Copal F-5006 User manual

MAINTENANCE MANUAL
5.25" Mini Floppy Disk Drives
F-5006·
F-5008
.COPAL COMPANY, LIMITED
Memory Products Div.
2-16-20, Shimura, ltabashi-ku, Tokyo, JAPAN

MAINTENANCE MANUAL
5.25" Mini Floppy Disk Drives
July, 1985
F-5006
F-5008
Rev. 1
This Maintenance Manual is subject to change without prior notice.

CONTENTS
SECTION 3 Expl'7-nation of Operation ············ ··· ··············· ······ ····················· 300
3-1 Outline of Construction and Functions ··· ············ ··· ·················· ......... 301
3-1-1 Overal 1 block diagram ···. ·· ··· ··· ··· ··· ······ · ··. ·· ·.. ········· ··· ·········...... ... 301
3-1-2 Outline of structural parts ··· ··· ······ ··· ··· ············ ··· ··· ······ ······ ···... 302
3-2 Circuit Operation ······ ··· ··· ··· ··· ··· ······ ··· ······ ········· ··· ··· ··· ······ ··· ··· ··· ··· ... 305
3-2-1 Read/Write circuit ··· ··· ··· ············ ······ ······...·················· ··· ··· ··· ··· 305
3-2-2
3-2-3
Control circuit
Servo circuit
310
313
3-3 Test Point Functions and Type of Connector . ······ ······ ··· ······ ··· ··· ········· 314
3-3-1 Test point functions ··· ··· ··· ··· ········· ··· ......... ········· ···...········· ...... 315
SECTION 4 Explanation of Maintenance ............ ······ ····················· ... ············ 400
4-1
Maintenance Outline
4-1-1 Periodic maintenance
4-1-2 Inspection and adjustment
401
401
402
4-1-3 Replacement of maintenance parts ··· ······ ············ ··· ...... ············ ··· 403
4-1-4 Tools required for maintenance ······ ··· ··· •·· ········· ··· ··· ··· ··· ··· ···... ··· 406
4-2 Maintenance Cautions
407
4-2-1 Screw torque and screw lock ··· ···...··· ... ··· .................. ··· ··· ......... ··· 407
4-2-2 Handling the connectors ··· ......................................................... 408
4-2-3 Head cable treatment ..................... ············ ............... ······ ······ ··· 410
4-2-4 Others ··· ··· ··· ···...··· ·•· ······... ··· ··· ... ··· ··· ...... ··· .................. ··· · ..... ··· 412
4-3 Periodic Maintenance
414
4-3-1 Cleaning the magnetic heads with a cleaning disk ······ ............... 414
4-4 Inspection and Adjustment Methods ··· ··· ··· ··· ··· ··· ··· ··· ··· .................. ······ 415
4-4-1 Collet assembly centering adjustment ··· ··· ··· ··· ···... ······ ···... ··· ··· ··· 415
4-4-2 Front lever position adjustment ··· ··· ··············· ...··· ···•·· ··· ···...······ 417

4-4-3 Bail inspection and adjustment ....................•..•........................
4-4-4 Fi le protect sensor inspect ion ...•.. ·..·················· ·. · ................. .
4-4-5 Disk rotation speed inspection and adjustment ··· ··· ······ .............. .
4-4-6 Head touch inspection and adjustment ········· ··· ··· ··· ··· ··· ··· ........... .
4-4-7 Asymmetry inspection ··· ······ ··· ········· ··· ······ ··· ··· ··· ··· ··· ······ ........... .
4-4-8 Read level inspection ··· ............... ··· ··· .................. ··· ................. .
4-4-9 Resolution inspection ··· ··· ··· ··· ··············· ········· ······ ··• ······ ··· ........ .
4-4-10 Track alignment inspection and adjustment ...··· ······ ··· ................. .
4-4-11 Track 00 sensor inspection and adjustment ··· ······ ··· ··· ... ······ · ....... .
4-4-12 Track 00 stopper inspection and adjustment ··· ··· ··· ·················· ...
4-4-13 Index burst timing inspection and adjustment · ··. ·· · ................... .
4-5 How to Rep lace Parts ··················· ...··. ··· ... ·· .. · ..... · .......................... .
4-5-1 Head carriage assembly replacement ······ ········· ······ ···... ··· ........... .
4-5-2 Stepping motor and steel belt replacement ...... ······ .................... .
4-5-3 Disk Drive motor {spindle motor} replacement
4-5-4 Collet assembly replacement ············ ......................................... .
4-5-5 Track 00 block assembly replacement ··· ··· ......... ··· ··· ............ ··· ..... .
419
421
423
424
426
428
430
432
438
440
441
443
443
449
451
453
454
4-5-6 Main PWB assembly replacement ··· ······ ··· ········· ··· ··· ··· ··· ········· ··· ·... .. 455
4-5-7 Sensor block assembly replacement ··· ...... ······ ···. ·· ··· ...... ··· ............ 456
4-5-8 Front bezel replacement ······ ··· ········· ··· ··· .•.··•·•· ··· ··· ...··· ··· ...... ······ 457
4-5-9 Front lever assembly replacement ··· ... ··· ...······ ··· ... ······... ··· ··· ··· •·· 458
4-5-10 Cramp cam assembly replacement ··· ...··· ······ ··· ······ ··· ··· ...... ··· ··· ··· ··· 459
SECTION S Drawings and Parts Lists •·· ········· ······ ······ ··· ··· ··· ··· ••· ··· ·•· ·•· ··· ······ 500
5-1 Construct ion · ·· ···· ·· ··· ···· ·· · ·· · ·· ···· ·· · ·· · ·· ·········· ·· · ·· · ·· · ·· ··· ············· ·· ···· ·· .5()1
5-2 Structural Parts Exploded Drawing, Parts List ••· ··· ·•···· ······ •·· ···... ······ .5()7
5-2-1 Floppy Disk Ori ve chassis · ··. ········••·.··· •· · •·. •· • ··. ··· ... ··· ... ·· ...... ·..... .5()7
5-2-2 Screws and washers
................................. ... ..................... ......... 510
5-3 PWB Assembly Parts & Drawing No. List ...... ··· •·• ··· ··• ··· ··· ··· ...... ··· ··· ...... 511
5-3-1 Main PWB assembly ..................................................................... 511
5-4 Circuit Diagram ··· ...··· ...······ ...······ ······ ...... ············ ··· ··· •·· ······ ··· ··· ...... 516

SECTION 3
Explanation of Operation
-300-

3-1 Outline of Construction and Functions
3-1-1 Overall block diagram
REAO OATA
SIDE ONE SELECT
WRltE DAIA
DRIVE SELECT
0-3
WRITE GATE
HOTOR ON
STEP
DIRECTION
SELECT
IN USE
TRACK 00
INDEX
RF.ADY
WRITE PROTECT
+12V, •SV, OV
Read
Write
circuit
~
bl
..J
~
Control
circuit
Indicator
Hagnetic head
Irack 00 sensor
Stepping motor
File protect sensor
File protect sensor LED
Disk
Index sensor
Index sensor LFD
Spindle 110tor
Fig. 301 Overall Block Diagram
-301-

3-1-2 Outline of stn.ictural parts
This Floppy Disk Drive uses painstakingly assembled high-precision
parts because it uses flexible disks based on mylar film as the record-
ing medium and requires the ability to interchange data with other Flop-
py Disk Drives. For that reason, we request that only specially trained
maintenance personnel be allowed to touch the internal mechanisms and
that the unit be handled carefully, taking care to avoid strong shock.
The components include the frame, door opening and closing mechanism,
disk clamp mechanism, disk drive mechanism, magnetic head and carriage,
head seek mechanism and various detectors.
(1) Frame
The frame is the skeleton on which the various mechanisms and PWB
boards are mounted. It is based on a sheet steel chassis in order to
ensure the strength, accuracy, weather resistance and expansion
ratio required for stable Floppy Disk Drive reliability.
(2) Door opening and closing mechanism, disk clamp mechanism
The door opening and closing mechanism includes the clamp spring
(flat spring), front lever, set arm, etc. The disk clamp mechanism
(clamp assembly) is moved vertically by the end of the clamp spring.
When a disk is inserted and the front lever closed, the end of the
collet enters the central window of the disk, then presses against
the spindle so that the disk is accurately clamped in the correct
position along the collet.
(3) Disk rotating mechanism
The disk rotating system comprises the Disk Drive motor (spindle
motor} including the spindle.
Ihe Disk Drive motor (spindle motor) is a direct spindle coupled
outer rotor type DC brushless motor with an extra long service life
of 20,QCX) hours or more of continuous operation. Ibis servo motor
rotates at 3CX>rpm and maintains a constant speed even with load and
temperature fluctuations using feedback signals from the AC tacho-
meter built into the motor.
The collet and spindle are prec1s1on assembled at exactly the
•
right angle. This prevents injuring the edge of the center window of
the disk and accurately centers the disk so that the head and disk
come into contact at the correct position.
-302-

(4) Magnetic bead and carriage
Read/\Jrite core
Read/\Jrite gap
~ Direction of
disk rotation
Erase core
Tunnel erase type head
Fig. 302 External
Appearance of Magnetic Head Core
With both-side type Floppy Disk Drive units, both the side 0 and
side 1 heads are of a special flat shape supported by a gimbel con-
struction. The beads straddle the disks from the outside and are
mounted on one carriage.
In order to keep wear of the surf aces of the beads from contacting
the disks to a minimum, they are designed to obtain the maximum
playback from the disks. As shown in Fig.302, the heads used in this
Floppy Disk Drive can use tunnel erase type cores.
The center parts of tunnel erase type heads have a Read/Write gap
used to record and playback data and a tunnel erase type gap for
erasing the edges of tracks directly after recording.
(5) Head seek mechanism
The head seek mechanism is built around a stepping motor with a
capstan (pulley) and includes a steel band, guide shaft and car-
riage. The carriage slides along two guide shafts and is connected
to the capstan of the stepping motor via the steel band.
The stepping motor has a flat, 4-phase construction and rotates
one step (l.8° ) to shift the head one track. It is driven by sin-
gle-phase excitation.
The parallelism and distance between the shaft and disk center-
1 ines, as well as the shaft and capstan, are high-precision pro-
cessed. Temperature expansion of the chassis, st~el band, carriage
etc., have been carefully studied and designed to counteract the
expansion of the disk itself.
-303-

(6) Various detectors
(a) File protect detector
This detector comprises the LED and photo transistor used to
detect the presence or absence of the write enable notch on the
disk jacket. When a disk with this notch is loaded, the detec-
tion light path is interrupted and the operation of the write
circuit is prevented. Previously written data is protected from
erasure even if a record command is given by mistake. The LED is
on the Disk Drive motor (spindle motor) servo PWB and the photo
transistor is on the sensor block assembly.
(b) Track 00 detector
This detector comprises a photo interrupter used to detect the
outermost position (track 00) of the head gap and a track 00
stopper.
The tracks inside of track 00 are used but the head cannot
move outside of the range where it can self-reset when the power
is turned on, even if the head should move outside due to a
shock, because it strikes the track 00 stopper. Also designed to
ignore, at the discretion of the circuitry inside the Floppy
Disk Drive, the command to step out from the track 00 position.
In case a step out command is input at the innermost track,
margin is provided so the head does not strike the head window
edge of the disk but, rather, the head moves farther inward. Io
recalibrate (return to track 00) the track from this position,
it is necessary to input a step out conunand for several tracks
beyond the maximum number of tracks.
(c) Index detector
An index bole or center hole detector LED and photo transistor
are located at the position of the index window in the disk
jacket. The LED is on the Disk Drive motor (spindle motor) servo
PWB and the photo transistor is on the sensor block assembly.
The holes in the disk are detected in accordance with the speed
the disk is rotating.
-304-

3-2 Circuit Operation
The circuit section comprises three parts: the Read/Write circuit, the
control circuit and the servo circuit. The Read/Write and control circuit
are on the main PWB' while the servo circuit is on the Disk·Drive motor
(spindle motor) PWB.
3-2-1 Read/Write circuit
The Read/Write circuit comprises the read section, write section and
low voltage detector section. It is mainly in the Read/Write LSI (one-
chip bi-polar LSI). The block diagram is shown in Fig.303.
-305-

I
""
0
en
I
Read/Write coil
Erase coil
Common (center tap)
Diode switch
!._...,._ ___ ....
SIDE~l I ,
-- ;--' I I
' -T---'li
t::::::-_- r=:J
I
I
I
I
Al
Al
WO 0, l
TPl TP2
___ _.Low
pass
filter
AO AO
Write
driver
Data
latch
WO
L ____________ _
2nd
amp
TP4 TP3 TP6 TP7 TPS
r
GND
-----cr-cr--------,
Erase
driver
ED
Peak
Drop
I
RDI
Differ-
ential
amp
detector detector I
Read/Write LSI
Write
power gate
Low
voltage
detection
circuit
LVS
I
I
I
I
I
EG
COM
0, l I
WG SO I
_ _________ ..J
TP8
Fig. 303 Read/Write Circuit Block Diagram
Output
:::ia
~
driver -0
0
~
>

Magnetization of disk
Pre-amp output
Pre-amp output
Differential amp
output
Differential amp
output
-I
1-1-1-1-
-- approx. SV
Fig. 304
TypicQf Read Circuit OperQfing WQveforms
(1) Read section
The read section comprises the pre-amp, low pass filter, differ-
ential amp, peak detector, drop detector and read gate (output
driver).
The micro-voltage conducted to the Read/Write head during playback
is amplified by the pre-amp which consists of a subtraction amplifi-
er, has the spurious noise component removed by the low pass filter
and goes to the differential amp. The differential amp shifts the
playback signal to the zero cross position and simultaneously ap-
plies the proper amE>unt of compensation in accordance with the dif-
ference in the frequency components, and further amplifies it. Ibis
output is converted to a square waveform by the peak detector which
consists of a comparator, the bad influence of the saddle which
occurs during playback of the low-frequency component (IF section:
approx. 125kHz) is eliminated by the drop detector, and is output
from the Floppy Disk Drive via the read gate.
(2) Write section
•
The write section comprises the write power gate, data latch,
write driver, erase driver, and other circuits.
The file protect sensor detects the notch on the side of the disk
-307-

jacket (write enable), the write power gate turns on while the WRITE
GATE input signal is TRUE and the erase gate signal generated by the
timing of the location where the WRITE GATE signal is based is TRUE,
and +12V is applied to the center tap of the. Read/Write head. The
conditions for turning on the power gates are established by the
control circuit.
External WRITE DATA pulse strings are latched by the data latch,
the two line drivers turn on and off alternately to send the proper
record current to the Read/Write head.
Erase heads are positioned by a lattice which straddles a position
0.58mm behind the Read/Write gap. The erase gate signal is delayed
by the amount of 0.7mm offset of WRITE GATE input signal and the
erase driver is operated so it covers the memory area. The delay
timing is controlled by the Write/Erase gate of the control circuit.
Output of the READ DATA pulse is prevented while the write driver
is in the operating mode.
WRITE GATE input signal
(Internal) WRITE GATE
Erase gate signal
SIDE ONE SELECT
WRITE DATA input signal
Data latch output
Write driver output
Write current
Hagnetization of disk
Fig. 305
t-------i- Erase off delay
Erase on delay
o/- /. /'/ % Y. /. :% /. /'.
· Write driver area of operation .__ ___ _
~%,,,)J,/77),,//;'?/// ,!~>;,, /7/7//)///h/,=-,,, ~,,;;L
__ __.r//,-/. Erase driver area of operation////
-,.---·-----...;~-------.--
---'·~~----~~--fl-------~--~
%1-1- l-l-l-l-l-l-l-l-1~2&&
Previous magnetization
Typical Write Circuit Operating Waveforms
-308-

(3) Low voltage detection circuit
The low voltage detection circuit is provided to prevent misopera-
tion occurring in the circuitry in the Floppy Disk Drive while volt-
age is unstable when the power is turned on or off. The output of
this detection circuit is added to almost all of the function blocks
of the Read/Write circuit and control circuit to prevent misopera-
tion of the write driver and erase driver caused when the logic in
the Floppy Disk Drive does not function correctly during the period
of unstable +SV or +12V voltage.
-309-

3-2-2 Control circuit
The control circuit is mainly in the control LSI (one-chip NMOS LSI)
and comprises three major sections: the drive select gate which deter-
mines the drive select conditions, the Write/Erase gate which determines
the timing of the current which flows to the head during recording, the
spindle motor gate which determines the speed of the spindle motor and
other gates, the index detector, track 00 detector, file protect detec-
tor, the ready detection circuit and other detection circuits, and the
stepping motor control circuit.
All detectors (photo transistors) are mounted on the sensor block as-
sembly and track 00 sensor assembly. All other control circuits are
mounted on the main PWB assembly.
The drive select gate comprises the strap (short bar) which transmits
the drive conditions to the control LSI and selects the conditions under
which the front bezel indicator lights.
The Write/Erase gate determines the conditions under which the Floppy
Disk Drive can write and issues the write conunand (write gate or erase
gate signal) to the write circuit. The erase gate signal is given the
required delay time by the internal counter.
The ready detect circuit receives the index pulse from the index de-
tector and outputs the ready signal when the disk reaches the correct
speed.
The stepping motor control circuit comprises the direction latch,
over-drive single shot, etc.
The direction latch samples and holds the direction in which the bead
indicated by the DIRECTION SELECT is moving each time the STEP pulse is
input.
-310-

Read
I
Writ
e
IC
Index detector
File protect
detector
Track (X) detector
Write data
r- Erase
gate
Write gate
Side l select
LSV
Read date
....
Front bezel indicator
Input
signal
Buffer
FDDP
Output
(Floppy Disk Drive Processor) signal
r-
Buffer
'-------- Spindle motor
1----i Over-drive circuit t---+-
Stepping motor ..___
driver
-311-
-
Stepping motor
Interface

The output of the step pulse generator circuit turns on the over-
drive circuit for the prescribed time (approx. 60msec.). During this
time, +12V is impressed on one side of the stepping motor coil so
that sufficient torque is available for seeking and centering. After
centering is completed, sufficient torque is left fo.r holding the
head at the stop position and to prevent unnecessary power loss by
impressing or not impressing +SV on the stepping motor coil. This
also prevents the generation of excessive heat by the motor so power
consumption by the stepping motor when not seeking is only about
0.33W.
DIRECIION SELECI input signal
STEP input signal
Direction latch output
Over-drive circuit input
Hotor driver input
PHASE A
PHASE B
-
PHASE A
-
PHASE B
Step out
Step in
f
u1--+---+--+~~+----+--l----'~
Stops on even
numbered track
Fig. 307 Typical
Stepping Motor Control Circuit Operation Waveforms
-312-

3-2-3 Servo circuit
The servo circuit maintains a constant spindle motor speed and is
.,
mounted on the PWB in the spindle motor unit. The spindle motor (Disk
Drive motor) is.started and stopped by the MOTOR ON signal.from the con-
trol circuit.
This is an alternating current type, long life brushless 3-phase coil
motor driven by a special 3-phase driver IC. The 3-phase flow of elec-
tricity and the switching of the direction of excitation are performed
by signals from the Hall element mounted on the PWB on the outer pe-
riphery of the rotor, with the sequential drive coil and direction of
extation controlled so they switch to the prescribed direction of
rotation. The speed of rotation is accurately maintained at the desired
valve by F-V converting (frequency to vqltage conversion) the feedback
signal from the AC tachometer etched on the PWB inside the rotor with
another servo IC and applying this to the drive voltage control section
of the 3-phase driver IC.
-313-

3-3·Test Point Functions and Type of Connectors
Fig.308 shows the layout of the test points and connectors.
Main PWB assembly label
Drawing no.
Issue (A,B,C ···)
Type of connectors
Jl: Interface connectors
J2: Power supply connector
J3: Track 00 connector
JJ
J4: Disk Drive motor (spindle motor}
connector
JS: Stepping motor connector
J6: Sensor block connector
J7: Head connector
Test point functions
IPl: Pre-amp out
IP2: Pre-amp
out
TP3:
2nd amp out
IP4: 2nd
amp out
TPS: GND (OV}
IP6:
Differential amp
IP7:
Differential amp
IP8: Erase gate
TP9: Track 00 sensor
-314-
r----,
I '
L----'
J4
Fig.308
J1
JS
Layout of Test Points
and Connectors

3-3-1 Test point functions
The following 9 test points (including one ground) are provided for
monitoring the waveforms required for inspection and adjustment of the
Floppy Disk Drive on main PWB assembly.
(1) TP9 {track 00 sensor)
This test point is provided for monitoring the output of the photo
transistor (Schmidt inverter built-in) used for track 00 detection.
Like the TRACK 00 output signal, the state is LOW when the head is
on or near track 00.
Track 00 sensor
Track 02 ~
-------(TTL level)
~Track 00
Fig. 309 Typical Waveform
Note: 1. The TRACK 00 output signal first becomes TRUE (WW level)
while the basic excitation Phase A for the stepping motor is
excited. Because of this, the timing of the TP9 waveform
variation is not constant.
(2) TP8 (erase gate)
This test point is for monitoring the erase gate signal. At the
LOW level, the prescribed current is flowing in the erase head.
This is used to check the erase gate delay time against the WRITE
GATE input signal.
WRITE GATE input signal
-,.__ ______ I
Erase gate 1 d
On delay 1]1----0ff-de-la-y -+- _- _- _---1. J
Fig. 310 Typical Waveforms