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1985-07-19
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ALIGN
Version 1.6 for the IBM PC
5/23/84
(c) Copyright John L. Dickinson 1983, 1984
COPYING PROVISIONS
This program and documentation may be freely copied and shared
provided it is not modified in any manner and this notice is not
bypassed or removed. Please keep the ALIGN.DOC documentation file
on the same diskette with ALIGN.EXE.
If you find the ALIGN program useful, a contribution will be
appreciated. ($20 suggested.) Comments or suggestions concerning
ALIGN are welcome at any time.
John L. Dickinson
2470 N. Tierra Verde Pl.
Tucson, Arizona 85749
PROGRAM OVERVIEW
The ALIGN program allows you to move a diskette drive head to
absolute track locations and operate the drive while checks and
adjustments are made. 40 track single or double-sided drives are
supported.
ALIGN is one of several tools needed to adjust and service
diskette drives. The ALIGN program does not attempt to teach you
how to do an alignment, but it isn't difficult if you have what
you need. In addition to this program, you should have:
The drive manufacturer's alignment and service procedures.
An oscilloscope (dual trace with triggered sweep).
A DYSAN double-sided analog alignment diskette for 40 track
drives, 224/2A #800180.
Extension or external diskette drive signal and power cables are
very helpful.
See the notes at the end of this document for possible sources for
these items.
An analog alignment diskette contains NO data, just special
waveforms and can't be copied. (It's really copy protected!) You
can try the program using any diskette. The ALIGN program does
not write on diskettes.
(It should also be possible to use this program to adjust 80 track
drives provided you have the proper alignment diskette. However,
some of the program commands may not be useful since they have
track addresses hard coded for the 40 track alignment diskette.)
ALIGN Version 1.6 Page 2
SYSTEM AND DISKETTE DRIVE REQUIREMENTS
ALIGN runs under IBM PC-DOS on a PC or PC/XT with at least 64K and
an 80 column display, either monochrome or color.
Since ALIGN uses standard BIOS interfaces for all I/O, it should
also work on most IBM compatibles. It does not work properly on
the PCjr.
The diskette drives to be adjusted are connected to the PC in the
usual manner. The ALIGN program works with standard IBM (Tandon)
diskette drives and should work with others that use the same
electrical interface.
USING THE ALIGN PROGRAM
Enter ALIGN after the DOS prompt and press any key to get past the
initial screen to the main command menu. Chances are, you'll be
able to use the program without reading any more of this
documentation.
Commands are entered one at a time on the command line. All
commands may be abbreviated and the first letter is sufficient for
all but one command. (INFO requires the 3 letters, INF.)
Some commands require one operand as listed on the menu. Numeric
operands, such as track number or seconds, are decimal. The first
track is track 0, not track 1.
If the diskette drive under test is running, pressing any key will
cause it to stop in about 2 seconds. This key may be the first
letter of the next command or any key such as the RETURN key. The
drive will stop by itself after 60 seconds.
If the drive is stopped and and you want to continue the previous
motion command, simply press the RETURN key. This enters a
null command which is interpreted just like a GO command.
Commonly used commands may also be entered using the program
function keys as shown on the command menu.
ALIGN Version 1.6 Page 3
ALIGN PROGRAM COMMANDS
DRIVE A..D
The DRIVE command specifies the letter of the drive under test:
A, B, C or D. The default is drive B. The DRIVE command does
not cause the drive to start. Examples:
DRIVE A (Set drive A)
D C (Set drive C)
HEAD 0..1
The HEAD command selects the lower or upper head (diskette
side). HEAD 0 is the lower head and the only head on a single-
sided drive. HEAD 1 specifies the upper head on a double-sided
drive. The HEAD command does not cause the drive to start.
Examples:
HEAD 0 (Set head 0, the lower head)
HEAD 1 (Set head 1, the upper head)
H 1 (Set head 1, the upper head)
TRACK 0..39
The TRACK command moves the head to a specified track and starts
drive motion. The drive will continue to run until a key is
pressed or for 60 seconds. (The 60 second run time may be
changed using the SECONDS command.) The track number that may be
specified is usually in the range 0 through 39, although the
upper track limit may be extended using the MAX command.
Examples:
TRACK 0 (Move to track 0 and run drive)
T 34 (Move to track 34 and run drive)
T 16 (Move to track 16 and run drive)
IN
OUT
The IN command moves the head to track 32 and then immediately
moves it "in" towards track 0 stopping on track 16. IN is
equivalent to the TRACK 32 command followed by TRACK 16.
The OUT command is similar, but moves the head first to track 0
and then "out", away from track 0 stopping on track 16. OUT is
equivalent to a TRACK 0 command followed by TRACK 16.
Both commands end up on track 16 with the drive running. Track
16 is the radial head alignment track on the Dysan 40 track
alignment diskette.
ALIGN Version 1.6 Page 4
After making a head adjustment it's a good idea to re-seek to
track 16 and check the cat's eye pattern again. Both the IN and
OUT commands cause a re-seek to track 16. The two commands
also allow checking the accuracy of seeks (and the resulting
head alignment) in both directions. If there is a difference in
the cat's eye patterns in the two directions, you may want to
re-adjust the alignment to split the difference. A difference
indicates play in the mechanism or an imprecise head stepper
motor.
GO
If the drive is stopped, the GO command simply starts the drive
at whatever track it happens to be on. A null entry does the
same thing, so you can just press the RETURN key with nothing on
the command line to start the drive.
SECONDS 3..180
Normally, each time you start the drive using ALIGN, the drive
runs for 60 seconds if not stopped by pressing any key.
This is usually enough time to make a check or adjustment and
prevents the drive from running "forever". The SECONDS command
allows you to change this 60 second limit anywhere from 3 to 180
seconds. The SECONDS command does not cause the drive to start.
Examples:
SECONDS 120 (2 minutes)
S 10
S 30
CYCLE
The CYCLE command starts the drive and cycles the head through
tracks 0 through 3 in the following order 3,2,1,0,3,2,1,0,3,2...
and so on for the purpose of checking the track 0 switch. The
drive changes tracks every few seconds so you have time to see
if the track 0 switch has switched. In between each track
(0,1,2 or 3) the CYCLE command moves the head to track 16 so
there is a seek similar to that when a drive is first used after
power-on.
Believe it or not, on Tandon TM-100 series drives, the track 0
switch should switch between tracks 1 and 2. (It's NOT supposed
to switch at track 0!) This is a position in the middle of the
first four tracks. The actual track 0 signal on the drive
interface is a combination of the track "0" switch and other
indications in the drive electronics.
Switch here
|
V
0 1 2 3
ALIGN Version 1.6 Page 5
While the CYCLE command is active, the PC's speaker sounds rapid
beeps equal to the current track number, 1 to 3, each time it
changes tracks. Track 0 is a single longer beep. These beeps
allow you to know what track the drive is on without trying to
watch a meter or test light and the PC's display at the same
time. A higher pitch sounds in addition to the track beeps when
the switch should switch. After a little practice, the sound
eliminates the need to watch the screen. As you watch your
meter or light, don't be confused by the very brief switch
changes when the head moves out to track 16 and then back in.
While it's always nice to set things "right on," the track 0
switch adjustment isn't critical and the drive operates fine
even when it switches a whole track off from the ideal point
between tracks 1 and 2.
MAX 39..90
The MAX command sets the maximum track allowed with the TRACK
command.
Normally, the TRACK command accepts track numbers from 0 through
39. The MAX command allows you to change the TRACK command's
high track limit all the way up to 90. The MAX command does not
cause the drive to start.
There really isn't much occasion to use the MAX command. It's
most obvious use is to allow the ALIGN program to be used with
80 track drives. In this case you would specify MAX 79. (Note
that the IN and OUT commands assume a 40 track alignment disk
and won't be useful with an 80 track alignment disk. You can
still use the TRACK command to do the equivalent manually.)
Or, maybe you're looking for the track 39 signal on the DYSAN
alignment disk. If it doesn't appear on what the system thinks
is track 39, maybe it will show up at what the system thinks is
track 40, or 41 or....
Actually, there is a limit to how far the head will go past
track 39. You may want to use the MAX command to allow you to
investigate just how much further the head will go. (A copy
protection scheme might use one track past the "end" of the
disk.)
However, before you go charging off into the stratosphere of
track addressing, realize that when the head hits the upper
limit, it does so with the full force of the stepper motor.
This alone could knock a drive out of alignment or possibly
cause permanent damage. Use the MAX command at your own risk.
ALIGN Version 1.6 Page 6
RESET
The RESET command causes a reset of the diskette system (via
BIOS INT 13 with AH=0). RESET does not cause the drive to
start.
The next time any drive is accessed, it will then be
"recalibrated." This means that the diskette controller makes no
assumptions about which track the head is on, moves the head
until track 0 is located as indicated by the drive, and then
proceeds with the requested operation. Once this recalibration
process is complete, the diskette controller keeps it's own head
position register and simply pulses the head forward or back,
one step at a time to get to a desired track. If one pulse
is missed or the head is moved manually with power-on, then the
controller's track register won't agree with the physical
position of the head.
"Recalibration" is not an adjustment, but rather a normal
operation done by the diskette controller so it can get in sync
with the physical head position. Every drive is "calibrated" by
the controller the first time you use it after power-on or boot.
The RESET command allows you to recalibrate during the drive
adjustment procedure. For instance, assume the the drive is on
track 16 (or what you think is track 16). If you issue a RESET
command and then simply start the drive motion (null entry), you
will hear the drive move to track 0 and then back out to track
16 as the drive is recalibrated.
The RESET command is useful when servicing drives and you think
the drive is not seeking to the correct track. This could
happen while adjusting the track 0 switch. Also, the drive
won't seek to the correct track anytime the head has been moved
against the stepper's electrical hold. This could occur when
the head assembly hits it's travel limit at either end. This
isn't normal operation, but when the adjustments are wrong it
can (and does) happen.
If you don't find an alignment disk signal where you think it
should be, try the RESET command. It is also a good idea to use
the RESET command just before the final checks on radial head
alignment to be sure you're not exactly 1 or 2 tracks off.
ALIGN does an automatic RESET between every CYCLE command seek
to make track 0 switch adjustment easier.
Without the RESET command, it would otherwise be necessary to
re-boot or turn the machine off-and-on to force a recalibrate
operation.
ALIGN Version 1.6 Page 7
INFO
The INFO command causes another screen to be displayed with a
brief description of each track on the Dysan 40 track alignment
disk. It's simply for reference. Pressing any key returns you
to the ALIGN command menu screen.
QUIT
The QUIT command terminates the ALIGN program and returns to
DOS.
DRIVE SPEED TESTING
ALIGN does not have the capability to check a drive's spindle
speed. The IBM "Advanced Diagnostics" diskette that comes with
the IBM Hardware and Maintenance and Service book provides a good
software check of drive speed. Lacking that, use the ALIGN
program to run the drive while you observe the strobe disk on the
bottom of the drive.
INSTANTANEOUS SPEED VARIATION TESTING
To test Instantaneous Speed Variation, the Tandon manual says to
first "write a 2F (all ones) pattern on any track." The ALIGN
program won't write this or anything else on your diskettes. A
totally satisfactory substitute is to simply use the DOS FORMAT
command to format a work diskette in the drive under test. This
puts a pattern on every track. Admittedly, it's not "all ones"
but you'll hardly know the difference as you observe the pulse
jitter on the oscilloscope. Also, while Tandon says to use "any"
track, the jitter is much worse on the inside (high) tracks. Use
a middle track, such as 16, to check the specification. Get to
know what normal jitter looks like on tracks 0 and 39 too.
ALIGN Version 1.6 Page 8
TANDON TM-100 SERIES REPAIR TIPS
LOOSE SCREWS AND NUTS - HEAD MISALIGNMENT
In my experience, the most frequent cause of head misalignment and
drive failure on Tandon TM-100 series drives is a loose Allen head
screw on the stepper motor shaft. This allows the motor shaft to
slip where it connects to the split band positioner pulley.
Tighten this Allen head screw before doing an alignment. It's not
unusual to tighten it one-half turn holding the short end of an
Allen wrench with just your fingers. Don't over-do it, however,
as you could strip the threads.
The stepper motor shaft is smooth and has no flats or keys. As
long as you are doing an alignment and the Allen screw is tight,
the exact pulley position on the shaft usually doesn't matter.
But sometimes it can be out of the head alignment cam screw
adjuster range. If this happens, loosen the Allen screw, rotate
the pulley a bit, tighten it, and try again.
While you're at it, check the two nuts that hold the track stepper
motor to the casting. Also, remove the clear plastic cover on the
bottom of the head assembly and carefully tighten the little
Phillips screw that holds the split band on the pulley.
If you're not going to do an alignment, don't tighten these screws
since just tightening them might change the alignment some.
TRACK 00 SWITCH PROBLEMS - BOOT FAILURE
The track 0 microswitch frequently becomes intermittent or fails.
You can easily check this by powering-off the system and removing
plug 11 on the back of the drive. Push a few pieces of bare wire
into the connector and check the switch contacts with an analog
ohm meter. The switch is single pole, double throw (SPDT).
| | |
| | | <- wires to switch
------------
| | COM - common center contact
| Plug | NC - normally closed
| | NO - normally open
| |
Pin # -> |4 3 2 1|
------------
COM NC NO <- Switch contacts
Operate the switch manually. It is a little hard to get to and
you may want to remove the logic board first. Check to see that
contact closure is positive, occurs when the switch clicks,
and without any wavering around.
If the switch is not operating properly, the problem is usually
just a very small amount of corrosion or oxidation on the switch
contacts. Rather than replacing the switch, the easy and
ALIGN Version 1.6 Page 9
effective repair is to pass some reasonable current through the
switch and operate the switch a few times. Be sure that plug 11
is disconnected from the logic board and that you make connections
to just the plug. Use an external CURRENT LIMITED low voltage
supply to burn off the little bit of oxidation. I don't know how
much current to recommend. I use just enough to cause a little
spark when the power supply leads are touched, probably 0.5 or
1.0 amp. Be sure to use a current limited supply or put an
appropriate current limiting resistor in series. If you don't
know how to do this, then find someone who does rather than risk
any harm or damage.
POSSIBLE SOURCES FOR SUPPLIES
For the type of drives usually used in the PC, the alignment and
service procedures are in the Tandon "OEM Operating and Service
Manual TM-100-1 and -2 Disk Drives, 48 Tracks per Inch."
Priority One Electronics sells this as part number 07TND179022001,
for $36.00.
Priority One Electronics
9161 Deering Ave.
Chatsworth, CA 91311
Telephone (800) 423-5922
(818) 709-5111
It is also Tandon part number 179022-001, listed at $25.00 on a
December 1982 Tandon price list. I don't know if they will sell
it directly to end users.
Tandon Corporation
20320 Prairie Street
Chatsworth, CA 91311
Telephone (213) 993-6644
Analog Alignment Diskettes (AAD's) are available directly from
Dysan Corporation.
5.25" Double-sided, 48 TPI, 224/2A #800180 $50.00
5.25" Single-sided, 48 TPI, (numbers not known), $25.00
(96 TPI alignment diskettes are also available.)
Dysan Corporation
5201 Patrick Henry Drive
Santa Clara, CA 95050
Telephone (800) 551-9000, Dept 50
(408) 988-3472
Extension or external diskette drive signal and power cables may
be difficult to locate or you may have to make your own. Priority
One carries everything you need for the signal cable but not the
power cable. (If you know of a source for the male and female
power connectors in small quantities, please let me know.)