DECtapeSkewAdj pdf

(1)

(

· i

..

~!'ll:". 'I£-.._:..,...~'111~ .• ~.---.: ~111'::.~~~ ItLS2 "-'--~tn...--~·~~~~~= ____ ~"'~IlI!IIr;"""",,,_oe.~

p[flr~~S/

FAMILY DECTAPE

FIELD SERVICE TECH MANUAL

ADJUSTMENTS FOR DECTAPE ~YSTEMS (Continued)

TO USE: (1 )

(2)

Plug in skew tester AFTER selecting source of V plus, see

NOTES on S3 and TO USE: (5), 53.

Calibrate. See NOTES on 51 and TO USE: (5),53.

(~) Select correct split winding, see NOTES on S2 and TO USE:

(5), S2.

(4) Skew Test

A. Zero Skew Tape Available: (Certified DECtapes are not

zero skew. They may· have a l~ sec skew.) Run tape

across head in normal manner. Gain of tester is enough

to give clipped sine wave out. About 10V PIP. Go to

step 4C. This skew is real.

B. No Zero Skew Tape Available. Clean tape head and guides.

(4~E) Format Tape. Reverse tape so oxide side is up. (4-F) Now thread this tape from take-up reel across head

with oxide up onto original supply reel. Move tape in

local mode. Go to step 4C. The skew indicated is twice

real skew.

C. Skew is measured by measuring the time difference between

the two signals crossing a given reference line. Figure

1. To test skew; with tape in motion, depress lightly on

the back edge of the tape on the right or left sides of

the head. Record whirih side causes the skew to increase

when pressure is applied to 'one side or the other. If

D.

the real skew is greater than 2/-4... sec, the head should be

deskewed. This tolerance will apply to both TU5S and Tu56

transports to gain an added factor of interchangeability

of tapes. I f the head is to be deskewed, i t should be taken

as close to zero as possible. If a non-zero skew is used,'

i t must be formatted after each attempt to deskew.

To deskew:

1. Remove head and thoroughly clean back of head and

mounting surface of ail dirt, glue, skew shims, etc~·

Remount head and redo 4A or 4B as applicable.

2. I f shimming is necessary, magtape reflective marker

(DEC #29-15191) is acceptable. Place the marker on

~.

the back of the head on the edge of the side which

caused the skew to increase in step 4C. (For TU56.

heads, the reflective tape must be placed only below

the mounting screw.) Remount head being careful not to

(2)

~ .... ,"r,,~~-_::'"""l2J_~,-..:;,r=-a~~~_"Z!mI_osm:laIIe-:l" _ _ zmm_~ ... __

-nt='r-. I ' I

I

PDP..",S/S

DECTAPE

(

FIELD SERVICE TECH MANUAL.

ADJUSTMENTS FOR DECTAPE SYSTEMS (Continued)

TO USE: (4) Skew Test (Continued)

E. To Clean:

1. Heads and Guides: Use DECtape cleaning solution

generously on the head, wiping dirt wi tho clean,

lint free towel (Kimwipe).

2. Guides: Disassemble guide from plate and

thor-oughly clean with solution all parts including wear plates, studs, springs, spring holes and guides themselves.

3. Tape: Place doubled clean, lint free towel over

head; thread tape over tow~l; place free end of

towel over tape.

Run tape from end-tp-end at least once in each

direction.

F. Reversing Tape: (Oxide side up)

Figure 4-F-1

Mount normally full reel of tape on right hub and empty

reel on left. Thread tape from bottom of full spool onto

top of empty reel. In local move all tape to left reel.

This places oxide side up for skew test.

CAUTION: Maintain manual pressure on the supplying

reel to prevent tape runaway.

(5) Switches: NC

=

DOWN NO = UP

Sl (Middle Switch) Calibrate - NO/Normal - NC

NO Select signal to lower amp to compensate for internal

drift and phase shift of op amps. To calibrate, put

switch in NO position, scope in Add, tape oxide side

up and move tape in local. The two signals are 1800

phase and should cancel. ADJ 10KPOT for smallest

resultant signal. Return switch to NC position.

NC Signal from other half split winding is applied to

lower amp for skew test. Do not adjust pot for any

difference in amplitude. This difference is a result

of low signal from one half of split winding due to sket-l.

~

9 OF

16f1

~AGE

REVISION 0 [[pUBLICATION

DI~TE

February: 15, 197: )

[image:2.615.34.591.23.780.2]

(3)

TO USE:

TU55/56

(5) Switches (continued)

S2 Top Switch: Select split wi~ding, due to different vendors assigning different pins for head connection. I f switch is in wrong position, SlG2 will be twice amplitude of SlG1 in normal position of Sl, when oxide side up. I f oxide sid~ is down, a phase shift plus skew will result.

S3 Bottom Switch: For compatibility to R series transports NC-- +5V i f applied to V plus.

NO-- +10V is divided to +5 for V plus.

CAUTION: This selection is to be made before voltages are applied.

Skew Tester may be placed in any empty slot which has +5 (or +10), -15, and ground in pins A2, B2 and C2 respectively.

Attach female data cable from head to male of tester.

PARTS LIST:

NOTES:

MC1709CG

220 011M 1/4W 5% 4.7K 1/4W 5% 1.5K 1/4rl 5% 22K 1/4W 5% 10K POT

470K 1/4W 5% ·330 OHM 1/2W 5%

1N753A

22pf 100V 5% 10pf 100V 5% .01mf 100V 5% 6.8 mf 35V 20% 1 PST 6 AT1-T2 Ampheno1

19-9344 - E1 through E4

13-0271 13-0447 13-0391 13-1808 13-9143-10

13-2398

13-0296

11-2421

10-0021 10-0006 10-1610 10-0067

12-1168

133-022-03 12-2909

680 OHM 1/2W 5% 13-0347 1. Ampheno1 Pin Assignments

-pin A Skew Tap. -Pin D Center Tap.

-pin B solid winding on Western Magnetic head. Split winding on Brush head.

-pin C Split winding on Western Magnetic or General Instrument. Solid winding on Brush.

Split winding for skew measurement.

~100~~

PAGE HEVISION .

~

lJ

PU3L1C/\TION DATE February 15,

~9i}

(4)

(

,

DECTAPES

FIELD SERVICE TECH MANUAL

tliC!025i.UCW ili&C za ESi!Sl!d(,'M"

Notes: (continued)

2. M series use NC position of 83 (+5 applied to A2).

R series use NO position of S3 (+10 V applied to A).

j. i El-E4 MCl709 CG. Pin 4 = V minus 'Pin 7

=

V plus.

unless otherwise noted resistors are in OHM, l/4W. 5%

4. MC1709 CG.

Pin side.

1

E-5. Sl = calibrate/normal

S2 = select split wina~ng

(5)

o

i5

~

rjg

G>

mfTl

~~

!-.o

"'~

"

]l~

~;-.

in

Z

-.~i _I]>tJ

Q

0

111

0"

_r.:~_tTl _tJ

<

'TIiU>

0,'0

~

z

YI

4 f

-tiC)

o

ZI"U

a

c:

91 ~.~

,,>

v~

-(0

ZjZ

P

IO

:ol~

nrri

~I

_'"ll

~I~

»Ici

ff)IPJ

~F.

₀

_:

_"""'

-f'"

.L

r-Lr-a

Ull\tl

m

-i ~

(f)

"--"

f

---

_

...

1"--"""

;

,

~~ANNeL

'

1 '

-...

C~-ANNE~ ...

"Z.

~

"

FIGURE 1

Input Coupllng: AC; Sync: AC HF REJ; ADJ,both

eH

to , level

Sync on channell. Put start of sweep at left ~nd of X axis.

Position seep 2 to start at same point. The difference in time where

the two sweep across the X axis is the skew.

NOTE: Signals shown are for reference only to show skew measurement.

They may be square wave (step 4A) or negative portion of this

signal depending on tape direction (step 4B).

r---"

"

-

_m

r

o

en

m

~

fjlJl

mD

_~

I::nl

-I

~

"m,

,

.

~

O[Q@

I

~

»

z

c

[image:5.793.10.773.23.581.2]

»

_r

...

'"ll

~

I--t

~ ~

~

t:J ~ ~ ~

~

t:J

,

!

I

(6)

J

-:l

.!~

~

>1""0

->

~l~

l:!f-...

'.I I....J

-10

--!-,

,

":,>l"~,,,' r-:.l

,-1.'1

~p,~O)

111

~'~

J~

{!"

"I

rn,'1

1,'::;

') (l,)

jl§ll

] I

;10

p

~G

:Q

.I~I

_1(>

I.>

Il~ 'j(5

;Iz

:p~

'!-f

;!!"i1!

~ I

.~

-r,

:'Ij

~~

-..

~

) 1...: _C'i',. "'n

"to "'J '\ ..

)b

~

C}

»

1

!N

~ ~

,. \ I'

~~I~ ~

,§J

-I

Q

I i

\

r--.

i

L

O'l.loe 5 IDt: v( P

~ ~ 00 0 U T P fA TAg 0 I.(

r

~" p / ?

/~-...

(

~-

SKt5W

I

b~/Dt£ $I/)~

j}oWI'I

. l?

~

() ()

C tl "( f? tI 7 ,4 8 (HI T 10 V f / P.

These pictures are for reference only; however can be used to illuatrate a point.

Given: Tape: Moving Forward

Channel 2 leads channell as shown.

If tape is reversed, channel 2 should lag channell, as shown with dotted lines, the same amount as i t leads going forward. If this condition is ~ot met, either amount is different or does not swap

from lead to lag~ It indicates faulty guides ~hich must be cleaned

or replaced.

.----'\

"

-

_m

l

r

o

m

~

O

-~

_','U

_~s

~

m

D

~

rri

11 ~

O

m

",~"f;i" J-:.'1.

.:'-:.'~

T

"-...c.... ~

~

l>

Z

C

l>

r

~

/:'i

~

t::1

ttj (')

~3

~I '\J

ttl

i

(7)

·

0

(j)

-i

»1"'0

rl>

G>

mlrn

~'

,,

'

[I~

- i ' l

1]1---0

7~ ~

m ;

Z

-11;g

G)

Olm

Q::r.J

(T1

IJ<

M

-tJ ~

Dig

"'0 .:;.

,/-

-1>

-;

',

\0

o

Z~

NORMAL

o

~

.

E Nt PT'I

~ ~

REf:l

l>~

-<

-I

Z,~

)> ~~

JJ

-l -"

O·fTl

_I

D'-~~

i

»~

m

m~

I

.t:.

m

.

E ..

VJ~ 'l1

»1

~F

cL

(J)~

~tJ

_-i

en

Link Tape:

Q

TAPE FLOW

TU55/56

Reverse Tape

NORMAL

FtALL

RE"EL

Put normal full reel on left hub, empty on right

hub. Thread from bottom of left to top of right.

In local wind all tape onto right reel.

r

. . -... "\

"

-

_m

r

o

m

1 ~

,..,

~ , ,,

-m

~

_~~

-

,

'

,

:

'

i

~'

.

'

,

~

-1

~

"

m

.

~

"

~ ~

l J ~. "

I

~

»

z

c

»

_r

"

~ ~

::::

\-.f

f:-i

~

I

~

I

c '

• tl I?

~ '

() .

~

.

~ ~

'

~

i

(8)

~ I~-'.:lir.ok _ _ _ """"""a.::r'_""

.'£"'<'"!"---

_~~~'~.c,3lI!III!:':iI _ _ ~~"""""'~--""""-~=...,.C&Zt~!b"

( I

C

-::r

t

("'(

\I') \.E _(\... ...t

<to _\(\

':;j _\on

<-

:S'

ct. 1-£

(..\.

\u

c:a::.

\ ,_

.. /

~[O~~~

/FAMILY

FIELD

SERVICE TECH MANUAL

~

\U

~

V\

\U

\-o

~

~\lJ

w~

\I)

Q

<t

\lJ

::r:

r-\ \1\ \!)"

(L

- t \J'\

:s

I-DECTAPE

?! 0.1-;J iJ /'./ A' 0 ;;J

.;:?7t:/W;J.:l

(9)

o

G1

-i

PI

'"0

r~

ml~

~~O\

---n

VI-/ 0 \

~

m

I

LI-o

--1Ii>

Q

Om

O~

1J<

lJ~

0

~Zl

• t f

-1. c

o

Z

IJ

f;\

C

a

w v,.

7' C

0 ~ ~i

<)

v ·

~~

_ZG;.

p~ JJ~

Om

'"ll CD

~ ~

l>

~

ill ~

(DtC

»

l

-n

_~ ~"l

...

I

CI-(J)~

m

r-v -I

-i

en

V\

"

m

~'

-\

tn C/\

-l

rn

;Q

,,"'.'.

~

~ 1"\

~ <:)

~ \

-:t:~

g. <:)

. - ' ~t'l"')

<~

~o

No

N~

,~

r-l~

I~o-l

"

J,.

C.

!~r>.

~

U

v-I-L

NO:uP $1..

_ fOP ~~ er(. (-oJ

q

I

51

f!No:t..tP

M\DOLC

swlTC. H

,

1

1..'20

'Z.Zo

1..2D

, 2 0

~,

22K

vpt..rJS

V f{\INU, S

"lZK

" PLU"

2.U>Q'!>

f'+ K

~Ul

f----::

f lJ.

~

I

.Of/,,-t 10 rf

:l

V MINUS

PJrI~2.

-L

3~"O

"til/NUS

?ltll:l2

"v

I I

~7

IN7S3A

PIIJA2

LJ7

0K

V Pz..u..,5

I

V MINUS

Ll1°1{

V PJ.

u.s

_-~-CIZ

t./.7K

I

1 t-1"5

l/ " MINc/'~

5)~

<.

61..\.(£

Sl6 J

RfO

V PLIAS

we.

~

c. S "3

" tV 0 :: ./.L P

-'sv

~1Fft·

II'

+5"

o R

-flo

v

I

• 0

~-r

I

j) "80

"""0

M I

r 5wtT£.tI

• 0 p~

----.

,

----

'

1 "

-

_m

r

o

,

i

_~

~

I

ffi

i

~

!

fj

~

i

g

m

,

(J~'

"

.

'

".

}:!"

I

-'~

-.

~

m~.

I

(1

~¥'!,', "~:;) ~, ill ,

~,i

11

I

~

, ~ ~

~S

~

c

»

r

o

m

:i"tl 't;lj i/. ~