MPI 40 Series - Page 78

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4.6.1

Radial-Track Alignment

To

perform

the

radial-track

alignment

proceed

as

follows:

A. Loosen

the

end-stop

screw

on

the

bottom

of

drive.

B. Apply power

to

the

disk

drive.

Apply

controls

to

the

drive

for

recalibration

to

track

00.

C.

Insert

a

CE

alignment

diskette

(MPI

Part

No.

78901-428

double/single)

and

close

the

door.

D.

Sync

oscilloscope

on

leading

edge

of

signal

on

TP

8

(output

of

U30-11, on

Control

Electronics

schematics).

Connect

oscilloscope

probes

to

TP4

and

TPS

(inputs

to

US-1,

14).

Set

the

oscilloscope

to

lOOmV/cm,

ac

coupled,

channel

A and

B

added,

with

B

inverted,

20ms/division.

Attach

ground

probe

to

minus

side

of

CS.

E.

Load

head

and

apply

38

stepping

pulses,

with

the

DIRECTION

line

low.

The

carriage

should

now

be

located

around

track

38.

The

proper

phase

relationship

of

stepper

motor

phases

should

be:

phase

4

and

1 =

OV,

phase

2

and

3 =

+24V.

F.

With power on

loosen

the

stepper

motor

mounting

screws

on

bottom

of

drive

and

rotate

the

motor

so

that

the

"cat's

eye"

pattern

appears

on

the

scope

and

adjacent

lobes

are

within

70%

amplitude.

However,

ideal

alignment

is

indicated

when

adjacent

lobes

have

equal

amplitude.

Tighten

mounting

screws.

Command

a

return

to

track

00 and

then

step

back

to

track

38

to

verify

proper

alignment.

Command

a

seek

to

track

76

and

then

step

back

to

track

38

to

verify

proper

alignment.

G.

Perform

the

Track

00 End

Stop

adjustment,

paragraph

4.6.S.

4.6.2 Index-To-Data Alignment

To

perform

the

index-to-data

alignment

perform

the

following

steps

in

the

order

listed:

A.

Verify

the

radial-track

alignment

(see

-paragraph

4.6.1)

then

move

the

head

to

track

73.

B.

Set

the

oscilloscope

to

200mV/cm;

SO~s/division.

c. The

index

sensor

mounting

screw

is

located

at

the

bottom

of

the

drive

in

the

recessed

area.

Loosen

the

screw

and

slide

the

sensor

such

that

the

oscilloscope

picture

shows a

data

pattern

starting

200 +100

microseconµs

from

the

start

of

the

trace

while

keeping

the

sensor

assembly

pressed

firmly

against

the

sensor

assembly

alignment

rail

(refer

to

figure

4-2).

MPI

recommends

that

the

alignment

should

be

performed

as

close

to

200usec

as

possible.

D.

Using

a 20

inch-ounce

torque

screwdriver,

tighten

the

screws

carefully

so

that

no

variations

in

the

oscilloscope

display

occur.

4-25

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