Write Protect is not ON, then, the /Write Request signal at 74LS125
pin 8
will go low. This triggers the 74121 One-Shot (at pin 3) producing
an aprox.
160ms pulse at 74121 output Q. For the duration of the pulse, /Q is
low and Q
is high. Qred conducts, and the LED shows RED to indicate WRITE.
020- What's the scoop on the 3.5" High Density drive?
In order to do High Density on the Apple II,
you will need both the High
Density 3.5" drive and the Apple 3.5" HD controller. If you don't have
both,
you will only be able to do regular density. Of course, you will also
need High
Density diskettes.
Once you have collected the above items, you
are in for a pleasant
surprise. ProDos 8 programs not only recognize it, but most programs
format and
recognize HD disks just fine. You can even boot off of a HD disk, allowing
plenty of room for System Desk Accessories and such.
There are a few drawbacks: You cannot boot
copy-protected software or some
FTA demos. You can't daisy-chain a 5.25" on an HD card. Also, it takes
up a
Slot, even on the GS.
021- What is a "UniDisk"?
The UniDisk 5.25 was Apple's replacement for
the venerable Disk ][. It
featured an updated design, tan color plastic case, a DB-19 cable,
and
daisy-chain port on the back to which other drives could be connected.
The case
color was later changed to platinum and the drive was rechristened
to the
"Apple 5.25 Drive".
The UniDisk 3.5 was Apple's first 3.5" drive
for the Apple II line. Like
the UniDisk 5.25, it had the DB-19 cable and daisy chain port on back.
UniDisk
3.5 was dropped in favor of the Apple Disk 3.5, a different design,
at the time
of the launch of the IIgs.
----------------------------------
From: Mitchell Spector
One important difference you forgot to mention:
The UniDisk 3.5 was an
"intelligent" drive, whereas the Apple 3.5 was a "dumb" drive. There
was a
specialized circuit board inside the UniDisk 3.5 drive which had its
own
processor, memory, IWM controller and firmware. This was needed for
the //c, in
order for the drive to process data before sending it on to the machine
(which
was too slow to do the job by itself). You can easily spot a UniDisk
3.5 as it
matched the snow-white color of the //c and had its access LED and
eject button
_above_ the disk insert slot (the Apple 3.5 has them in-line).
022- What is a "RAM disk"; and, how do I create one on my IIgs?
A RAM disk is a block of memory which your computer uses like a disk.
To create a RAM disk on your IIgs ...
o- Boot a ProDOS-8 or DOS 3.3 diskette; or, start your computer with
no
boot and press CONTROL-Reset to get to the Applesoft prompt.
o- Press OpenApple-Control-ESC (all three keys at once) to get to the
Desk Accessories menu and select "Control Panel".
o- In the Control Panel menu, select "RAM Disk".
o- Set "Minimum RAM Disk Size" and "Maximum RAM Disk Size" to the
the same value = size of the RAM disk you want. If you have enough
RAM
left over to start your operating system and run your favorite application,
a
good RAM disk size is 800k.
o- Press Return to set the value. Exit the Control Panel. Exit the Desk
Accessories menu. Turn OFF the computer.
When you next power up your computer, your
RAM disk will be ready
to use.
023- Which 3.5" drive/interface combinations work on a IIe?
For the UniDisk 3.5 (model number A2M2053),
you need either Apple's
"SuperDrive" card or the "Liron" card. The UniDisk 3.5 is quite rare.
It is a clean
white color instead of greyish "platinum". It also has the eject button
just above
the line of the disk insertion slot, with a separate manual ejection
hole.
The "Liron" card's official name is "Apple
3.5 Floppy Disk Drive Interface
Card". It has the word "Liron" on the back (which is the nickname of
the IWM
disk controller chip, if I remember right).
For the Apple 3.5 Drive (model A9M0106 as used
on the IIgs), you need
either Apple's "SuperDrive" card or the third party "Universal Disk
Controller"
card. The drive is platinum in color and has the eject button in line
with the disk
insertion slot and the ejection hole is in the middle of the button.
The "SuperDrive" card's official name is "Apple
II 3.5 Disk Controller Card".
The card has an LED on top, and has its own processor, RAM and ROM.
For the Apple SuperDrive, you need the "SuperDrive"
card. Model ID is
inconsistent. Check for something like "Family number G7287".
The SuperDrive looks exactly the same as the
Apple 3.5 Drive. It supports
1.44 MB high density and 720 KB double density disks as well as the
400 KB
and 800 KB formats. You can use a SuperDrive with the Universal Disk
Controller card, but you won't be able to use its extra capabilities,
and it will
behave like an Apple 3.5 Drive.
From: O Aaland and Michael Pender
024- How can I boot from my /RAM5 RAM disk? All the files are there
but it just beeps at me and says 'check
startup device'!?
When GS/OS boots, the RAM disk is formatted;
but, the boot blocks for
ProDOS are not written. That is why you can not boot from it if you
just copy
files or install a system on it.
For the RAM disk to be bootable, you need to
do a whole-disk copy of a
same-size bootable diskette to the RAM disk. Or, you can initialize*
the RAM
disk before you copy files to it or do an install.
*Note: To initialize the RAM disk, click on the RAM disk icon to select
it. Then,
click on "Disk" on the menu bar and select "Initialize". Follow the
prompts to init
the disk.
Finally, in the IIgs Control Panel,
go to Slots and set Startup Slot to "RAM
Disk".
025- My 5.25" drive ruins every disk I insert. How can I fix it?
Probably, the drive's Write signal is ON when
it shouldn't be. This happens with
some 5.25" drives when a 74LS125 IC on the drive's circuit board is
blown. (I
accidentally offset a row of pins on the //e disk controller card when
plugging in a
drive and blew the IC.)
I removed the drive cover and replaced the
74LS125-- it was socketed-- voila!
it worked again. (For possible disk-trashing fix for DuoDisk drives,
see Q&A 006.)
026- I have a 3.5" UniDisk drive on my GS that has performed
flawlessly for years. Recently, when I try to save a file to
a diskette, I get a 'Disk Full' message; but it isn't full.
This happens with other diskettes, too. What's going on?
There is a known problem when attempting to
save an Appleworks file to a
3.5" UniDisk drive when the disk in the drive is write-protected. It
ruins the
disk for future use, and you can't save to it any more. If you try
to save to
that disk again later, the situation you describe will happen.
From: Mark R. Percival
Perhaps the cable has come loose at the back
of your IIgs or there is some
buildup of corrosion on the pins. I had a similar problem with an Apple
5.25"
drive once that ended up beng that. Try unplugging your drive and making
sure
the contacts are clean and then plug it back in.
